Add m-esr52 at 52.6.0

1 files changed, 3368 insertions, 0 deletions

diff --git a/media/libvpx/vp8/encoder/firstpass.c b/media/libvpx/vp8/encoder/firstpass.c
new file mode 100644
index 000000000..3deb4abb3
--- /dev/null
+++ b/media/libvpx/vp8/encoder/firstpass.c
@@ -0,0 +1,3368 @@
+/*
+ *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <math.h>
+#include <limits.h>
+#include <stdio.h>
+
+#include "./vpx_dsp_rtcd.h"
+#include "./vpx_scale_rtcd.h"
+#include "block.h"
+#include "onyx_int.h"
+#include "vp8/common/variance.h"
+#include "encodeintra.h"
+#include "vp8/common/setupintrarecon.h"
+#include "vp8/common/systemdependent.h"
+#include "mcomp.h"
+#include "firstpass.h"
+#include "vpx_scale/vpx_scale.h"
+#include "encodemb.h"
+#include "vp8/common/extend.h"
+#include "vpx_mem/vpx_mem.h"
+#include "vp8/common/swapyv12buffer.h"
+#include "rdopt.h"
+#include "vp8/common/quant_common.h"
+#include "encodemv.h"
+#include "encodeframe.h"
+
+/* #define OUTPUT_FPF 1 */
+
+extern void vp8cx_frame_init_quantizer(VP8_COMP *cpi);
+
+#define GFQ_ADJUSTMENT vp8_gf_boost_qadjustment[Q]
+extern int vp8_kf_boost_qadjustment[QINDEX_RANGE];
+
+extern const int vp8_gf_boost_qadjustment[QINDEX_RANGE];
+
+#define IIFACTOR   1.5
+#define IIKFACTOR1 1.40
+#define IIKFACTOR2 1.5
+#define RMAX       14.0
+#define GF_RMAX    48.0
+
+#define KF_MB_INTRA_MIN 300
+#define GF_MB_INTRA_MIN 200
+
+#define DOUBLE_DIVIDE_CHECK(X) ((X)<0?(X)-.000001:(X)+.000001)
+
+#define POW1 (double)cpi->oxcf.two_pass_vbrbias/100.0
+#define POW2 (double)cpi->oxcf.two_pass_vbrbias/100.0
+
+#define NEW_BOOST 1
+
+static int vscale_lookup[7] = {0, 1, 1, 2, 2, 3, 3};
+static int hscale_lookup[7] = {0, 0, 1, 1, 2, 2, 3};
+
+
+static const int cq_level[QINDEX_RANGE] =
+{
+    0,0,1,1,2,3,3,4,4,5,6,6,7,8,8,9,
+    9,10,11,11,12,13,13,14,15,15,16,17,17,18,19,20,
+    20,21,22,22,23,24,24,25,26,27,27,28,29,30,30,31,
+    32,33,33,34,35,36,36,37,38,39,39,40,41,42,42,43,
+    44,45,46,46,47,48,49,50,50,51,52,53,54,55,55,56,
+    57,58,59,60,60,61,62,63,64,65,66,67,67,68,69,70,
+    71,72,73,74,75,75,76,77,78,79,80,81,82,83,84,85,
+    86,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100
+};
+
+static void find_next_key_frame(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame);
+
+/* Resets the first pass file to the given position using a relative seek
+ * from the current position
+ */
+static void reset_fpf_position(VP8_COMP *cpi, FIRSTPASS_STATS *Position)
+{
+    cpi->twopass.stats_in = Position;
+}
+
+static int lookup_next_frame_stats(VP8_COMP *cpi, FIRSTPASS_STATS *next_frame)
+{
+    if (cpi->twopass.stats_in >= cpi->twopass.stats_in_end)
+        return EOF;
+
+    *next_frame = *cpi->twopass.stats_in;
+    return 1;
+}
+
+/* Read frame stats at an offset from the current position */
+static int read_frame_stats( VP8_COMP *cpi,
+                             FIRSTPASS_STATS *frame_stats,
+                             int offset )
+{
+    FIRSTPASS_STATS * fps_ptr = cpi->twopass.stats_in;
+
+    /* Check legality of offset */
+    if ( offset >= 0 )
+    {
+        if ( &fps_ptr[offset] >= cpi->twopass.stats_in_end )
+             return EOF;
+    }
+    else if ( offset < 0 )
+    {
+        if ( &fps_ptr[offset] < cpi->twopass.stats_in_start )
+             return EOF;
+    }
+
+    *frame_stats = fps_ptr[offset];
+    return 1;
+}
+
+static int input_stats(VP8_COMP *cpi, FIRSTPASS_STATS *fps)
+{
+    if (cpi->twopass.stats_in >= cpi->twopass.stats_in_end)
+        return EOF;
+
+    *fps = *cpi->twopass.stats_in;
+    cpi->twopass.stats_in =
+         (void*)((char *)cpi->twopass.stats_in + sizeof(FIRSTPASS_STATS));
+    return 1;
+}
+
+static void output_stats(const VP8_COMP            *cpi,
+                         struct vpx_codec_pkt_list *pktlist,
+                         FIRSTPASS_STATS            *stats)
+{
+    struct vpx_codec_cx_pkt pkt;
+    (void)cpi;
+    pkt.kind = VPX_CODEC_STATS_PKT;
+    pkt.data.twopass_stats.buf = stats;
+    pkt.data.twopass_stats.sz = sizeof(FIRSTPASS_STATS);
+    vpx_codec_pkt_list_add(pktlist, &pkt);
+
+/* TEMP debug code */
+#if OUTPUT_FPF
+
+    {
+        FILE *fpfile;
+        fpfile = fopen("firstpass.stt", "a");
+
+        fprintf(fpfile, "%12.0f %12.0f %12.0f %12.4f %12.4f %12.4f %12.4f"
+                " %12.4f %12.4f %12.4f %12.4f %12.4f %12.4f %12.4f %12.4f"
+                " %12.0f %12.0f %12.4f\n",
+                stats->frame,
+                stats->intra_error,
+                stats->coded_error,
+                stats->ssim_weighted_pred_err,
+                stats->pcnt_inter,
+                stats->pcnt_motion,
+                stats->pcnt_second_ref,
+                stats->pcnt_neutral,
+                stats->MVr,
+                stats->mvr_abs,
+                stats->MVc,
+                stats->mvc_abs,
+                stats->MVrv,
+                stats->MVcv,
+                stats->mv_in_out_count,
+                stats->new_mv_count,
+                stats->count,
+                stats->duration);
+        fclose(fpfile);
+    }
+#endif
+}
+
+static void zero_stats(FIRSTPASS_STATS *section)
+{
+    section->frame      = 0.0;
+    section->intra_error = 0.0;
+    section->coded_error = 0.0;
+    section->ssim_weighted_pred_err = 0.0;
+    section->pcnt_inter  = 0.0;
+    section->pcnt_motion  = 0.0;
+    section->pcnt_second_ref = 0.0;
+    section->pcnt_neutral = 0.0;
+    section->MVr        = 0.0;
+    section->mvr_abs     = 0.0;
+    section->MVc        = 0.0;
+    section->mvc_abs     = 0.0;
+    section->MVrv       = 0.0;
+    section->MVcv       = 0.0;
+    section->mv_in_out_count  = 0.0;
+    section->new_mv_count = 0.0;
+    section->count      = 0.0;
+    section->duration   = 1.0;
+}
+
+static void accumulate_stats(FIRSTPASS_STATS *section, FIRSTPASS_STATS *frame)
+{
+    section->frame += frame->frame;
+    section->intra_error += frame->intra_error;
+    section->coded_error += frame->coded_error;
+    section->ssim_weighted_pred_err += frame->ssim_weighted_pred_err;
+    section->pcnt_inter  += frame->pcnt_inter;
+    section->pcnt_motion += frame->pcnt_motion;
+    section->pcnt_second_ref += frame->pcnt_second_ref;
+    section->pcnt_neutral += frame->pcnt_neutral;
+    section->MVr        += frame->MVr;
+    section->mvr_abs     += frame->mvr_abs;
+    section->MVc        += frame->MVc;
+    section->mvc_abs     += frame->mvc_abs;
+    section->MVrv       += frame->MVrv;
+    section->MVcv       += frame->MVcv;
+    section->mv_in_out_count  += frame->mv_in_out_count;
+    section->new_mv_count += frame->new_mv_count;
+    section->count      += frame->count;
+    section->duration   += frame->duration;
+}
+
+static void subtract_stats(FIRSTPASS_STATS *section, FIRSTPASS_STATS *frame)
+{
+    section->frame -= frame->frame;
+    section->intra_error -= frame->intra_error;
+    section->coded_error -= frame->coded_error;
+    section->ssim_weighted_pred_err -= frame->ssim_weighted_pred_err;
+    section->pcnt_inter  -= frame->pcnt_inter;
+    section->pcnt_motion -= frame->pcnt_motion;
+    section->pcnt_second_ref -= frame->pcnt_second_ref;
+    section->pcnt_neutral -= frame->pcnt_neutral;
+    section->MVr        -= frame->MVr;
+    section->mvr_abs     -= frame->mvr_abs;
+    section->MVc        -= frame->MVc;
+    section->mvc_abs     -= frame->mvc_abs;
+    section->MVrv       -= frame->MVrv;
+    section->MVcv       -= frame->MVcv;
+    section->mv_in_out_count  -= frame->mv_in_out_count;
+    section->new_mv_count -= frame->new_mv_count;
+    section->count      -= frame->count;
+    section->duration   -= frame->duration;
+}
+
+static void avg_stats(FIRSTPASS_STATS *section)
+{
+    if (section->count < 1.0)
+        return;
+
+    section->intra_error /= section->count;
+    section->coded_error /= section->count;
+    section->ssim_weighted_pred_err /= section->count;
+    section->pcnt_inter  /= section->count;
+    section->pcnt_second_ref /= section->count;
+    section->pcnt_neutral /= section->count;
+    section->pcnt_motion /= section->count;
+    section->MVr        /= section->count;
+    section->mvr_abs     /= section->count;
+    section->MVc        /= section->count;
+    section->mvc_abs     /= section->count;
+    section->MVrv       /= section->count;
+    section->MVcv       /= section->count;
+    section->mv_in_out_count   /= section->count;
+    section->duration   /= section->count;
+}
+
+/* Calculate a modified Error used in distributing bits between easier
+ * and harder frames
+ */
+static double calculate_modified_err(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
+{
+    double av_err = ( cpi->twopass.total_stats.ssim_weighted_pred_err /
+                      cpi->twopass.total_stats.count );
+    double this_err = this_frame->ssim_weighted_pred_err;
+    double modified_err;
+
+    if (this_err > av_err)
+        modified_err = av_err * pow((this_err / DOUBLE_DIVIDE_CHECK(av_err)), POW1);
+    else
+        modified_err = av_err * pow((this_err / DOUBLE_DIVIDE_CHECK(av_err)), POW2);
+
+    return modified_err;
+}
+
+static const double weight_table[256] = {
+0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
+0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
+0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
+0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000, 0.020000,
+0.020000, 0.031250, 0.062500, 0.093750, 0.125000, 0.156250, 0.187500, 0.218750,
+0.250000, 0.281250, 0.312500, 0.343750, 0.375000, 0.406250, 0.437500, 0.468750,
+0.500000, 0.531250, 0.562500, 0.593750, 0.625000, 0.656250, 0.687500, 0.718750,
+0.750000, 0.781250, 0.812500, 0.843750, 0.875000, 0.906250, 0.937500, 0.968750,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
+1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000
+};
+
+static double simple_weight(YV12_BUFFER_CONFIG *source)
+{
+    int i, j;
+
+    unsigned char *src = source->y_buffer;
+    double sum_weights = 0.0;
+
+    /* Loop throught the Y plane raw examining levels and creating a weight
+     * for the image
+     */
+    i = source->y_height;
+    do
+    {
+        j = source->y_width;
+        do
+        {
+            sum_weights += weight_table[ *src];
+            src++;
+        }while(--j);
+        src -= source->y_width;
+        src += source->y_stride;
+    }while(--i);
+
+    sum_weights /= (source->y_height * source->y_width);
+
+    return sum_weights;
+}
+
+
+/* This function returns the current per frame maximum bitrate target */
+static int frame_max_bits(VP8_COMP *cpi)
+{
+    /* Max allocation for a single frame based on the max section guidelines
+     * passed in and how many bits are left
+     */
+    int max_bits;
+
+    /* For CBR we need to also consider buffer fullness.
+     * If we are running below the optimal level then we need to gradually
+     * tighten up on max_bits.
+     */
+    if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+    {
+        double buffer_fullness_ratio = (double)cpi->buffer_level / DOUBLE_DIVIDE_CHECK((double)cpi->oxcf.optimal_buffer_level);
+
+        /* For CBR base this on the target average bits per frame plus the
+         * maximum sedction rate passed in by the user
+         */
+        max_bits = (int)(cpi->av_per_frame_bandwidth * ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
+
+        /* If our buffer is below the optimum level */
+        if (buffer_fullness_ratio < 1.0)
+        {
+            /* The lower of max_bits / 4 or cpi->av_per_frame_bandwidth / 4. */
+            int min_max_bits = ((cpi->av_per_frame_bandwidth >> 2) < (max_bits >> 2)) ? cpi->av_per_frame_bandwidth >> 2 : max_bits >> 2;
+
+            max_bits = (int)(max_bits * buffer_fullness_ratio);
+
+            /* Lowest value we will set ... which should allow the buffer to
+             * refill.
+             */
+            if (max_bits < min_max_bits)
+                max_bits = min_max_bits;
+        }
+    }
+    /* VBR */
+    else
+    {
+        /* For VBR base this on the bits and frames left plus the
+         * two_pass_vbrmax_section rate passed in by the user
+         */
+        max_bits = (int)(((double)cpi->twopass.bits_left / (cpi->twopass.total_stats.count - (double)cpi->common.current_video_frame)) * ((double)cpi->oxcf.two_pass_vbrmax_section / 100.0));
+    }
+
+    /* Trap case where we are out of bits */
+    if (max_bits < 0)
+        max_bits = 0;
+
+    return max_bits;
+}
+
+void vp8_init_first_pass(VP8_COMP *cpi)
+{
+    zero_stats(&cpi->twopass.total_stats);
+}
+
+void vp8_end_first_pass(VP8_COMP *cpi)
+{
+    output_stats(cpi, cpi->output_pkt_list, &cpi->twopass.total_stats);
+}
+
+static void zz_motion_search( VP8_COMP *cpi, MACROBLOCK * x,
+                              YV12_BUFFER_CONFIG * raw_buffer,
+                              int * raw_motion_err,
+                              YV12_BUFFER_CONFIG * recon_buffer,
+                              int * best_motion_err, int recon_yoffset)
+{
+    MACROBLOCKD * const xd = & x->e_mbd;
+    BLOCK *b = &x->block[0];
+    BLOCKD *d = &x->e_mbd.block[0];
+
+    unsigned char *src_ptr = (*(b->base_src) + b->src);
+    int src_stride = b->src_stride;
+    unsigned char *raw_ptr;
+    int raw_stride = raw_buffer->y_stride;
+    unsigned char *ref_ptr;
+    int ref_stride = x->e_mbd.pre.y_stride;
+    (void)cpi;
+
+    /* Set up pointers for this macro block raw buffer */
+    raw_ptr = (unsigned char *)(raw_buffer->y_buffer + recon_yoffset
+                                + d->offset);
+    vpx_mse16x16(src_ptr, src_stride, raw_ptr, raw_stride,
+                 (unsigned int *)(raw_motion_err));
+
+    /* Set up pointers for this macro block recon buffer */
+    xd->pre.y_buffer = recon_buffer->y_buffer + recon_yoffset;
+    ref_ptr = (unsigned char *)(xd->pre.y_buffer + d->offset );
+    vpx_mse16x16(src_ptr, src_stride, ref_ptr, ref_stride,
+                 (unsigned int *)(best_motion_err));
+}
+
+static void first_pass_motion_search(VP8_COMP *cpi, MACROBLOCK *x,
+                                     int_mv *ref_mv, MV *best_mv,
+                                     YV12_BUFFER_CONFIG *recon_buffer,
+                                     int *best_motion_err, int recon_yoffset )
+{
+    MACROBLOCKD *const xd = & x->e_mbd;
+    BLOCK *b = &x->block[0];
+    BLOCKD *d = &x->e_mbd.block[0];
+    int num00;
+
+    int_mv tmp_mv;
+    int_mv ref_mv_full;
+
+    int tmp_err;
+    int step_param = 3; /* Dont search over full range for first pass */
+    int further_steps = (MAX_MVSEARCH_STEPS - 1) - step_param;
+    int n;
+    vp8_variance_fn_ptr_t v_fn_ptr = cpi->fn_ptr[BLOCK_16X16];
+    int new_mv_mode_penalty = 256;
+
+    /* override the default variance function to use MSE */
+    v_fn_ptr.vf    = vpx_mse16x16;
+
+    /* Set up pointers for this macro block recon buffer */
+    xd->pre.y_buffer = recon_buffer->y_buffer + recon_yoffset;
+
+    /* Initial step/diamond search centred on best mv */
+    tmp_mv.as_int = 0;
+    ref_mv_full.as_mv.col = ref_mv->as_mv.col>>3;
+    ref_mv_full.as_mv.row = ref_mv->as_mv.row>>3;
+    tmp_err = cpi->diamond_search_sad(x, b, d, &ref_mv_full, &tmp_mv, step_param,
+                                      x->sadperbit16, &num00, &v_fn_ptr,
+                                      x->mvcost, ref_mv);
+    if ( tmp_err < INT_MAX-new_mv_mode_penalty )
+        tmp_err += new_mv_mode_penalty;
+
+    if (tmp_err < *best_motion_err)
+    {
+        *best_motion_err = tmp_err;
+        best_mv->row = tmp_mv.as_mv.row;
+        best_mv->col = tmp_mv.as_mv.col;
+    }
+
+    /* Further step/diamond searches as necessary */
+    n = num00;
+    num00 = 0;
+
+    while (n < further_steps)
+    {
+        n++;
+
+        if (num00)
+            num00--;
+        else
+        {
+            tmp_err = cpi->diamond_search_sad(x, b, d, &ref_mv_full, &tmp_mv,
+                                              step_param + n, x->sadperbit16,
+                                              &num00, &v_fn_ptr, x->mvcost,
+                                              ref_mv);
+            if ( tmp_err < INT_MAX-new_mv_mode_penalty )
+                tmp_err += new_mv_mode_penalty;
+
+            if (tmp_err < *best_motion_err)
+            {
+                *best_motion_err = tmp_err;
+                best_mv->row = tmp_mv.as_mv.row;
+                best_mv->col = tmp_mv.as_mv.col;
+            }
+        }
+    }
+}
+
+void vp8_first_pass(VP8_COMP *cpi)
+{
+    int mb_row, mb_col;
+    MACROBLOCK *const x = & cpi->mb;
+    VP8_COMMON *const cm = & cpi->common;
+    MACROBLOCKD *const xd = & x->e_mbd;
+
+    int recon_yoffset, recon_uvoffset;
+    YV12_BUFFER_CONFIG *lst_yv12 = &cm->yv12_fb[cm->lst_fb_idx];
+    YV12_BUFFER_CONFIG *new_yv12 = &cm->yv12_fb[cm->new_fb_idx];
+    YV12_BUFFER_CONFIG *gld_yv12 = &cm->yv12_fb[cm->gld_fb_idx];
+    int recon_y_stride = lst_yv12->y_stride;
+    int recon_uv_stride = lst_yv12->uv_stride;
+    int64_t intra_error = 0;
+    int64_t coded_error = 0;
+
+    int sum_mvr = 0, sum_mvc = 0;
+    int sum_mvr_abs = 0, sum_mvc_abs = 0;
+    int sum_mvrs = 0, sum_mvcs = 0;
+    int mvcount = 0;
+    int intercount = 0;
+    int second_ref_count = 0;
+    int intrapenalty = 256;
+    int neutral_count = 0;
+    int new_mv_count = 0;
+    int sum_in_vectors = 0;
+    uint32_t lastmv_as_int = 0;
+
+    int_mv zero_ref_mv;
+
+    zero_ref_mv.as_int = 0;
+
+    vp8_clear_system_state();
+
+    x->src = * cpi->Source;
+    xd->pre = *lst_yv12;
+    xd->dst = *new_yv12;
+
+    x->partition_info = x->pi;
+
+    xd->mode_info_context = cm->mi;
+
+    if(!cm->use_bilinear_mc_filter)
+    {
+         xd->subpixel_predict        = vp8_sixtap_predict4x4;
+         xd->subpixel_predict8x4     = vp8_sixtap_predict8x4;
+         xd->subpixel_predict8x8     = vp8_sixtap_predict8x8;
+         xd->subpixel_predict16x16   = vp8_sixtap_predict16x16;
+     }
+     else
+     {
+         xd->subpixel_predict        = vp8_bilinear_predict4x4;
+         xd->subpixel_predict8x4     = vp8_bilinear_predict8x4;
+         xd->subpixel_predict8x8     = vp8_bilinear_predict8x8;
+         xd->subpixel_predict16x16   = vp8_bilinear_predict16x16;
+     }
+
+    vp8_build_block_offsets(x);
+
+    /* set up frame new frame for intra coded blocks */
+    vp8_setup_intra_recon(new_yv12);
+    vp8cx_frame_init_quantizer(cpi);
+
+    /* Initialise the MV cost table to the defaults */
+    {
+        int flag[2] = {1, 1};
+        vp8_initialize_rd_consts(cpi, x, vp8_dc_quant(cm->base_qindex, cm->y1dc_delta_q));
+        memcpy(cm->fc.mvc, vp8_default_mv_context, sizeof(vp8_default_mv_context));
+        vp8_build_component_cost_table(cpi->mb.mvcost, (const MV_CONTEXT *) cm->fc.mvc, flag);
+    }
+
+    /* for each macroblock row in image */
+    for (mb_row = 0; mb_row < cm->mb_rows; mb_row++)
+    {
+        int_mv best_ref_mv;
+
+        best_ref_mv.as_int = 0;
+
+        /* reset above block coeffs */
+        xd->up_available = (mb_row != 0);
+        recon_yoffset = (mb_row * recon_y_stride * 16);
+        recon_uvoffset = (mb_row * recon_uv_stride * 8);
+
+        /* Set up limit values for motion vectors to prevent them extending
+         * outside the UMV borders
+         */
+        x->mv_row_min = -((mb_row * 16) + (VP8BORDERINPIXELS - 16));
+        x->mv_row_max = ((cm->mb_rows - 1 - mb_row) * 16) + (VP8BORDERINPIXELS - 16);
+
+
+        /* for each macroblock col in image */
+        for (mb_col = 0; mb_col < cm->mb_cols; mb_col++)
+        {
+            int this_error;
+            int gf_motion_error = INT_MAX;
+            int use_dc_pred = (mb_col || mb_row) && (!mb_col || !mb_row);
+
+            xd->dst.y_buffer = new_yv12->y_buffer + recon_yoffset;
+            xd->dst.u_buffer = new_yv12->u_buffer + recon_uvoffset;
+            xd->dst.v_buffer = new_yv12->v_buffer + recon_uvoffset;
+            xd->left_available = (mb_col != 0);
+
+            /* Copy current mb to a buffer */
+            vp8_copy_mem16x16(x->src.y_buffer, x->src.y_stride, x->thismb, 16);
+
+            /* do intra 16x16 prediction */
+            this_error = vp8_encode_intra(cpi, x, use_dc_pred);
+
+            /* "intrapenalty" below deals with situations where the intra
+             * and inter error scores are very low (eg a plain black frame)
+             * We do not have special cases in first pass for 0,0 and
+             * nearest etc so all inter modes carry an overhead cost
+             * estimate fot the mv. When the error score is very low this
+             * causes us to pick all or lots of INTRA modes and throw lots
+             * of key frames. This penalty adds a cost matching that of a
+             * 0,0 mv to the intra case.
+             */
+            this_error += intrapenalty;
+
+            /* Cumulative intra error total */
+            intra_error += (int64_t)this_error;
+
+            /* Set up limit values for motion vectors to prevent them
+             * extending outside the UMV borders
+             */
+            x->mv_col_min = -((mb_col * 16) + (VP8BORDERINPIXELS - 16));
+            x->mv_col_max = ((cm->mb_cols - 1 - mb_col) * 16) + (VP8BORDERINPIXELS - 16);
+
+            /* Other than for the first frame do a motion search */
+            if (cm->current_video_frame > 0)
+            {
+                BLOCKD *d = &x->e_mbd.block[0];
+                MV tmp_mv = {0, 0};
+                int tmp_err;
+                int motion_error = INT_MAX;
+                int raw_motion_error = INT_MAX;
+
+                /* Simple 0,0 motion with no mv overhead */
+                zz_motion_search( cpi, x, cpi->last_frame_unscaled_source,
+                                  &raw_motion_error, lst_yv12, &motion_error,
+                                  recon_yoffset );
+                d->bmi.mv.as_mv.row = 0;
+                d->bmi.mv.as_mv.col = 0;
+
+                if (raw_motion_error < cpi->oxcf.encode_breakout)
+                    goto skip_motion_search;
+
+                /* Test last reference frame using the previous best mv as the
+                 * starting point (best reference) for the search
+                 */
+                first_pass_motion_search(cpi, x, &best_ref_mv,
+                                        &d->bmi.mv.as_mv, lst_yv12,
+                                        &motion_error, recon_yoffset);
+
+                /* If the current best reference mv is not centred on 0,0
+                 * then do a 0,0 based search as well
+                 */
+                if (best_ref_mv.as_int)
+                {
+                   tmp_err = INT_MAX;
+                   first_pass_motion_search(cpi, x, &zero_ref_mv, &tmp_mv,
+                                     lst_yv12, &tmp_err, recon_yoffset);
+
+                   if ( tmp_err < motion_error )
+                   {
+                        motion_error = tmp_err;
+                        d->bmi.mv.as_mv.row = tmp_mv.row;
+                        d->bmi.mv.as_mv.col = tmp_mv.col;
+                   }
+                }
+
+                /* Experimental search in a second reference frame ((0,0)
+                 * based only)
+                 */
+                if (cm->current_video_frame > 1)
+                {
+                    first_pass_motion_search(cpi, x, &zero_ref_mv, &tmp_mv, gld_yv12, &gf_motion_error, recon_yoffset);
+
+                    if ((gf_motion_error < motion_error) && (gf_motion_error < this_error))
+                    {
+                        second_ref_count++;
+                    }
+
+                    /* Reset to last frame as reference buffer */
+                    xd->pre.y_buffer = lst_yv12->y_buffer + recon_yoffset;
+                    xd->pre.u_buffer = lst_yv12->u_buffer + recon_uvoffset;
+                    xd->pre.v_buffer = lst_yv12->v_buffer + recon_uvoffset;
+                }
+
+skip_motion_search:
+                /* Intra assumed best */
+                best_ref_mv.as_int = 0;
+
+                if (motion_error <= this_error)
+                {
+                    /* Keep a count of cases where the inter and intra were
+                     * very close and very low. This helps with scene cut
+                     * detection for example in cropped clips with black bars
+                     * at the sides or top and bottom.
+                     */
+                    if( (((this_error-intrapenalty) * 9) <=
+                         (motion_error*10)) &&
+                        (this_error < (2*intrapenalty)) )
+                    {
+                        neutral_count++;
+                    }
+
+                    d->bmi.mv.as_mv.row *= 8;
+                    d->bmi.mv.as_mv.col *= 8;
+                    this_error = motion_error;
+                    vp8_set_mbmode_and_mvs(x, NEWMV, &d->bmi.mv);
+                    vp8_encode_inter16x16y(x);
+                    sum_mvr += d->bmi.mv.as_mv.row;
+                    sum_mvr_abs += abs(d->bmi.mv.as_mv.row);
+                    sum_mvc += d->bmi.mv.as_mv.col;
+                    sum_mvc_abs += abs(d->bmi.mv.as_mv.col);
+                    sum_mvrs += d->bmi.mv.as_mv.row * d->bmi.mv.as_mv.row;
+                    sum_mvcs += d->bmi.mv.as_mv.col * d->bmi.mv.as_mv.col;
+                    intercount++;
+
+                    best_ref_mv.as_int = d->bmi.mv.as_int;
+
+                    /* Was the vector non-zero */
+                    if (d->bmi.mv.as_int)
+                    {
+                        mvcount++;
+
+                        /* Was it different from the last non zero vector */
+                        if ( d->bmi.mv.as_int != lastmv_as_int )
+                            new_mv_count++;
+                        lastmv_as_int = d->bmi.mv.as_int;
+
+                        /* Does the Row vector point inwards or outwards */
+                        if (mb_row < cm->mb_rows / 2)
+                        {
+                            if (d->bmi.mv.as_mv.row > 0)
+                                sum_in_vectors--;
+                            else if (d->bmi.mv.as_mv.row < 0)
+                                sum_in_vectors++;
+                        }
+                        else if (mb_row > cm->mb_rows / 2)
+                        {
+                            if (d->bmi.mv.as_mv.row > 0)
+                                sum_in_vectors++;
+                            else if (d->bmi.mv.as_mv.row < 0)
+                                sum_in_vectors--;
+                        }
+
+                        /* Does the Row vector point inwards or outwards */
+                        if (mb_col < cm->mb_cols / 2)
+                        {
+                            if (d->bmi.mv.as_mv.col > 0)
+                                sum_in_vectors--;
+                            else if (d->bmi.mv.as_mv.col < 0)
+                                sum_in_vectors++;
+                        }
+                        else if (mb_col > cm->mb_cols / 2)
+                        {
+                            if (d->bmi.mv.as_mv.col > 0)
+                                sum_in_vectors++;
+                            else if (d->bmi.mv.as_mv.col < 0)
+                                sum_in_vectors--;
+                        }
+                    }
+                }
+            }
+
+            coded_error += (int64_t)this_error;
+
+            /* adjust to the next column of macroblocks */
+            x->src.y_buffer += 16;
+            x->src.u_buffer += 8;
+            x->src.v_buffer += 8;
+
+            recon_yoffset += 16;
+            recon_uvoffset += 8;
+        }
+
+        /* adjust to the next row of mbs */
+        x->src.y_buffer += 16 * x->src.y_stride - 16 * cm->mb_cols;
+        x->src.u_buffer += 8 * x->src.uv_stride - 8 * cm->mb_cols;
+        x->src.v_buffer += 8 * x->src.uv_stride - 8 * cm->mb_cols;
+
+        /* extend the recon for intra prediction */
+        vp8_extend_mb_row(new_yv12, xd->dst.y_buffer + 16, xd->dst.u_buffer + 8, xd->dst.v_buffer + 8);
+        vp8_clear_system_state();
+    }
+
+    vp8_clear_system_state();
+    {
+        double weight = 0.0;
+
+        FIRSTPASS_STATS fps;
+
+        fps.frame      = cm->current_video_frame ;
+        fps.intra_error = (double)(intra_error >> 8);
+        fps.coded_error = (double)(coded_error >> 8);
+        weight = simple_weight(cpi->Source);
+
+
+        if (weight < 0.1)
+            weight = 0.1;
+
+        fps.ssim_weighted_pred_err = fps.coded_error * weight;
+
+        fps.pcnt_inter  = 0.0;
+        fps.pcnt_motion = 0.0;
+        fps.MVr        = 0.0;
+        fps.mvr_abs     = 0.0;
+        fps.MVc        = 0.0;
+        fps.mvc_abs     = 0.0;
+        fps.MVrv       = 0.0;
+        fps.MVcv       = 0.0;
+        fps.mv_in_out_count  = 0.0;
+        fps.new_mv_count = 0.0;
+        fps.count      = 1.0;
+
+        fps.pcnt_inter   = 1.0 * (double)intercount / cm->MBs;
+        fps.pcnt_second_ref = 1.0 * (double)second_ref_count / cm->MBs;
+        fps.pcnt_neutral = 1.0 * (double)neutral_count / cm->MBs;
+
+        if (mvcount > 0)
+        {
+            fps.MVr = (double)sum_mvr / (double)mvcount;
+            fps.mvr_abs = (double)sum_mvr_abs / (double)mvcount;
+            fps.MVc = (double)sum_mvc / (double)mvcount;
+            fps.mvc_abs = (double)sum_mvc_abs / (double)mvcount;
+            fps.MVrv = ((double)sum_mvrs - (fps.MVr * fps.MVr / (double)mvcount)) / (double)mvcount;
+            fps.MVcv = ((double)sum_mvcs - (fps.MVc * fps.MVc / (double)mvcount)) / (double)mvcount;
+            fps.mv_in_out_count = (double)sum_in_vectors / (double)(mvcount * 2);
+            fps.new_mv_count = new_mv_count;
+
+            fps.pcnt_motion = 1.0 * (double)mvcount / cpi->common.MBs;
+        }
+
+        /* TODO:  handle the case when duration is set to 0, or something less
+         * than the full time between subsequent cpi->source_time_stamps
+         */
+        fps.duration = (double)(cpi->source->ts_end
+                       - cpi->source->ts_start);
+
+        /* don't want to do output stats with a stack variable! */
+        memcpy(&cpi->twopass.this_frame_stats,
+               &fps,
+               sizeof(FIRSTPASS_STATS));
+        output_stats(cpi, cpi->output_pkt_list, &cpi->twopass.this_frame_stats);
+        accumulate_stats(&cpi->twopass.total_stats, &fps);
+    }
+
+    /* Copy the previous Last Frame into the GF buffer if specific
+     * conditions for doing so are met
+     */
+    if ((cm->current_video_frame > 0) &&
+        (cpi->twopass.this_frame_stats.pcnt_inter > 0.20) &&
+        ((cpi->twopass.this_frame_stats.intra_error /
+          DOUBLE_DIVIDE_CHECK(cpi->twopass.this_frame_stats.coded_error)) >
+         2.0))
+    {
+        vp8_yv12_copy_frame(lst_yv12, gld_yv12);
+    }
+
+    /* swap frame pointers so last frame refers to the frame we just
+     * compressed
+     */
+    vp8_swap_yv12_buffer(lst_yv12, new_yv12);
+    vp8_yv12_extend_frame_borders(lst_yv12);
+
+    /* Special case for the first frame. Copy into the GF buffer as a
+     * second reference.
+     */
+    if (cm->current_video_frame == 0)
+    {
+        vp8_yv12_copy_frame(lst_yv12, gld_yv12);
+    }
+
+
+    /* use this to see what the first pass reconstruction looks like */
+    if (0)
+    {
+        char filename[512];
+        FILE *recon_file;
+        sprintf(filename, "enc%04d.yuv", (int) cm->current_video_frame);
+
+        if (cm->current_video_frame == 0)
+            recon_file = fopen(filename, "wb");
+        else
+            recon_file = fopen(filename, "ab");
+
+        (void) fwrite(lst_yv12->buffer_alloc, lst_yv12->frame_size, 1,
+                      recon_file);
+        fclose(recon_file);
+    }
+
+    cm->current_video_frame++;
+
+}
+extern const int vp8_bits_per_mb[2][QINDEX_RANGE];
+
+/* Estimate a cost per mb attributable to overheads such as the coding of
+ * modes and motion vectors.
+ * Currently simplistic in its assumptions for testing.
+ */
+
+static double bitcost( double prob )
+{
+  if (prob > 0.000122)
+    return -log(prob) / log(2.0);
+  else
+    return 13.0;
+}
+static int64_t estimate_modemvcost(VP8_COMP *cpi,
+                                     FIRSTPASS_STATS * fpstats)
+{
+    int mv_cost;
+    int64_t mode_cost;
+
+    double av_pct_inter = fpstats->pcnt_inter / fpstats->count;
+    double av_pct_motion = fpstats->pcnt_motion / fpstats->count;
+    double av_intra = (1.0 - av_pct_inter);
+
+    double zz_cost;
+    double motion_cost;
+    double intra_cost;
+
+    zz_cost = bitcost(av_pct_inter - av_pct_motion);
+    motion_cost = bitcost(av_pct_motion);
+    intra_cost = bitcost(av_intra);
+
+    /* Estimate of extra bits per mv overhead for mbs
+     * << 9 is the normalization to the (bits * 512) used in vp8_bits_per_mb
+     */
+    mv_cost = ((int)(fpstats->new_mv_count / fpstats->count) * 8) << 9;
+
+    /* Crude estimate of overhead cost from modes
+     * << 9 is the normalization to (bits * 512) used in vp8_bits_per_mb
+     */
+    mode_cost = (int64_t)((((av_pct_inter - av_pct_motion) * zz_cost) +
+                             (av_pct_motion * motion_cost) +
+                             (av_intra * intra_cost)) * cpi->common.MBs) * 512;
+
+    return mv_cost + mode_cost;
+}
+
+static double calc_correction_factor( double err_per_mb,
+                                      double err_devisor,
+                                      double pt_low,
+                                      double pt_high,
+                                      int Q )
+{
+    double power_term;
+    double error_term = err_per_mb / err_devisor;
+    double correction_factor;
+
+    /* Adjustment based on Q to power term. */
+    power_term = pt_low + (Q * 0.01);
+    power_term = (power_term > pt_high) ? pt_high : power_term;
+
+    /* Adjustments to error term */
+    /* TBD */
+
+    /* Calculate correction factor */
+    correction_factor = pow(error_term, power_term);
+
+    /* Clip range */
+    correction_factor =
+        (correction_factor < 0.05)
+            ? 0.05 : (correction_factor > 5.0) ? 5.0 : correction_factor;
+
+    return correction_factor;
+}
+
+static int estimate_max_q(VP8_COMP *cpi,
+                          FIRSTPASS_STATS * fpstats,
+                          int section_target_bandwitdh,
+                          int overhead_bits )
+{
+    int Q;
+    int num_mbs = cpi->common.MBs;
+    int target_norm_bits_per_mb;
+
+    double section_err = (fpstats->coded_error / fpstats->count);
+    double err_per_mb = section_err / num_mbs;
+    double err_correction_factor;
+    double speed_correction = 1.0;
+    int overhead_bits_per_mb;
+
+    if (section_target_bandwitdh <= 0)
+        return cpi->twopass.maxq_max_limit;       /* Highest value allowed */
+
+    target_norm_bits_per_mb =
+        (section_target_bandwitdh < (1 << 20))
+            ? (512 * section_target_bandwitdh) / num_mbs
+            : 512 * (section_target_bandwitdh / num_mbs);
+
+    /* Calculate a corrective factor based on a rolling ratio of bits spent
+     * vs target bits
+     */
+    if ((cpi->rolling_target_bits > 0) &&
+        (cpi->active_worst_quality < cpi->worst_quality))
+    {
+        double rolling_ratio;
+
+        rolling_ratio = (double)cpi->rolling_actual_bits /
+                        (double)cpi->rolling_target_bits;
+
+        if (rolling_ratio < 0.95)
+            cpi->twopass.est_max_qcorrection_factor -= 0.005;
+        else if (rolling_ratio > 1.05)
+            cpi->twopass.est_max_qcorrection_factor += 0.005;
+
+        cpi->twopass.est_max_qcorrection_factor =
+            (cpi->twopass.est_max_qcorrection_factor < 0.1)
+                ? 0.1
+                : (cpi->twopass.est_max_qcorrection_factor > 10.0)
+                    ? 10.0 : cpi->twopass.est_max_qcorrection_factor;
+    }
+
+    /* Corrections for higher compression speed settings
+     * (reduced compression expected)
+     */
+    if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
+    {
+        if (cpi->oxcf.cpu_used <= 5)
+            speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
+        else
+            speed_correction = 1.25;
+    }
+
+    /* Estimate of overhead bits per mb */
+    /* Correction to overhead bits for min allowed Q. */
+    overhead_bits_per_mb = overhead_bits / num_mbs;
+    overhead_bits_per_mb = (int)(overhead_bits_per_mb *
+                            pow( 0.98, (double)cpi->twopass.maxq_min_limit ));
+
+    /* Try and pick a max Q that will be high enough to encode the
+     * content at the given rate.
+     */
+    for (Q = cpi->twopass.maxq_min_limit; Q < cpi->twopass.maxq_max_limit; Q++)
+    {
+        int bits_per_mb_at_this_q;
+
+        /* Error per MB based correction factor */
+        err_correction_factor =
+            calc_correction_factor(err_per_mb, 150.0, 0.40, 0.90, Q);
+
+        bits_per_mb_at_this_q =
+            vp8_bits_per_mb[INTER_FRAME][Q] + overhead_bits_per_mb;
+
+        bits_per_mb_at_this_q = (int)(.5 + err_correction_factor
+            * speed_correction * cpi->twopass.est_max_qcorrection_factor
+            * cpi->twopass.section_max_qfactor
+            * (double)bits_per_mb_at_this_q);
+
+        /* Mode and motion overhead */
+        /* As Q rises in real encode loop rd code will force overhead down
+         * We make a crude adjustment for this here as *.98 per Q step.
+         */
+        overhead_bits_per_mb = (int)((double)overhead_bits_per_mb * 0.98);
+
+        if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
+            break;
+    }
+
+    /* Restriction on active max q for constrained quality mode. */
+    if ( (cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY) &&
+         (Q < cpi->cq_target_quality) )
+    {
+        Q = cpi->cq_target_quality;
+    }
+
+    /* Adjust maxq_min_limit and maxq_max_limit limits based on
+     * average q observed in clip for non kf/gf.arf frames
+     * Give average a chance to settle though.
+     */
+    if ( (cpi->ni_frames >
+                  ((int)cpi->twopass.total_stats.count >> 8)) &&
+         (cpi->ni_frames > 150) )
+    {
+        cpi->twopass.maxq_max_limit = ((cpi->ni_av_qi + 32) < cpi->worst_quality)
+                                  ? (cpi->ni_av_qi + 32) : cpi->worst_quality;
+        cpi->twopass.maxq_min_limit = ((cpi->ni_av_qi - 32) > cpi->best_quality)
+                                  ? (cpi->ni_av_qi - 32) : cpi->best_quality;
+    }
+
+    return Q;
+}
+
+/* For cq mode estimate a cq level that matches the observed
+ * complexity and data rate.
+ */
+static int estimate_cq( VP8_COMP *cpi,
+                        FIRSTPASS_STATS * fpstats,
+                        int section_target_bandwitdh,
+                        int overhead_bits )
+{
+    int Q;
+    int num_mbs = cpi->common.MBs;
+    int target_norm_bits_per_mb;
+
+    double section_err = (fpstats->coded_error / fpstats->count);
+    double err_per_mb = section_err / num_mbs;
+    double err_correction_factor;
+    double speed_correction = 1.0;
+    double clip_iiratio;
+    double clip_iifactor;
+    int overhead_bits_per_mb;
+
+    if (0)
+    {
+        FILE *f = fopen("epmp.stt", "a");
+        fprintf(f, "%10.2f\n", err_per_mb );
+        fclose(f);
+    }
+
+    target_norm_bits_per_mb = (section_target_bandwitdh < (1 << 20))
+                              ? (512 * section_target_bandwitdh) / num_mbs
+                              : 512 * (section_target_bandwitdh / num_mbs);
+
+    /* Estimate of overhead bits per mb */
+    overhead_bits_per_mb = overhead_bits / num_mbs;
+
+    /* Corrections for higher compression speed settings
+     * (reduced compression expected)
+     */
+    if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
+    {
+        if (cpi->oxcf.cpu_used <= 5)
+            speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
+        else
+            speed_correction = 1.25;
+    }
+
+    /* II ratio correction factor for clip as a whole */
+    clip_iiratio = cpi->twopass.total_stats.intra_error /
+                   DOUBLE_DIVIDE_CHECK(cpi->twopass.total_stats.coded_error);
+    clip_iifactor = 1.0 - ((clip_iiratio - 10.0) * 0.025);
+    if (clip_iifactor < 0.80)
+        clip_iifactor = 0.80;
+
+    /* Try and pick a Q that can encode the content at the given rate. */
+    for (Q = 0; Q < MAXQ; Q++)
+    {
+        int bits_per_mb_at_this_q;
+
+        /* Error per MB based correction factor */
+        err_correction_factor =
+            calc_correction_factor(err_per_mb, 100.0, 0.40, 0.90, Q);
+
+        bits_per_mb_at_this_q =
+            vp8_bits_per_mb[INTER_FRAME][Q] + overhead_bits_per_mb;
+
+        bits_per_mb_at_this_q =
+            (int)( .5 + err_correction_factor *
+                        speed_correction *
+                        clip_iifactor *
+                        (double)bits_per_mb_at_this_q);
+
+        /* Mode and motion overhead */
+        /* As Q rises in real encode loop rd code will force overhead down
+         * We make a crude adjustment for this here as *.98 per Q step.
+         */
+        overhead_bits_per_mb = (int)((double)overhead_bits_per_mb * 0.98);
+
+        if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
+            break;
+    }
+
+    /* Clip value to range "best allowed to (worst allowed - 1)" */
+    Q = cq_level[Q];
+    if ( Q >= cpi->worst_quality )
+        Q = cpi->worst_quality - 1;
+    if ( Q < cpi->best_quality )
+        Q = cpi->best_quality;
+
+    return Q;
+}
+
+static int estimate_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh)
+{
+    int Q;
+    int num_mbs = cpi->common.MBs;
+    int target_norm_bits_per_mb;
+
+    double err_per_mb = section_err / num_mbs;
+    double err_correction_factor;
+    double speed_correction = 1.0;
+
+    target_norm_bits_per_mb = (section_target_bandwitdh < (1 << 20)) ? (512 * section_target_bandwitdh) / num_mbs : 512 * (section_target_bandwitdh / num_mbs);
+
+    /* Corrections for higher compression speed settings
+     * (reduced compression expected)
+     */
+    if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
+    {
+        if (cpi->oxcf.cpu_used <= 5)
+            speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
+        else
+            speed_correction = 1.25;
+    }
+
+    /* Try and pick a Q that can encode the content at the given rate. */
+    for (Q = 0; Q < MAXQ; Q++)
+    {
+        int bits_per_mb_at_this_q;
+
+        /* Error per MB based correction factor */
+        err_correction_factor =
+            calc_correction_factor(err_per_mb, 150.0, 0.40, 0.90, Q);
+
+        bits_per_mb_at_this_q =
+            (int)( .5 + ( err_correction_factor *
+                          speed_correction *
+                          cpi->twopass.est_max_qcorrection_factor *
+                          (double)vp8_bits_per_mb[INTER_FRAME][Q] / 1.0 ) );
+
+        if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
+            break;
+    }
+
+    return Q;
+}
+
+/* Estimate a worst case Q for a KF group */
+static int estimate_kf_group_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh, double group_iiratio)
+{
+    int Q;
+    int num_mbs = cpi->common.MBs;
+    int target_norm_bits_per_mb = (512 * section_target_bandwitdh) / num_mbs;
+    int bits_per_mb_at_this_q;
+
+    double err_per_mb = section_err / num_mbs;
+    double err_correction_factor;
+    double speed_correction = 1.0;
+    double current_spend_ratio = 1.0;
+
+    double pow_highq = (POW1 < 0.6) ? POW1 + 0.3 : 0.90;
+    double pow_lowq = (POW1 < 0.7) ? POW1 + 0.1 : 0.80;
+
+    double iiratio_correction_factor = 1.0;
+
+    double combined_correction_factor;
+
+    /* Trap special case where the target is <= 0 */
+    if (target_norm_bits_per_mb <= 0)
+        return MAXQ * 2;
+
+    /* Calculate a corrective factor based on a rolling ratio of bits spent
+     *  vs target bits
+     * This is clamped to the range 0.1 to 10.0
+     */
+    if (cpi->long_rolling_target_bits <= 0)
+        current_spend_ratio = 10.0;
+    else
+    {
+        current_spend_ratio = (double)cpi->long_rolling_actual_bits / (double)cpi->long_rolling_target_bits;
+        current_spend_ratio = (current_spend_ratio > 10.0) ? 10.0 : (current_spend_ratio < 0.1) ? 0.1 : current_spend_ratio;
+    }
+
+    /* Calculate a correction factor based on the quality of prediction in
+     * the sequence as indicated by intra_inter error score ratio (IIRatio)
+     * The idea here is to favour subsampling in the hardest sections vs
+     * the easyest.
+     */
+    iiratio_correction_factor = 1.0 - ((group_iiratio - 6.0) * 0.1);
+
+    if (iiratio_correction_factor < 0.5)
+        iiratio_correction_factor = 0.5;
+
+    /* Corrections for higher compression speed settings
+     * (reduced compression expected)
+     */
+    if ((cpi->compressor_speed == 3) || (cpi->compressor_speed == 1))
+    {
+        if (cpi->oxcf.cpu_used <= 5)
+            speed_correction = 1.04 + (cpi->oxcf.cpu_used * 0.04);
+        else
+            speed_correction = 1.25;
+    }
+
+    /* Combine the various factors calculated above */
+    combined_correction_factor = speed_correction * iiratio_correction_factor * current_spend_ratio;
+
+    /* Try and pick a Q that should be high enough to encode the content at
+     * the given rate.
+     */
+    for (Q = 0; Q < MAXQ; Q++)
+    {
+        /* Error per MB based correction factor */
+        err_correction_factor =
+            calc_correction_factor(err_per_mb, 150.0, pow_lowq, pow_highq, Q);
+
+        bits_per_mb_at_this_q =
+            (int)(.5 + ( err_correction_factor *
+                         combined_correction_factor *
+                         (double)vp8_bits_per_mb[INTER_FRAME][Q]) );
+
+        if (bits_per_mb_at_this_q <= target_norm_bits_per_mb)
+            break;
+    }
+
+    /* If we could not hit the target even at Max Q then estimate what Q
+     * would have been required
+     */
+    while ((bits_per_mb_at_this_q > target_norm_bits_per_mb)  && (Q < (MAXQ * 2)))
+    {
+
+        bits_per_mb_at_this_q = (int)(0.96 * bits_per_mb_at_this_q);
+        Q++;
+    }
+
+    if (0)
+    {
+        FILE *f = fopen("estkf_q.stt", "a");
+        fprintf(f, "%8d %8d %8d %8.2f %8.3f %8.2f %8.3f %8.3f %8.3f %8d\n", cpi->common.current_video_frame, bits_per_mb_at_this_q,
+                target_norm_bits_per_mb, err_per_mb, err_correction_factor,
+                current_spend_ratio, group_iiratio, iiratio_correction_factor,
+                (double)cpi->buffer_level / (double)cpi->oxcf.optimal_buffer_level, Q);
+        fclose(f);
+    }
+
+    return Q;
+}
+
+void vp8_init_second_pass(VP8_COMP *cpi)
+{
+    FIRSTPASS_STATS this_frame;
+    FIRSTPASS_STATS *start_pos;
+
+    double two_pass_min_rate = (double)(cpi->oxcf.target_bandwidth * cpi->oxcf.two_pass_vbrmin_section / 100);
+
+    zero_stats(&cpi->twopass.total_stats);
+    zero_stats(&cpi->twopass.total_left_stats);
+
+    if (!cpi->twopass.stats_in_end)
+        return;
+
+    cpi->twopass.total_stats = *cpi->twopass.stats_in_end;
+    cpi->twopass.total_left_stats = cpi->twopass.total_stats;
+
+    /* each frame can have a different duration, as the frame rate in the
+     * source isn't guaranteed to be constant.   The frame rate prior to
+     * the first frame encoded in the second pass is a guess.  However the
+     * sum duration is not. Its calculated based on the actual durations of
+     * all frames from the first pass.
+     */
+    vp8_new_framerate(cpi, 10000000.0 * cpi->twopass.total_stats.count / cpi->twopass.total_stats.duration);
+
+    cpi->output_framerate = cpi->framerate;
+    cpi->twopass.bits_left = (int64_t)(cpi->twopass.total_stats.duration * cpi->oxcf.target_bandwidth / 10000000.0) ;
+    cpi->twopass.bits_left -= (int64_t)(cpi->twopass.total_stats.duration * two_pass_min_rate / 10000000.0);
+
+    /* Calculate a minimum intra value to be used in determining the IIratio
+     * scores used in the second pass. We have this minimum to make sure
+     * that clips that are static but "low complexity" in the intra domain
+     * are still boosted appropriately for KF/GF/ARF
+     */
+    cpi->twopass.kf_intra_err_min = KF_MB_INTRA_MIN * cpi->common.MBs;
+    cpi->twopass.gf_intra_err_min = GF_MB_INTRA_MIN * cpi->common.MBs;
+
+    /* Scan the first pass file and calculate an average Intra / Inter error
+     * score ratio for the sequence
+     */
+    {
+        double sum_iiratio = 0.0;
+        double IIRatio;
+
+        start_pos = cpi->twopass.stats_in; /* Note starting "file" position */
+
+        while (input_stats(cpi, &this_frame) != EOF)
+        {
+            IIRatio = this_frame.intra_error / DOUBLE_DIVIDE_CHECK(this_frame.coded_error);
+            IIRatio = (IIRatio < 1.0) ? 1.0 : (IIRatio > 20.0) ? 20.0 : IIRatio;
+            sum_iiratio += IIRatio;
+        }
+
+        cpi->twopass.avg_iiratio = sum_iiratio / DOUBLE_DIVIDE_CHECK((double)cpi->twopass.total_stats.count);
+
+        /* Reset file position */
+        reset_fpf_position(cpi, start_pos);
+    }
+
+    /* Scan the first pass file and calculate a modified total error based
+     * upon the bias/power function used to allocate bits
+     */
+    {
+        start_pos = cpi->twopass.stats_in;  /* Note starting "file" position */
+
+        cpi->twopass.modified_error_total = 0.0;
+        cpi->twopass.modified_error_used = 0.0;
+
+        while (input_stats(cpi, &this_frame) != EOF)
+        {
+            cpi->twopass.modified_error_total += calculate_modified_err(cpi, &this_frame);
+        }
+        cpi->twopass.modified_error_left = cpi->twopass.modified_error_total;
+
+        reset_fpf_position(cpi, start_pos);  /* Reset file position */
+
+    }
+}
+
+void vp8_end_second_pass(VP8_COMP *cpi)
+{
+  (void)cpi;
+}
+
+/* This function gives and estimate of how badly we believe the prediction
+ * quality is decaying from frame to frame.
+ */
+static double get_prediction_decay_rate(VP8_COMP *cpi, FIRSTPASS_STATS *next_frame)
+{
+    double prediction_decay_rate;
+    double motion_decay;
+    double motion_pct = next_frame->pcnt_motion;
+    (void)cpi;
+
+    /* Initial basis is the % mbs inter coded */
+    prediction_decay_rate = next_frame->pcnt_inter;
+
+    /* High % motion -> somewhat higher decay rate */
+    motion_decay = (1.0 - (motion_pct / 20.0));
+    if (motion_decay < prediction_decay_rate)
+        prediction_decay_rate = motion_decay;
+
+    /* Adjustment to decay rate based on speed of motion */
+    {
+        double this_mv_rabs;
+        double this_mv_cabs;
+        double distance_factor;
+
+        this_mv_rabs = fabs(next_frame->mvr_abs * motion_pct);
+        this_mv_cabs = fabs(next_frame->mvc_abs * motion_pct);
+
+        distance_factor = sqrt((this_mv_rabs * this_mv_rabs) +
+                               (this_mv_cabs * this_mv_cabs)) / 250.0;
+        distance_factor = ((distance_factor > 1.0)
+                                ? 0.0 : (1.0 - distance_factor));
+        if (distance_factor < prediction_decay_rate)
+            prediction_decay_rate = distance_factor;
+    }
+
+    return prediction_decay_rate;
+}
+
+/* Function to test for a condition where a complex transition is followed
+ * by a static section. For example in slide shows where there is a fade
+ * between slides. This is to help with more optimal kf and gf positioning.
+ */
+static int detect_transition_to_still(
+    VP8_COMP *cpi,
+    int frame_interval,
+    int still_interval,
+    double loop_decay_rate,
+    double decay_accumulator )
+{
+    int trans_to_still = 0;
+
+    /* Break clause to detect very still sections after motion
+     * For example a static image after a fade or other transition
+     * instead of a clean scene cut.
+     */
+    if ( (frame_interval > MIN_GF_INTERVAL) &&
+         (loop_decay_rate >= 0.999) &&
+         (decay_accumulator < 0.9) )
+    {
+        int j;
+        FIRSTPASS_STATS * position = cpi->twopass.stats_in;
+        FIRSTPASS_STATS tmp_next_frame;
+        double decay_rate;
+
+        /* Look ahead a few frames to see if static condition persists... */
+        for ( j = 0; j < still_interval; j++ )
+        {
+            if (EOF == input_stats(cpi, &tmp_next_frame))
+                break;
+
+            decay_rate = get_prediction_decay_rate(cpi, &tmp_next_frame);
+            if ( decay_rate < 0.999 )
+                break;
+        }
+        /* Reset file position */
+        reset_fpf_position(cpi, position);
+
+        /* Only if it does do we signal a transition to still */
+        if ( j == still_interval )
+            trans_to_still = 1;
+    }
+
+    return trans_to_still;
+}
+
+/* This function detects a flash through the high relative pcnt_second_ref
+ * score in the frame following a flash frame. The offset passed in should
+ * reflect this
+ */
+static int detect_flash( VP8_COMP *cpi, int offset )
+{
+    FIRSTPASS_STATS next_frame;
+
+    int flash_detected = 0;
+
+    /* Read the frame data. */
+    /* The return is 0 (no flash detected) if not a valid frame */
+    if ( read_frame_stats(cpi, &next_frame, offset) != EOF )
+    {
+        /* What we are looking for here is a situation where there is a
+         * brief break in prediction (such as a flash) but subsequent frames
+         * are reasonably well predicted by an earlier (pre flash) frame.
+         * The recovery after a flash is indicated by a high pcnt_second_ref
+         * comapred to pcnt_inter.
+         */
+        if ( (next_frame.pcnt_second_ref > next_frame.pcnt_inter) &&
+             (next_frame.pcnt_second_ref >= 0.5 ) )
+        {
+            flash_detected = 1;
+
+            /*if (1)
+            {
+                FILE *f = fopen("flash.stt", "a");
+                fprintf(f, "%8.0f %6.2f %6.2f\n",
+                    next_frame.frame,
+                    next_frame.pcnt_inter,
+                    next_frame.pcnt_second_ref);
+                fclose(f);
+            }*/
+        }
+    }
+
+    return flash_detected;
+}
+
+/* Update the motion related elements to the GF arf boost calculation */
+static void accumulate_frame_motion_stats(
+    VP8_COMP *cpi,
+    FIRSTPASS_STATS * this_frame,
+    double * this_frame_mv_in_out,
+    double * mv_in_out_accumulator,
+    double * abs_mv_in_out_accumulator,
+    double * mv_ratio_accumulator )
+{
+    double this_frame_mvr_ratio;
+    double this_frame_mvc_ratio;
+    double motion_pct;
+    (void)cpi;
+
+    /* Accumulate motion stats. */
+    motion_pct = this_frame->pcnt_motion;
+
+    /* Accumulate Motion In/Out of frame stats */
+    *this_frame_mv_in_out = this_frame->mv_in_out_count * motion_pct;
+    *mv_in_out_accumulator += this_frame->mv_in_out_count * motion_pct;
+    *abs_mv_in_out_accumulator +=
+        fabs(this_frame->mv_in_out_count * motion_pct);
+
+    /* Accumulate a measure of how uniform (or conversely how random)
+     * the motion field is. (A ratio of absmv / mv)
+     */
+    if (motion_pct > 0.05)
+    {
+        this_frame_mvr_ratio = fabs(this_frame->mvr_abs) /
+                               DOUBLE_DIVIDE_CHECK(fabs(this_frame->MVr));
+
+        this_frame_mvc_ratio = fabs(this_frame->mvc_abs) /
+                               DOUBLE_DIVIDE_CHECK(fabs(this_frame->MVc));
+
+         *mv_ratio_accumulator +=
+            (this_frame_mvr_ratio < this_frame->mvr_abs)
+                ? (this_frame_mvr_ratio * motion_pct)
+                : this_frame->mvr_abs * motion_pct;
+
+        *mv_ratio_accumulator +=
+            (this_frame_mvc_ratio < this_frame->mvc_abs)
+                ? (this_frame_mvc_ratio * motion_pct)
+                : this_frame->mvc_abs * motion_pct;
+
+    }
+}
+
+/* Calculate a baseline boost number for the current frame. */
+static double calc_frame_boost(
+    VP8_COMP *cpi,
+    FIRSTPASS_STATS * this_frame,
+    double this_frame_mv_in_out )
+{
+    double frame_boost;
+
+    /* Underlying boost factor is based on inter intra error ratio */
+    if (this_frame->intra_error > cpi->twopass.gf_intra_err_min)
+        frame_boost = (IIFACTOR * this_frame->intra_error /
+                      DOUBLE_DIVIDE_CHECK(this_frame->coded_error));
+    else
+        frame_boost = (IIFACTOR * cpi->twopass.gf_intra_err_min /
+                      DOUBLE_DIVIDE_CHECK(this_frame->coded_error));
+
+    /* Increase boost for frames where new data coming into frame
+     * (eg zoom out). Slightly reduce boost if there is a net balance
+     * of motion out of the frame (zoom in).
+     * The range for this_frame_mv_in_out is -1.0 to +1.0
+     */
+    if (this_frame_mv_in_out > 0.0)
+        frame_boost += frame_boost * (this_frame_mv_in_out * 2.0);
+    /* In extreme case boost is halved */
+    else
+        frame_boost += frame_boost * (this_frame_mv_in_out / 2.0);
+
+    /* Clip to maximum */
+    if (frame_boost > GF_RMAX)
+        frame_boost = GF_RMAX;
+
+    return frame_boost;
+}
+
+#if NEW_BOOST
+static int calc_arf_boost(
+    VP8_COMP *cpi,
+    int offset,
+    int f_frames,
+    int b_frames,
+    int *f_boost,
+    int *b_boost )
+{
+    FIRSTPASS_STATS this_frame;
+
+    int i;
+    double boost_score = 0.0;
+    double mv_ratio_accumulator = 0.0;
+    double decay_accumulator = 1.0;
+    double this_frame_mv_in_out = 0.0;
+    double mv_in_out_accumulator = 0.0;
+    double abs_mv_in_out_accumulator = 0.0;
+    double r;
+    int flash_detected = 0;
+
+    /* Search forward from the proposed arf/next gf position */
+    for ( i = 0; i < f_frames; i++ )
+    {
+        if ( read_frame_stats(cpi, &this_frame, (i+offset)) == EOF )
+            break;
+
+        /* Update the motion related elements to the boost calculation */
+        accumulate_frame_motion_stats( cpi, &this_frame,
+            &this_frame_mv_in_out, &mv_in_out_accumulator,
+            &abs_mv_in_out_accumulator, &mv_ratio_accumulator );
+
+        /* Calculate the baseline boost number for this frame */
+        r = calc_frame_boost( cpi, &this_frame, this_frame_mv_in_out );
+
+        /* We want to discount the the flash frame itself and the recovery
+         * frame that follows as both will have poor scores.
+         */
+        flash_detected = detect_flash(cpi, (i+offset)) ||
+                         detect_flash(cpi, (i+offset+1));
+
+        /* Cumulative effect of prediction quality decay */
+        if ( !flash_detected )
+        {
+            decay_accumulator =
+                decay_accumulator *
+                get_prediction_decay_rate(cpi, &this_frame);
+            decay_accumulator =
+                decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
+        }
+        boost_score += (decay_accumulator * r);
+
+        /* Break out conditions. */
+        if  ( (!flash_detected) &&
+              ((mv_ratio_accumulator > 100.0) ||
+               (abs_mv_in_out_accumulator > 3.0) ||
+               (mv_in_out_accumulator < -2.0) ) )
+        {
+            break;
+        }
+    }
+
+    *f_boost = (int)(boost_score * 100.0) >> 4;
+
+    /* Reset for backward looking loop */
+    boost_score = 0.0;
+    mv_ratio_accumulator = 0.0;
+    decay_accumulator = 1.0;
+    this_frame_mv_in_out = 0.0;
+    mv_in_out_accumulator = 0.0;
+    abs_mv_in_out_accumulator = 0.0;
+
+    /* Search forward from the proposed arf/next gf position */
+    for ( i = -1; i >= -b_frames; i-- )
+    {
+        if ( read_frame_stats(cpi, &this_frame, (i+offset)) == EOF )
+            break;
+
+        /* Update the motion related elements to the boost calculation */
+        accumulate_frame_motion_stats( cpi, &this_frame,
+            &this_frame_mv_in_out, &mv_in_out_accumulator,
+            &abs_mv_in_out_accumulator, &mv_ratio_accumulator );
+
+        /* Calculate the baseline boost number for this frame */
+        r = calc_frame_boost( cpi, &this_frame, this_frame_mv_in_out );
+
+        /* We want to discount the the flash frame itself and the recovery
+         * frame that follows as both will have poor scores.
+         */
+        flash_detected = detect_flash(cpi, (i+offset)) ||
+                         detect_flash(cpi, (i+offset+1));
+
+        /* Cumulative effect of prediction quality decay */
+        if ( !flash_detected )
+        {
+            decay_accumulator =
+                decay_accumulator *
+                get_prediction_decay_rate(cpi, &this_frame);
+            decay_accumulator =
+                decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
+        }
+
+        boost_score += (decay_accumulator * r);
+
+        /* Break out conditions. */
+        if  ( (!flash_detected) &&
+              ((mv_ratio_accumulator > 100.0) ||
+               (abs_mv_in_out_accumulator > 3.0) ||
+               (mv_in_out_accumulator < -2.0) ) )
+        {
+            break;
+        }
+    }
+    *b_boost = (int)(boost_score * 100.0) >> 4;
+
+    return (*f_boost + *b_boost);
+}
+#endif
+
+/* Analyse and define a gf/arf group . */
+static void define_gf_group(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
+{
+    FIRSTPASS_STATS next_frame;
+    FIRSTPASS_STATS *start_pos;
+    int i;
+    double r;
+    double boost_score = 0.0;
+    double old_boost_score = 0.0;
+    double gf_group_err = 0.0;
+    double gf_first_frame_err = 0.0;
+    double mod_frame_err = 0.0;
+
+    double mv_ratio_accumulator = 0.0;
+    double decay_accumulator = 1.0;
+
+    double loop_decay_rate = 1.00;          /* Starting decay rate */
+
+    double this_frame_mv_in_out = 0.0;
+    double mv_in_out_accumulator = 0.0;
+    double abs_mv_in_out_accumulator = 0.0;
+    double mod_err_per_mb_accumulator = 0.0;
+
+    int max_bits = frame_max_bits(cpi);     /* Max for a single frame */
+
+    unsigned int allow_alt_ref =
+                    cpi->oxcf.play_alternate && cpi->oxcf.lag_in_frames;
+
+    int alt_boost = 0;
+    int f_boost = 0;
+    int b_boost = 0;
+    int flash_detected;
+
+    cpi->twopass.gf_group_bits = 0;
+    cpi->twopass.gf_decay_rate = 0;
+
+    vp8_clear_system_state();
+
+    start_pos = cpi->twopass.stats_in;
+
+    memset(&next_frame, 0, sizeof(next_frame)); /* assure clean */
+
+    /* Load stats for the current frame. */
+    mod_frame_err = calculate_modified_err(cpi, this_frame);
+
+    /* Note the error of the frame at the start of the group (this will be
+     * the GF frame error if we code a normal gf
+     */
+    gf_first_frame_err = mod_frame_err;
+
+    /* Special treatment if the current frame is a key frame (which is also
+     * a gf). If it is then its error score (and hence bit allocation) need
+     * to be subtracted out from the calculation for the GF group
+     */
+    if (cpi->common.frame_type == KEY_FRAME)
+        gf_group_err -= gf_first_frame_err;
+
+    /* Scan forward to try and work out how many frames the next gf group
+     * should contain and what level of boost is appropriate for the GF
+     * or ARF that will be coded with the group
+     */
+    i = 0;
+
+    while (((i < cpi->twopass.static_scene_max_gf_interval) ||
+            ((cpi->twopass.frames_to_key - i) < MIN_GF_INTERVAL)) &&
+           (i < cpi->twopass.frames_to_key))
+    {
+        i++;
+
+        /* Accumulate error score of frames in this gf group */
+        mod_frame_err = calculate_modified_err(cpi, this_frame);
+
+        gf_group_err += mod_frame_err;
+
+        mod_err_per_mb_accumulator +=
+            mod_frame_err / DOUBLE_DIVIDE_CHECK((double)cpi->common.MBs);
+
+        if (EOF == input_stats(cpi, &next_frame))
+            break;
+
+        /* Test for the case where there is a brief flash but the prediction
+         * quality back to an earlier frame is then restored.
+         */
+        flash_detected = detect_flash(cpi, 0);
+
+        /* Update the motion related elements to the boost calculation */
+        accumulate_frame_motion_stats( cpi, &next_frame,
+            &this_frame_mv_in_out, &mv_in_out_accumulator,
+            &abs_mv_in_out_accumulator, &mv_ratio_accumulator );
+
+        /* Calculate a baseline boost number for this frame */
+        r = calc_frame_boost( cpi, &next_frame, this_frame_mv_in_out );
+
+        /* Cumulative effect of prediction quality decay */
+        if ( !flash_detected )
+        {
+            loop_decay_rate = get_prediction_decay_rate(cpi, &next_frame);
+            decay_accumulator = decay_accumulator * loop_decay_rate;
+            decay_accumulator =
+                decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
+        }
+        boost_score += (decay_accumulator * r);
+
+        /* Break clause to detect very still sections after motion
+         * For example a staic image after a fade or other transition.
+         */
+        if ( detect_transition_to_still( cpi, i, 5,
+                                         loop_decay_rate,
+                                         decay_accumulator ) )
+        {
+            allow_alt_ref = 0;
+            boost_score = old_boost_score;
+            break;
+        }
+
+        /* Break out conditions. */
+        if  (
+            /* Break at cpi->max_gf_interval unless almost totally static */
+            (i >= cpi->max_gf_interval && (decay_accumulator < 0.995)) ||
+            (
+                /* Dont break out with a very short interval */
+                (i > MIN_GF_INTERVAL) &&
+                /* Dont break out very close to a key frame */
+                ((cpi->twopass.frames_to_key - i) >= MIN_GF_INTERVAL) &&
+                ((boost_score > 20.0) || (next_frame.pcnt_inter < 0.75)) &&
+                (!flash_detected) &&
+                ((mv_ratio_accumulator > 100.0) ||
+                 (abs_mv_in_out_accumulator > 3.0) ||
+                 (mv_in_out_accumulator < -2.0) ||
+                 ((boost_score - old_boost_score) < 2.0))
+            ) )
+        {
+            boost_score = old_boost_score;
+            break;
+        }
+
+        memcpy(this_frame, &next_frame, sizeof(*this_frame));
+
+        old_boost_score = boost_score;
+    }
+
+    cpi->twopass.gf_decay_rate =
+        (i > 0) ? (int)(100.0 * (1.0 - decay_accumulator)) / i : 0;
+
+    /* When using CBR apply additional buffer related upper limits */
+    if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+    {
+        double max_boost;
+
+        /* For cbr apply buffer related limits */
+        if (cpi->drop_frames_allowed)
+        {
+            int64_t df_buffer_level = cpi->oxcf.drop_frames_water_mark *
+                                  (cpi->oxcf.optimal_buffer_level / 100);
+
+            if (cpi->buffer_level > df_buffer_level)
+                max_boost = ((double)((cpi->buffer_level - df_buffer_level) * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
+            else
+                max_boost = 0.0;
+        }
+        else if (cpi->buffer_level > 0)
+        {
+            max_boost = ((double)(cpi->buffer_level * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
+        }
+        else
+        {
+            max_boost = 0.0;
+        }
+
+        if (boost_score > max_boost)
+            boost_score = max_boost;
+    }
+
+    /* Dont allow conventional gf too near the next kf */
+    if ((cpi->twopass.frames_to_key - i) < MIN_GF_INTERVAL)
+    {
+        while (i < cpi->twopass.frames_to_key)
+        {
+            i++;
+
+            if (EOF == input_stats(cpi, this_frame))
+                break;
+
+            if (i < cpi->twopass.frames_to_key)
+            {
+                mod_frame_err = calculate_modified_err(cpi, this_frame);
+                gf_group_err += mod_frame_err;
+            }
+        }
+    }
+
+    cpi->gfu_boost = (int)(boost_score * 100.0) >> 4;
+
+#if NEW_BOOST
+    /* Alterrnative boost calculation for alt ref */
+    alt_boost = calc_arf_boost( cpi, 0, (i-1), (i-1), &f_boost, &b_boost );
+#endif
+
+    /* Should we use the alternate refernce frame */
+    if (allow_alt_ref &&
+        (i >= MIN_GF_INTERVAL) &&
+        /* dont use ARF very near next kf */
+        (i <= (cpi->twopass.frames_to_key - MIN_GF_INTERVAL)) &&
+#if NEW_BOOST
+        ((next_frame.pcnt_inter > 0.75) ||
+         (next_frame.pcnt_second_ref > 0.5)) &&
+        ((mv_in_out_accumulator / (double)i > -0.2) ||
+         (mv_in_out_accumulator > -2.0)) &&
+        (b_boost > 100) &&
+        (f_boost > 100) )
+#else
+        (next_frame.pcnt_inter > 0.75) &&
+        ((mv_in_out_accumulator / (double)i > -0.2) ||
+         (mv_in_out_accumulator > -2.0)) &&
+        (cpi->gfu_boost > 100) &&
+        (cpi->twopass.gf_decay_rate <=
+            (ARF_DECAY_THRESH + (cpi->gfu_boost / 200))) )
+#endif
+    {
+        int Boost;
+        int allocation_chunks;
+        int Q = (cpi->oxcf.fixed_q < 0)
+                ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
+        int tmp_q;
+        int arf_frame_bits = 0;
+        int group_bits;
+
+#if NEW_BOOST
+        cpi->gfu_boost = alt_boost;
+#endif
+
+        /* Estimate the bits to be allocated to the group as a whole */
+        if ((cpi->twopass.kf_group_bits > 0) &&
+            (cpi->twopass.kf_group_error_left > 0))
+        {
+            group_bits = (int)((double)cpi->twopass.kf_group_bits *
+                (gf_group_err / (double)cpi->twopass.kf_group_error_left));
+        }
+        else
+            group_bits = 0;
+
+        /* Boost for arf frame */
+#if NEW_BOOST
+        Boost = (alt_boost * GFQ_ADJUSTMENT) / 100;
+#else
+        Boost = (cpi->gfu_boost * 3 * GFQ_ADJUSTMENT) / (2 * 100);
+#endif
+        Boost += (i * 50);
+
+        /* Set max and minimum boost and hence minimum allocation */
+        if (Boost > ((cpi->baseline_gf_interval + 1) * 200))
+            Boost = ((cpi->baseline_gf_interval + 1) * 200);
+        else if (Boost < 125)
+            Boost = 125;
+
+        allocation_chunks = (i * 100) + Boost;
+
+        /* Normalize Altboost and allocations chunck down to prevent overflow */
+        while (Boost > 1000)
+        {
+            Boost /= 2;
+            allocation_chunks /= 2;
+        }
+
+        /* Calculate the number of bits to be spent on the arf based on the
+         * boost number
+         */
+        arf_frame_bits = (int)((double)Boost * (group_bits /
+                               (double)allocation_chunks));
+
+        /* Estimate if there are enough bits available to make worthwhile use
+         * of an arf.
+         */
+        tmp_q = estimate_q(cpi, mod_frame_err, (int)arf_frame_bits);
+
+        /* Only use an arf if it is likely we will be able to code
+         * it at a lower Q than the surrounding frames.
+         */
+        if (tmp_q < cpi->worst_quality)
+        {
+            int half_gf_int;
+            int frames_after_arf;
+            int frames_bwd = cpi->oxcf.arnr_max_frames - 1;
+            int frames_fwd = cpi->oxcf.arnr_max_frames - 1;
+
+            cpi->source_alt_ref_pending = 1;
+
+            /*
+             * For alt ref frames the error score for the end frame of the
+             * group (the alt ref frame) should not contribute to the group
+             * total and hence the number of bit allocated to the group.
+             * Rather it forms part of the next group (it is the GF at the
+             * start of the next group)
+             * gf_group_err -= mod_frame_err;
+             *
+             * For alt ref frames alt ref frame is technically part of the
+             * GF frame for the next group but we always base the error
+             * calculation and bit allocation on the current group of frames.
+             *
+             * Set the interval till the next gf or arf.
+             * For ARFs this is the number of frames to be coded before the
+             * future frame that is coded as an ARF.
+             * The future frame itself is part of the next group
+             */
+            cpi->baseline_gf_interval = i;
+
+            /*
+             * Define the arnr filter width for this group of frames:
+             * We only filter frames that lie within a distance of half
+             * the GF interval from the ARF frame. We also have to trap
+             * cases where the filter extends beyond the end of clip.
+             * Note: this_frame->frame has been updated in the loop
+             * so it now points at the ARF frame.
+             */
+            half_gf_int = cpi->baseline_gf_interval >> 1;
+            frames_after_arf = (int)(cpi->twopass.total_stats.count -
+                               this_frame->frame - 1);
+
+            switch (cpi->oxcf.arnr_type)
+            {
+            case 1: /* Backward filter */
+                frames_fwd = 0;
+                if (frames_bwd > half_gf_int)
+                    frames_bwd = half_gf_int;
+                break;
+
+            case 2: /* Forward filter */
+                if (frames_fwd > half_gf_int)
+                    frames_fwd = half_gf_int;
+                if (frames_fwd > frames_after_arf)
+                    frames_fwd = frames_after_arf;
+                frames_bwd = 0;
+                break;
+
+            case 3: /* Centered filter */
+            default:
+                frames_fwd >>= 1;
+                if (frames_fwd > frames_after_arf)
+                    frames_fwd = frames_after_arf;
+                if (frames_fwd > half_gf_int)
+                    frames_fwd = half_gf_int;
+
+                frames_bwd = frames_fwd;
+
+                /* For even length filter there is one more frame backward
+                 * than forward: e.g. len=6 ==> bbbAff, len=7 ==> bbbAfff.
+                 */
+                if (frames_bwd < half_gf_int)
+                    frames_bwd += (cpi->oxcf.arnr_max_frames+1) & 0x1;
+                break;
+            }
+
+            cpi->active_arnr_frames = frames_bwd + 1 + frames_fwd;
+        }
+        else
+        {
+            cpi->source_alt_ref_pending = 0;
+            cpi->baseline_gf_interval = i;
+        }
+    }
+    else
+    {
+        cpi->source_alt_ref_pending = 0;
+        cpi->baseline_gf_interval = i;
+    }
+
+    /*
+     * Now decide how many bits should be allocated to the GF group as  a
+     * proportion of those remaining in the kf group.
+     * The final key frame group in the clip is treated as a special case
+     * where cpi->twopass.kf_group_bits is tied to cpi->twopass.bits_left.
+     * This is also important for short clips where there may only be one
+     * key frame.
+     */
+    if (cpi->twopass.frames_to_key >= (int)(cpi->twopass.total_stats.count -
+                                            cpi->common.current_video_frame))
+    {
+        cpi->twopass.kf_group_bits =
+            (cpi->twopass.bits_left > 0) ? cpi->twopass.bits_left : 0;
+    }
+
+    /* Calculate the bits to be allocated to the group as a whole */
+    if ((cpi->twopass.kf_group_bits > 0) &&
+        (cpi->twopass.kf_group_error_left > 0))
+    {
+        cpi->twopass.gf_group_bits =
+            (int64_t)(cpi->twopass.kf_group_bits *
+                      (gf_group_err / cpi->twopass.kf_group_error_left));
+    }
+    else
+        cpi->twopass.gf_group_bits = 0;
+
+    cpi->twopass.gf_group_bits =
+        (cpi->twopass.gf_group_bits < 0)
+            ? 0
+            : (cpi->twopass.gf_group_bits > cpi->twopass.kf_group_bits)
+                ? cpi->twopass.kf_group_bits : cpi->twopass.gf_group_bits;
+
+    /* Clip cpi->twopass.gf_group_bits based on user supplied data rate
+     * variability limit (cpi->oxcf.two_pass_vbrmax_section)
+     */
+    if (cpi->twopass.gf_group_bits >
+        (int64_t)max_bits * cpi->baseline_gf_interval)
+        cpi->twopass.gf_group_bits =
+            (int64_t)max_bits * cpi->baseline_gf_interval;
+
+    /* Reset the file position */
+    reset_fpf_position(cpi, start_pos);
+
+    /* Update the record of error used so far (only done once per gf group) */
+    cpi->twopass.modified_error_used += gf_group_err;
+
+    /* Assign  bits to the arf or gf. */
+    for (i = 0; i <= (cpi->source_alt_ref_pending && cpi->common.frame_type != KEY_FRAME); i++) {
+        int Boost;
+        int allocation_chunks;
+        int Q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME] : cpi->oxcf.fixed_q;
+        int gf_bits;
+
+        /* For ARF frames */
+        if (cpi->source_alt_ref_pending && i == 0)
+        {
+#if NEW_BOOST
+            Boost = (alt_boost * GFQ_ADJUSTMENT) / 100;
+#else
+            Boost = (cpi->gfu_boost * 3 * GFQ_ADJUSTMENT) / (2 * 100);
+#endif
+            Boost += (cpi->baseline_gf_interval * 50);
+
+            /* Set max and minimum boost and hence minimum allocation */
+            if (Boost > ((cpi->baseline_gf_interval + 1) * 200))
+                Boost = ((cpi->baseline_gf_interval + 1) * 200);
+            else if (Boost < 125)
+                Boost = 125;
+
+            allocation_chunks =
+                ((cpi->baseline_gf_interval + 1) * 100) + Boost;
+        }
+        /* Else for standard golden frames */
+        else
+        {
+            /* boost based on inter / intra ratio of subsequent frames */
+            Boost = (cpi->gfu_boost * GFQ_ADJUSTMENT) / 100;
+
+            /* Set max and minimum boost and hence minimum allocation */
+            if (Boost > (cpi->baseline_gf_interval * 150))
+                Boost = (cpi->baseline_gf_interval * 150);
+            else if (Boost < 125)
+                Boost = 125;
+
+            allocation_chunks =
+                (cpi->baseline_gf_interval * 100) + (Boost - 100);
+        }
+
+        /* Normalize Altboost and allocations chunck down to prevent overflow */
+        while (Boost > 1000)
+        {
+            Boost /= 2;
+            allocation_chunks /= 2;
+        }
+
+        /* Calculate the number of bits to be spent on the gf or arf based on
+         * the boost number
+         */
+        gf_bits = (int)((double)Boost *
+                        (cpi->twopass.gf_group_bits /
+                         (double)allocation_chunks));
+
+        /* If the frame that is to be boosted is simpler than the average for
+         * the gf/arf group then use an alternative calculation
+         * based on the error score of the frame itself
+         */
+        if (mod_frame_err < gf_group_err / (double)cpi->baseline_gf_interval)
+        {
+            double  alt_gf_grp_bits;
+            int     alt_gf_bits;
+
+            alt_gf_grp_bits =
+                (double)cpi->twopass.kf_group_bits  *
+                (mod_frame_err * (double)cpi->baseline_gf_interval) /
+                DOUBLE_DIVIDE_CHECK((double)cpi->twopass.kf_group_error_left);
+
+            alt_gf_bits = (int)((double)Boost * (alt_gf_grp_bits /
+                                                 (double)allocation_chunks));
+
+            if (gf_bits > alt_gf_bits)
+            {
+                gf_bits = alt_gf_bits;
+            }
+        }
+        /* Else if it is harder than other frames in the group make sure it at
+         * least receives an allocation in keeping with its relative error
+         * score, otherwise it may be worse off than an "un-boosted" frame
+         */
+        else
+        {
+            int alt_gf_bits =
+                (int)((double)cpi->twopass.kf_group_bits *
+                      mod_frame_err /
+                      DOUBLE_DIVIDE_CHECK((double)cpi->twopass.kf_group_error_left));
+
+            if (alt_gf_bits > gf_bits)
+            {
+                gf_bits = alt_gf_bits;
+            }
+        }
+
+        /* Apply an additional limit for CBR */
+        if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+        {
+            if (cpi->twopass.gf_bits > (int)(cpi->buffer_level >> 1))
+                cpi->twopass.gf_bits = (int)(cpi->buffer_level >> 1);
+        }
+
+        /* Dont allow a negative value for gf_bits */
+        if (gf_bits < 0)
+            gf_bits = 0;
+
+        /* Add in minimum for a frame */
+        gf_bits += cpi->min_frame_bandwidth;
+
+        if (i == 0)
+        {
+            cpi->twopass.gf_bits = gf_bits;
+        }
+        if (i == 1 || (!cpi->source_alt_ref_pending && (cpi->common.frame_type != KEY_FRAME)))
+        {
+            /* Per frame bit target for this frame */
+            cpi->per_frame_bandwidth = gf_bits;
+        }
+    }
+
+    {
+        /* Adjust KF group bits and error remainin */
+        cpi->twopass.kf_group_error_left -= (int64_t)gf_group_err;
+        cpi->twopass.kf_group_bits -= cpi->twopass.gf_group_bits;
+
+        if (cpi->twopass.kf_group_bits < 0)
+            cpi->twopass.kf_group_bits = 0;
+
+        /* Note the error score left in the remaining frames of the group.
+         * For normal GFs we want to remove the error score for the first
+         * frame of the group (except in Key frame case where this has
+         * already happened)
+         */
+        if (!cpi->source_alt_ref_pending && cpi->common.frame_type != KEY_FRAME)
+            cpi->twopass.gf_group_error_left = (int)(gf_group_err -
+                                                     gf_first_frame_err);
+        else
+            cpi->twopass.gf_group_error_left = (int) gf_group_err;
+
+        cpi->twopass.gf_group_bits -= cpi->twopass.gf_bits - cpi->min_frame_bandwidth;
+
+        if (cpi->twopass.gf_group_bits < 0)
+            cpi->twopass.gf_group_bits = 0;
+
+        /* This condition could fail if there are two kfs very close together
+         * despite (MIN_GF_INTERVAL) and would cause a devide by 0 in the
+         * calculation of cpi->twopass.alt_extra_bits.
+         */
+        if ( cpi->baseline_gf_interval >= 3 )
+        {
+#if NEW_BOOST
+            int boost = (cpi->source_alt_ref_pending)
+                        ? b_boost : cpi->gfu_boost;
+#else
+            int boost = cpi->gfu_boost;
+#endif
+            if ( boost >= 150 )
+            {
+                int pct_extra;
+
+                pct_extra = (boost - 100) / 50;
+                pct_extra = (pct_extra > 20) ? 20 : pct_extra;
+
+                cpi->twopass.alt_extra_bits =
+                    (int)(cpi->twopass.gf_group_bits * pct_extra) / 100;
+                cpi->twopass.gf_group_bits -= cpi->twopass.alt_extra_bits;
+                cpi->twopass.alt_extra_bits /=
+                    ((cpi->baseline_gf_interval-1)>>1);
+            }
+            else
+                cpi->twopass.alt_extra_bits = 0;
+        }
+        else
+            cpi->twopass.alt_extra_bits = 0;
+    }
+
+    /* Adjustments based on a measure of complexity of the section */
+    if (cpi->common.frame_type != KEY_FRAME)
+    {
+        FIRSTPASS_STATS sectionstats;
+        double Ratio;
+
+        zero_stats(&sectionstats);
+        reset_fpf_position(cpi, start_pos);
+
+        for (i = 0 ; i < cpi->baseline_gf_interval ; i++)
+        {
+            input_stats(cpi, &next_frame);
+            accumulate_stats(&sectionstats, &next_frame);
+        }
+
+        avg_stats(&sectionstats);
+
+        cpi->twopass.section_intra_rating = (unsigned int)
+            (sectionstats.intra_error /
+            DOUBLE_DIVIDE_CHECK(sectionstats.coded_error));
+
+        Ratio = sectionstats.intra_error / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error);
+        cpi->twopass.section_max_qfactor = 1.0 - ((Ratio - 10.0) * 0.025);
+
+        if (cpi->twopass.section_max_qfactor < 0.80)
+            cpi->twopass.section_max_qfactor = 0.80;
+
+        reset_fpf_position(cpi, start_pos);
+    }
+}
+
+/* Allocate bits to a normal frame that is neither a gf an arf or a key frame. */
+static void assign_std_frame_bits(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
+{
+    int    target_frame_size;
+
+    double modified_err;
+    double err_fraction;
+
+    int max_bits = frame_max_bits(cpi);  /* Max for a single frame */
+
+    /* Calculate modified prediction error used in bit allocation */
+    modified_err = calculate_modified_err(cpi, this_frame);
+
+    /* What portion of the remaining GF group error is used by this frame */
+    if (cpi->twopass.gf_group_error_left > 0)
+        err_fraction = modified_err / cpi->twopass.gf_group_error_left;
+    else
+        err_fraction = 0.0;
+
+    /* How many of those bits available for allocation should we give it? */
+    target_frame_size = (int)((double)cpi->twopass.gf_group_bits * err_fraction);
+
+    /* Clip to target size to 0 - max_bits (or cpi->twopass.gf_group_bits)
+     * at the top end.
+     */
+    if (target_frame_size < 0)
+        target_frame_size = 0;
+    else
+    {
+        if (target_frame_size > max_bits)
+            target_frame_size = max_bits;
+
+        if (target_frame_size > cpi->twopass.gf_group_bits)
+            target_frame_size = (int)cpi->twopass.gf_group_bits;
+    }
+
+    /* Adjust error and bits remaining */
+    cpi->twopass.gf_group_error_left -= (int)modified_err;
+    cpi->twopass.gf_group_bits -= target_frame_size;
+
+    if (cpi->twopass.gf_group_bits < 0)
+        cpi->twopass.gf_group_bits = 0;
+
+    /* Add in the minimum number of bits that is set aside for every frame. */
+    target_frame_size += cpi->min_frame_bandwidth;
+
+    /* Every other frame gets a few extra bits */
+    if ( (cpi->frames_since_golden & 0x01) &&
+         (cpi->frames_till_gf_update_due > 0) )
+    {
+        target_frame_size += cpi->twopass.alt_extra_bits;
+    }
+
+    /* Per frame bit target for this frame */
+    cpi->per_frame_bandwidth = target_frame_size;
+}
+
+void vp8_second_pass(VP8_COMP *cpi)
+{
+    int tmp_q;
+    int frames_left = (int)(cpi->twopass.total_stats.count - cpi->common.current_video_frame);
+
+    FIRSTPASS_STATS this_frame = {0};
+    FIRSTPASS_STATS this_frame_copy;
+
+    double this_frame_intra_error;
+    double this_frame_coded_error;
+
+    int overhead_bits;
+
+    if (!cpi->twopass.stats_in)
+    {
+        return ;
+    }
+
+    vp8_clear_system_state();
+
+    if (EOF == input_stats(cpi, &this_frame))
+        return;
+
+    this_frame_intra_error = this_frame.intra_error;
+    this_frame_coded_error = this_frame.coded_error;
+
+    /* keyframe and section processing ! */
+    if (cpi->twopass.frames_to_key == 0)
+    {
+        /* Define next KF group and assign bits to it */
+        memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
+        find_next_key_frame(cpi, &this_frame_copy);
+
+        /* Special case: Error error_resilient_mode mode does not make much
+         * sense for two pass but with its current meaning this code is
+         * designed to stop outlandish behaviour if someone does set it when
+         * using two pass. It effectively disables GF groups. This is
+         * temporary code until we decide what should really happen in this
+         * case.
+         */
+        if (cpi->oxcf.error_resilient_mode)
+        {
+            cpi->twopass.gf_group_bits = cpi->twopass.kf_group_bits;
+            cpi->twopass.gf_group_error_left =
+                                  (int)cpi->twopass.kf_group_error_left;
+            cpi->baseline_gf_interval = cpi->twopass.frames_to_key;
+            cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
+            cpi->source_alt_ref_pending = 0;
+        }
+
+    }
+
+    /* Is this a GF / ARF (Note that a KF is always also a GF) */
+    if (cpi->frames_till_gf_update_due == 0)
+    {
+        /* Define next gf group and assign bits to it */
+        memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
+        define_gf_group(cpi, &this_frame_copy);
+
+        /* If we are going to code an altref frame at the end of the group
+         * and the current frame is not a key frame.... If the previous
+         * group used an arf this frame has already benefited from that arf
+         * boost and it should not be given extra bits If the previous
+         * group was NOT coded using arf we may want to apply some boost to
+         * this GF as well
+         */
+        if (cpi->source_alt_ref_pending && (cpi->common.frame_type != KEY_FRAME))
+        {
+            /* Assign a standard frames worth of bits from those allocated
+             * to the GF group
+             */
+            int bak = cpi->per_frame_bandwidth;
+            memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
+            assign_std_frame_bits(cpi, &this_frame_copy);
+            cpi->per_frame_bandwidth = bak;
+        }
+    }
+
+    /* Otherwise this is an ordinary frame */
+    else
+    {
+        /* Special case: Error error_resilient_mode mode does not make much
+         * sense for two pass but with its current meaning but this code is
+         * designed to stop outlandish behaviour if someone does set it
+         * when using two pass. It effectively disables GF groups. This is
+         * temporary code till we decide what should really happen in this
+         * case.
+         */
+        if (cpi->oxcf.error_resilient_mode)
+        {
+            cpi->frames_till_gf_update_due = cpi->twopass.frames_to_key;
+
+            if (cpi->common.frame_type != KEY_FRAME)
+            {
+                /* Assign bits from those allocated to the GF group */
+                memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
+                assign_std_frame_bits(cpi, &this_frame_copy);
+            }
+        }
+        else
+        {
+            /* Assign bits from those allocated to the GF group */
+            memcpy(&this_frame_copy, &this_frame, sizeof(this_frame));
+            assign_std_frame_bits(cpi, &this_frame_copy);
+        }
+    }
+
+    /* Keep a globally available copy of this and the next frame's iiratio. */
+    cpi->twopass.this_iiratio = (unsigned int)(this_frame_intra_error /
+                        DOUBLE_DIVIDE_CHECK(this_frame_coded_error));
+    {
+        FIRSTPASS_STATS next_frame;
+        if ( lookup_next_frame_stats(cpi, &next_frame) != EOF )
+        {
+            cpi->twopass.next_iiratio = (unsigned int)(next_frame.intra_error /
+                                DOUBLE_DIVIDE_CHECK(next_frame.coded_error));
+        }
+    }
+
+    /* Set nominal per second bandwidth for this frame */
+    cpi->target_bandwidth = (int)
+    (cpi->per_frame_bandwidth * cpi->output_framerate);
+    if (cpi->target_bandwidth < 0)
+        cpi->target_bandwidth = 0;
+
+
+    /* Account for mv, mode and other overheads. */
+    overhead_bits = (int)estimate_modemvcost(
+                        cpi, &cpi->twopass.total_left_stats );
+
+    /* Special case code for first frame. */
+    if (cpi->common.current_video_frame == 0)
+    {
+        cpi->twopass.est_max_qcorrection_factor = 1.0;
+
+        /* Set a cq_level in constrained quality mode. */
+        if ( cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY )
+        {
+            int est_cq;
+
+            est_cq =
+                estimate_cq( cpi,
+                             &cpi->twopass.total_left_stats,
+                             (int)(cpi->twopass.bits_left / frames_left),
+                             overhead_bits );
+
+            cpi->cq_target_quality = cpi->oxcf.cq_level;
+            if ( est_cq > cpi->cq_target_quality )
+                cpi->cq_target_quality = est_cq;
+        }
+
+        /* guess at maxq needed in 2nd pass */
+        cpi->twopass.maxq_max_limit = cpi->worst_quality;
+        cpi->twopass.maxq_min_limit = cpi->best_quality;
+
+        tmp_q = estimate_max_q(
+                    cpi,
+                    &cpi->twopass.total_left_stats,
+                    (int)(cpi->twopass.bits_left / frames_left),
+                    overhead_bits );
+
+        /* Limit the maxq value returned subsequently.
+         * This increases the risk of overspend or underspend if the initial
+         * estimate for the clip is bad, but helps prevent excessive
+         * variation in Q, especially near the end of a clip
+         * where for example a small overspend may cause Q to crash
+         */
+        cpi->twopass.maxq_max_limit = ((tmp_q + 32) < cpi->worst_quality)
+                                  ? (tmp_q + 32) : cpi->worst_quality;
+        cpi->twopass.maxq_min_limit = ((tmp_q - 32) > cpi->best_quality)
+                                  ? (tmp_q - 32) : cpi->best_quality;
+
+        cpi->active_worst_quality         = tmp_q;
+        cpi->ni_av_qi                     = tmp_q;
+    }
+
+    /* The last few frames of a clip almost always have to few or too many
+     * bits and for the sake of over exact rate control we dont want to make
+     * radical adjustments to the allowed quantizer range just to use up a
+     * few surplus bits or get beneath the target rate.
+     */
+    else if ( (cpi->common.current_video_frame <
+                 (((unsigned int)cpi->twopass.total_stats.count * 255)>>8)) &&
+              ((cpi->common.current_video_frame + cpi->baseline_gf_interval) <
+                 (unsigned int)cpi->twopass.total_stats.count) )
+    {
+        if (frames_left < 1)
+            frames_left = 1;
+
+        tmp_q = estimate_max_q(
+                    cpi,
+                    &cpi->twopass.total_left_stats,
+                    (int)(cpi->twopass.bits_left / frames_left),
+                    overhead_bits );
+
+        /* Move active_worst_quality but in a damped way */
+        if (tmp_q > cpi->active_worst_quality)
+            cpi->active_worst_quality ++;
+        else if (tmp_q < cpi->active_worst_quality)
+            cpi->active_worst_quality --;
+
+        cpi->active_worst_quality =
+            ((cpi->active_worst_quality * 3) + tmp_q + 2) / 4;
+    }
+
+    cpi->twopass.frames_to_key --;
+
+    /* Update the total stats remaining sturcture */
+    subtract_stats(&cpi->twopass.total_left_stats, &this_frame );
+}
+
+
+static int test_candidate_kf(VP8_COMP *cpi,  FIRSTPASS_STATS *last_frame, FIRSTPASS_STATS *this_frame, FIRSTPASS_STATS *next_frame)
+{
+    int is_viable_kf = 0;
+
+    /* Does the frame satisfy the primary criteria of a key frame
+     *      If so, then examine how well it predicts subsequent frames
+     */
+    if ((this_frame->pcnt_second_ref < 0.10) &&
+        (next_frame->pcnt_second_ref < 0.10) &&
+        ((this_frame->pcnt_inter < 0.05) ||
+         (
+             ((this_frame->pcnt_inter - this_frame->pcnt_neutral) < .25) &&
+             ((this_frame->intra_error / DOUBLE_DIVIDE_CHECK(this_frame->coded_error)) < 2.5) &&
+             ((fabs(last_frame->coded_error - this_frame->coded_error) / DOUBLE_DIVIDE_CHECK(this_frame->coded_error) > .40) ||
+              (fabs(last_frame->intra_error - this_frame->intra_error) / DOUBLE_DIVIDE_CHECK(this_frame->intra_error) > .40) ||
+              ((next_frame->intra_error / DOUBLE_DIVIDE_CHECK(next_frame->coded_error)) > 3.5)
+             )
+         )
+        )
+       )
+    {
+        int i;
+        FIRSTPASS_STATS *start_pos;
+
+        FIRSTPASS_STATS local_next_frame;
+
+        double boost_score = 0.0;
+        double old_boost_score = 0.0;
+        double decay_accumulator = 1.0;
+        double next_iiratio;
+
+        memcpy(&local_next_frame, next_frame, sizeof(*next_frame));
+
+        /* Note the starting file position so we can reset to it */
+        start_pos = cpi->twopass.stats_in;
+
+        /* Examine how well the key frame predicts subsequent frames */
+        for (i = 0 ; i < 16; i++)
+        {
+            next_iiratio = (IIKFACTOR1 * local_next_frame.intra_error / DOUBLE_DIVIDE_CHECK(local_next_frame.coded_error)) ;
+
+            if (next_iiratio > RMAX)
+                next_iiratio = RMAX;
+
+            /* Cumulative effect of decay in prediction quality */
+            if (local_next_frame.pcnt_inter > 0.85)
+                decay_accumulator = decay_accumulator * local_next_frame.pcnt_inter;
+            else
+                decay_accumulator = decay_accumulator * ((0.85 + local_next_frame.pcnt_inter) / 2.0);
+
+            /* Keep a running total */
+            boost_score += (decay_accumulator * next_iiratio);
+
+            /* Test various breakout clauses */
+            if ((local_next_frame.pcnt_inter < 0.05) ||
+                (next_iiratio < 1.5) ||
+                (((local_next_frame.pcnt_inter -
+                   local_next_frame.pcnt_neutral) < 0.20) &&
+                 (next_iiratio < 3.0)) ||
+                ((boost_score - old_boost_score) < 0.5) ||
+                (local_next_frame.intra_error < 200)
+               )
+            {
+                break;
+            }
+
+            old_boost_score = boost_score;
+
+            /* Get the next frame details */
+            if (EOF == input_stats(cpi, &local_next_frame))
+                break;
+        }
+
+        /* If there is tolerable prediction for at least the next 3 frames
+         * then break out else discard this pottential key frame and move on
+         */
+        if (boost_score > 5.0 && (i > 3))
+            is_viable_kf = 1;
+        else
+        {
+            /* Reset the file position */
+            reset_fpf_position(cpi, start_pos);
+
+            is_viable_kf = 0;
+        }
+    }
+
+    return is_viable_kf;
+}
+static void find_next_key_frame(VP8_COMP *cpi, FIRSTPASS_STATS *this_frame)
+{
+    int i,j;
+    FIRSTPASS_STATS last_frame;
+    FIRSTPASS_STATS first_frame;
+    FIRSTPASS_STATS next_frame;
+    FIRSTPASS_STATS *start_position;
+
+    double decay_accumulator = 1.0;
+    double boost_score = 0;
+    double old_boost_score = 0.0;
+    double loop_decay_rate;
+
+    double kf_mod_err = 0.0;
+    double kf_group_err = 0.0;
+    double kf_group_intra_err = 0.0;
+    double kf_group_coded_err = 0.0;
+    double recent_loop_decay[8] = {1.0,1.0,1.0,1.0,1.0,1.0,1.0,1.0};
+
+    memset(&next_frame, 0, sizeof(next_frame));
+
+    vp8_clear_system_state();
+    start_position = cpi->twopass.stats_in;
+
+    cpi->common.frame_type = KEY_FRAME;
+
+    /* is this a forced key frame by interval */
+    cpi->this_key_frame_forced = cpi->next_key_frame_forced;
+
+    /* Clear the alt ref active flag as this can never be active on a key
+     * frame
+     */
+    cpi->source_alt_ref_active = 0;
+
+    /* Kf is always a gf so clear frames till next gf counter */
+    cpi->frames_till_gf_update_due = 0;
+
+    cpi->twopass.frames_to_key = 1;
+
+    /* Take a copy of the initial frame details */
+    memcpy(&first_frame, this_frame, sizeof(*this_frame));
+
+    cpi->twopass.kf_group_bits = 0;
+    cpi->twopass.kf_group_error_left = 0;
+
+    kf_mod_err = calculate_modified_err(cpi, this_frame);
+
+    /* find the next keyframe */
+    i = 0;
+    while (cpi->twopass.stats_in < cpi->twopass.stats_in_end)
+    {
+        /* Accumulate kf group error */
+        kf_group_err += calculate_modified_err(cpi, this_frame);
+
+        /* These figures keep intra and coded error counts for all frames
+         * including key frames in the group. The effect of the key frame
+         * itself can be subtracted out using the first_frame data
+         * collected above
+         */
+        kf_group_intra_err += this_frame->intra_error;
+        kf_group_coded_err += this_frame->coded_error;
+
+        /* Load the next frame's stats. */
+        memcpy(&last_frame, this_frame, sizeof(*this_frame));
+        input_stats(cpi, this_frame);
+
+        /* Provided that we are not at the end of the file... */
+        if (cpi->oxcf.auto_key
+            && lookup_next_frame_stats(cpi, &next_frame) != EOF)
+        {
+            /* Normal scene cut check */
+            if ( ( i >= MIN_GF_INTERVAL ) &&
+                 test_candidate_kf(cpi, &last_frame, this_frame, &next_frame) )
+            {
+                break;
+            }
+
+            /* How fast is prediction quality decaying */
+            loop_decay_rate = get_prediction_decay_rate(cpi, &next_frame);
+
+            /* We want to know something about the recent past... rather than
+             * as used elsewhere where we are concened with decay in prediction
+             * quality since the last GF or KF.
+             */
+            recent_loop_decay[i%8] = loop_decay_rate;
+            decay_accumulator = 1.0;
+            for (j = 0; j < 8; j++)
+            {
+                decay_accumulator = decay_accumulator * recent_loop_decay[j];
+            }
+
+            /* Special check for transition or high motion followed by a
+             * static scene.
+             */
+            if ( detect_transition_to_still( cpi, i,
+                                             (cpi->key_frame_frequency-i),
+                                             loop_decay_rate,
+                                             decay_accumulator ) )
+            {
+                break;
+            }
+
+
+            /* Step on to the next frame */
+            cpi->twopass.frames_to_key ++;
+
+            /* If we don't have a real key frame within the next two
+             * forcekeyframeevery intervals then break out of the loop.
+             */
+            if (cpi->twopass.frames_to_key >= 2 *(int)cpi->key_frame_frequency)
+                break;
+        } else
+            cpi->twopass.frames_to_key ++;
+
+        i++;
+    }
+
+    /* If there is a max kf interval set by the user we must obey it.
+     * We already breakout of the loop above at 2x max.
+     * This code centers the extra kf if the actual natural
+     * interval is between 1x and 2x
+     */
+    if (cpi->oxcf.auto_key
+        && cpi->twopass.frames_to_key > (int)cpi->key_frame_frequency )
+    {
+        FIRSTPASS_STATS *current_pos = cpi->twopass.stats_in;
+        FIRSTPASS_STATS tmp_frame;
+
+        cpi->twopass.frames_to_key /= 2;
+
+        /* Copy first frame details */
+        memcpy(&tmp_frame, &first_frame, sizeof(first_frame));
+
+        /* Reset to the start of the group */
+        reset_fpf_position(cpi, start_position);
+
+        kf_group_err = 0;
+        kf_group_intra_err = 0;
+        kf_group_coded_err = 0;
+
+        /* Rescan to get the correct error data for the forced kf group */
+        for( i = 0; i < cpi->twopass.frames_to_key; i++ )
+        {
+            /* Accumulate kf group errors */
+            kf_group_err += calculate_modified_err(cpi, &tmp_frame);
+            kf_group_intra_err += tmp_frame.intra_error;
+            kf_group_coded_err += tmp_frame.coded_error;
+
+            /* Load a the next frame's stats */
+            input_stats(cpi, &tmp_frame);
+        }
+
+        /* Reset to the start of the group */
+        reset_fpf_position(cpi, current_pos);
+
+        cpi->next_key_frame_forced = 1;
+    }
+    else
+        cpi->next_key_frame_forced = 0;
+
+    /* Special case for the last frame of the file */
+    if (cpi->twopass.stats_in >= cpi->twopass.stats_in_end)
+    {
+        /* Accumulate kf group error */
+        kf_group_err += calculate_modified_err(cpi, this_frame);
+
+        /* These figures keep intra and coded error counts for all frames
+         * including key frames in the group. The effect of the key frame
+         * itself can be subtracted out using the first_frame data
+         * collected above
+         */
+        kf_group_intra_err += this_frame->intra_error;
+        kf_group_coded_err += this_frame->coded_error;
+    }
+
+    /* Calculate the number of bits that should be assigned to the kf group. */
+    if ((cpi->twopass.bits_left > 0) && (cpi->twopass.modified_error_left > 0.0))
+    {
+        /* Max for a single normal frame (not key frame) */
+        int max_bits = frame_max_bits(cpi);
+
+        /* Maximum bits for the kf group */
+        int64_t max_grp_bits;
+
+        /* Default allocation based on bits left and relative
+         * complexity of the section
+         */
+        cpi->twopass.kf_group_bits = (int64_t)( cpi->twopass.bits_left *
+                                          ( kf_group_err /
+                                            cpi->twopass.modified_error_left ));
+
+        /* Clip based on maximum per frame rate defined by the user. */
+        max_grp_bits = (int64_t)max_bits * (int64_t)cpi->twopass.frames_to_key;
+        if (cpi->twopass.kf_group_bits > max_grp_bits)
+            cpi->twopass.kf_group_bits = max_grp_bits;
+
+        /* Additional special case for CBR if buffer is getting full. */
+        if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+        {
+            int64_t opt_buffer_lvl = cpi->oxcf.optimal_buffer_level;
+            int64_t buffer_lvl = cpi->buffer_level;
+
+            /* If the buffer is near or above the optimal and this kf group is
+             * not being allocated much then increase the allocation a bit.
+             */
+            if (buffer_lvl >= opt_buffer_lvl)
+            {
+                int64_t high_water_mark = (opt_buffer_lvl +
+                                       cpi->oxcf.maximum_buffer_size) >> 1;
+
+                int64_t av_group_bits;
+
+                /* Av bits per frame * number of frames */
+                av_group_bits = (int64_t)cpi->av_per_frame_bandwidth *
+                                (int64_t)cpi->twopass.frames_to_key;
+
+                /* We are at or above the maximum. */
+                if (cpi->buffer_level >= high_water_mark)
+                {
+                    int64_t min_group_bits;
+
+                    min_group_bits = av_group_bits +
+                                     (int64_t)(buffer_lvl -
+                                                 high_water_mark);
+
+                    if (cpi->twopass.kf_group_bits < min_group_bits)
+                        cpi->twopass.kf_group_bits = min_group_bits;
+                }
+                /* We are above optimal but below the maximum */
+                else if (cpi->twopass.kf_group_bits < av_group_bits)
+                {
+                    int64_t bits_below_av = av_group_bits -
+                                              cpi->twopass.kf_group_bits;
+
+                    cpi->twopass.kf_group_bits +=
+                       (int64_t)((double)bits_below_av *
+                                   (double)(buffer_lvl - opt_buffer_lvl) /
+                                   (double)(high_water_mark - opt_buffer_lvl));
+                }
+            }
+        }
+    }
+    else
+        cpi->twopass.kf_group_bits = 0;
+
+    /* Reset the first pass file position */
+    reset_fpf_position(cpi, start_position);
+
+    /* determine how big to make this keyframe based on how well the
+     * subsequent frames use inter blocks
+     */
+    decay_accumulator = 1.0;
+    boost_score = 0.0;
+
+    for (i = 0 ; i < cpi->twopass.frames_to_key ; i++)
+    {
+        double r;
+
+        if (EOF == input_stats(cpi, &next_frame))
+            break;
+
+        if (next_frame.intra_error > cpi->twopass.kf_intra_err_min)
+            r = (IIKFACTOR2 * next_frame.intra_error /
+                     DOUBLE_DIVIDE_CHECK(next_frame.coded_error));
+        else
+            r = (IIKFACTOR2 * cpi->twopass.kf_intra_err_min /
+                     DOUBLE_DIVIDE_CHECK(next_frame.coded_error));
+
+        if (r > RMAX)
+            r = RMAX;
+
+        /* How fast is prediction quality decaying */
+        loop_decay_rate = get_prediction_decay_rate(cpi, &next_frame);
+
+        decay_accumulator = decay_accumulator * loop_decay_rate;
+        decay_accumulator = decay_accumulator < 0.1 ? 0.1 : decay_accumulator;
+
+        boost_score += (decay_accumulator * r);
+
+        if ((i > MIN_GF_INTERVAL) &&
+            ((boost_score - old_boost_score) < 1.0))
+        {
+            break;
+        }
+
+        old_boost_score = boost_score;
+    }
+
+    if (1)
+    {
+        FIRSTPASS_STATS sectionstats;
+        double Ratio;
+
+        zero_stats(&sectionstats);
+        reset_fpf_position(cpi, start_position);
+
+        for (i = 0 ; i < cpi->twopass.frames_to_key ; i++)
+        {
+            input_stats(cpi, &next_frame);
+            accumulate_stats(&sectionstats, &next_frame);
+        }
+
+        avg_stats(&sectionstats);
+
+        cpi->twopass.section_intra_rating = (unsigned int)
+            (sectionstats.intra_error
+            / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error));
+
+        Ratio = sectionstats.intra_error / DOUBLE_DIVIDE_CHECK(sectionstats.coded_error);
+        cpi->twopass.section_max_qfactor = 1.0 - ((Ratio - 10.0) * 0.025);
+
+        if (cpi->twopass.section_max_qfactor < 0.80)
+            cpi->twopass.section_max_qfactor = 0.80;
+    }
+
+    /* When using CBR apply additional buffer fullness related upper limits */
+    if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+    {
+        double max_boost;
+
+        if (cpi->drop_frames_allowed)
+        {
+            int df_buffer_level = (int)(cpi->oxcf.drop_frames_water_mark
+                                  * (cpi->oxcf.optimal_buffer_level / 100));
+
+            if (cpi->buffer_level > df_buffer_level)
+                max_boost = ((double)((cpi->buffer_level - df_buffer_level) * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
+            else
+                max_boost = 0.0;
+        }
+        else if (cpi->buffer_level > 0)
+        {
+            max_boost = ((double)(cpi->buffer_level * 2 / 3) * 16.0) / DOUBLE_DIVIDE_CHECK((double)cpi->av_per_frame_bandwidth);
+        }
+        else
+        {
+            max_boost = 0.0;
+        }
+
+        if (boost_score > max_boost)
+            boost_score = max_boost;
+    }
+
+    /* Reset the first pass file position */
+    reset_fpf_position(cpi, start_position);
+
+    /* Work out how many bits to allocate for the key frame itself */
+    if (1)
+    {
+        int kf_boost = (int)boost_score;
+        int allocation_chunks;
+        int Counter = cpi->twopass.frames_to_key;
+        int alt_kf_bits;
+        YV12_BUFFER_CONFIG *lst_yv12 = &cpi->common.yv12_fb[cpi->common.lst_fb_idx];
+        /* Min boost based on kf interval */
+#if 0
+
+        while ((kf_boost < 48) && (Counter > 0))
+        {
+            Counter -= 2;
+            kf_boost ++;
+        }
+
+#endif
+
+        if (kf_boost < 48)
+        {
+            kf_boost += ((Counter + 1) >> 1);
+
+            if (kf_boost > 48) kf_boost = 48;
+        }
+
+        /* bigger frame sizes need larger kf boosts, smaller frames smaller
+         * boosts...
+         */
+        if ((lst_yv12->y_width * lst_yv12->y_height) > (320 * 240))
+            kf_boost += 2 * (lst_yv12->y_width * lst_yv12->y_height) / (320 * 240);
+        else if ((lst_yv12->y_width * lst_yv12->y_height) < (320 * 240))
+            kf_boost -= 4 * (320 * 240) / (lst_yv12->y_width * lst_yv12->y_height);
+
+        /* Min KF boost */
+        kf_boost = (int)((double)kf_boost * 100.0) >> 4; /* Scale 16 to 100 */
+        if (kf_boost < 250)
+            kf_boost = 250;
+
+        /*
+         * We do three calculations for kf size.
+         * The first is based on the error score for the whole kf group.
+         * The second (optionaly) on the key frames own error if this is
+         * smaller than the average for the group.
+         * The final one insures that the frame receives at least the
+         * allocation it would have received based on its own error score vs
+         * the error score remaining
+         * Special case if the sequence appears almost totaly static
+         * as measured by the decay accumulator. In this case we want to
+         * spend almost all of the bits on the key frame.
+         * cpi->twopass.frames_to_key-1 because key frame itself is taken
+         * care of by kf_boost.
+         */
+        if ( decay_accumulator >= 0.99 )
+        {
+            allocation_chunks =
+                ((cpi->twopass.frames_to_key - 1) * 10) + kf_boost;
+        }
+        else
+        {
+            allocation_chunks =
+                ((cpi->twopass.frames_to_key - 1) * 100) + kf_boost;
+        }
+
+        /* Normalize Altboost and allocations chunck down to prevent overflow */
+        while (kf_boost > 1000)
+        {
+            kf_boost /= 2;
+            allocation_chunks /= 2;
+        }
+
+        cpi->twopass.kf_group_bits = (cpi->twopass.kf_group_bits < 0) ? 0 : cpi->twopass.kf_group_bits;
+
+        /* Calculate the number of bits to be spent on the key frame */
+        cpi->twopass.kf_bits  = (int)((double)kf_boost * ((double)cpi->twopass.kf_group_bits / (double)allocation_chunks));
+
+        /* Apply an additional limit for CBR */
+        if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+        {
+            if (cpi->twopass.kf_bits > (int)((3 * cpi->buffer_level) >> 2))
+                cpi->twopass.kf_bits = (int)((3 * cpi->buffer_level) >> 2);
+        }
+
+        /* If the key frame is actually easier than the average for the
+         * kf group (which does sometimes happen... eg a blank intro frame)
+         * Then use an alternate calculation based on the kf error score
+         * which should give a smaller key frame.
+         */
+        if (kf_mod_err < kf_group_err / cpi->twopass.frames_to_key)
+        {
+            double  alt_kf_grp_bits =
+                        ((double)cpi->twopass.bits_left *
+                         (kf_mod_err * (double)cpi->twopass.frames_to_key) /
+                         DOUBLE_DIVIDE_CHECK(cpi->twopass.modified_error_left));
+
+            alt_kf_bits = (int)((double)kf_boost *
+                                (alt_kf_grp_bits / (double)allocation_chunks));
+
+            if (cpi->twopass.kf_bits > alt_kf_bits)
+            {
+                cpi->twopass.kf_bits = alt_kf_bits;
+            }
+        }
+        /* Else if it is much harder than other frames in the group make sure
+         * it at least receives an allocation in keeping with its relative
+         * error score
+         */
+        else
+        {
+            alt_kf_bits =
+                (int)((double)cpi->twopass.bits_left *
+                      (kf_mod_err /
+                       DOUBLE_DIVIDE_CHECK(cpi->twopass.modified_error_left)));
+
+            if (alt_kf_bits > cpi->twopass.kf_bits)
+            {
+                cpi->twopass.kf_bits = alt_kf_bits;
+            }
+        }
+
+        cpi->twopass.kf_group_bits -= cpi->twopass.kf_bits;
+        /* Add in the minimum frame allowance */
+        cpi->twopass.kf_bits += cpi->min_frame_bandwidth;
+
+        /* Peer frame bit target for this frame */
+        cpi->per_frame_bandwidth = cpi->twopass.kf_bits;
+
+        /* Convert to a per second bitrate */
+        cpi->target_bandwidth = (int)(cpi->twopass.kf_bits *
+                                      cpi->output_framerate);
+    }
+
+    /* Note the total error score of the kf group minus the key frame itself */
+    cpi->twopass.kf_group_error_left = (int)(kf_group_err - kf_mod_err);
+
+    /* Adjust the count of total modified error left. The count of bits left
+     * is adjusted elsewhere based on real coded frame sizes
+     */
+    cpi->twopass.modified_error_left -= kf_group_err;
+
+    if (cpi->oxcf.allow_spatial_resampling)
+    {
+        int resample_trigger = 0;
+        int last_kf_resampled = 0;
+        int kf_q;
+        int scale_val = 0;
+        int hr, hs, vr, vs;
+        int new_width = cpi->oxcf.Width;
+        int new_height = cpi->oxcf.Height;
+
+        int projected_buffer_level;
+        int tmp_q;
+
+        double projected_bits_perframe;
+        double group_iiratio = (kf_group_intra_err - first_frame.intra_error) / (kf_group_coded_err - first_frame.coded_error);
+        double err_per_frame = kf_group_err / cpi->twopass.frames_to_key;
+        double bits_per_frame;
+        double av_bits_per_frame;
+        double effective_size_ratio;
+
+        if ((cpi->common.Width != cpi->oxcf.Width) || (cpi->common.Height != cpi->oxcf.Height))
+            last_kf_resampled = 1;
+
+        /* Set back to unscaled by defaults */
+        cpi->common.horiz_scale = NORMAL;
+        cpi->common.vert_scale = NORMAL;
+
+        /* Calculate Average bits per frame. */
+        av_bits_per_frame = cpi->oxcf.target_bandwidth / DOUBLE_DIVIDE_CHECK((double)cpi->framerate);
+
+        /* CBR... Use the clip average as the target for deciding resample */
+        if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+        {
+            bits_per_frame = av_bits_per_frame;
+        }
+
+        /* In VBR we want to avoid downsampling in easy section unless we
+         * are under extreme pressure So use the larger of target bitrate
+         * for this section or average bitrate for sequence
+         */
+        else
+        {
+            /* This accounts for how hard the section is... */
+            bits_per_frame = (double)
+                (cpi->twopass.kf_group_bits / cpi->twopass.frames_to_key);
+
+            /* Dont turn to resampling in easy sections just because they
+             * have been assigned a small number of bits
+             */
+            if (bits_per_frame < av_bits_per_frame)
+                bits_per_frame = av_bits_per_frame;
+        }
+
+        /* bits_per_frame should comply with our minimum */
+        if (bits_per_frame < (cpi->oxcf.target_bandwidth * cpi->oxcf.two_pass_vbrmin_section / 100))
+            bits_per_frame = (cpi->oxcf.target_bandwidth * cpi->oxcf.two_pass_vbrmin_section / 100);
+
+        /* Work out if spatial resampling is necessary */
+        kf_q = estimate_kf_group_q(cpi, err_per_frame,
+                                  (int)bits_per_frame, group_iiratio);
+
+        /* If we project a required Q higher than the maximum allowed Q then
+         * make a guess at the actual size of frames in this section
+         */
+        projected_bits_perframe = bits_per_frame;
+        tmp_q = kf_q;
+
+        while (tmp_q > cpi->worst_quality)
+        {
+            projected_bits_perframe *= 1.04;
+            tmp_q--;
+        }
+
+        /* Guess at buffer level at the end of the section */
+        projected_buffer_level = (int)
+                    (cpi->buffer_level - (int)
+                    ((projected_bits_perframe - av_bits_per_frame) *
+                    cpi->twopass.frames_to_key));
+
+        if (0)
+        {
+            FILE *f = fopen("Subsamle.stt", "a");
+            fprintf(f, " %8d %8d %8d %8d %12.0f %8d %8d %8d\n",  cpi->common.current_video_frame, kf_q, cpi->common.horiz_scale, cpi->common.vert_scale,  kf_group_err / cpi->twopass.frames_to_key, (int)(cpi->twopass.kf_group_bits / cpi->twopass.frames_to_key), new_height, new_width);
+            fclose(f);
+        }
+
+        /* The trigger for spatial resampling depends on the various
+         * parameters such as whether we are streaming (CBR) or VBR.
+         */
+        if (cpi->oxcf.end_usage == USAGE_STREAM_FROM_SERVER)
+        {
+            /* Trigger resample if we are projected to fall below down
+             * sample level or resampled last time and are projected to
+             * remain below the up sample level
+             */
+            if ((projected_buffer_level < (cpi->oxcf.resample_down_water_mark * cpi->oxcf.optimal_buffer_level / 100)) ||
+                (last_kf_resampled && (projected_buffer_level < (cpi->oxcf.resample_up_water_mark * cpi->oxcf.optimal_buffer_level / 100))))
+                resample_trigger = 1;
+            else
+                resample_trigger = 0;
+        }
+        else
+        {
+            int64_t clip_bits = (int64_t)(cpi->twopass.total_stats.count * cpi->oxcf.target_bandwidth / DOUBLE_DIVIDE_CHECK((double)cpi->framerate));
+            int64_t over_spend = cpi->oxcf.starting_buffer_level - cpi->buffer_level;
+
+            /* If triggered last time the threshold for triggering again is
+             * reduced:
+             *
+             * Projected Q higher than allowed and Overspend > 5% of total
+             * bits
+             */
+            if ((last_kf_resampled && (kf_q > cpi->worst_quality)) ||
+                ((kf_q > cpi->worst_quality) &&
+                 (over_spend > clip_bits / 20)))
+                resample_trigger = 1;
+            else
+                resample_trigger = 0;
+
+        }
+
+        if (resample_trigger)
+        {
+            while ((kf_q >= cpi->worst_quality) && (scale_val < 6))
+            {
+                scale_val ++;
+
+                cpi->common.vert_scale   = vscale_lookup[scale_val];
+                cpi->common.horiz_scale  = hscale_lookup[scale_val];
+
+                Scale2Ratio(cpi->common.horiz_scale, &hr, &hs);
+                Scale2Ratio(cpi->common.vert_scale, &vr, &vs);
+
+                new_width = ((hs - 1) + (cpi->oxcf.Width * hr)) / hs;
+                new_height = ((vs - 1) + (cpi->oxcf.Height * vr)) / vs;
+
+                /* Reducing the area to 1/4 does not reduce the complexity
+                 * (err_per_frame) to 1/4... effective_sizeratio attempts
+                 * to provide a crude correction for this
+                 */
+                effective_size_ratio = (double)(new_width * new_height) / (double)(cpi->oxcf.Width * cpi->oxcf.Height);
+                effective_size_ratio = (1.0 + (3.0 * effective_size_ratio)) / 4.0;
+
+                /* Now try again and see what Q we get with the smaller
+                 * image size
+                 */
+                kf_q = estimate_kf_group_q(cpi,
+                                          err_per_frame * effective_size_ratio,
+                                          (int)bits_per_frame, group_iiratio);
+
+                if (0)
+                {
+                    FILE *f = fopen("Subsamle.stt", "a");
+                    fprintf(f, "******** %8d %8d %8d %12.0f %8d %8d %8d\n",  kf_q, cpi->common.horiz_scale, cpi->common.vert_scale,  kf_group_err / cpi->twopass.frames_to_key, (int)(cpi->twopass.kf_group_bits / cpi->twopass.frames_to_key), new_height, new_width);
+                    fclose(f);
+                }
+            }
+        }
+
+        if ((cpi->common.Width != new_width) || (cpi->common.Height != new_height))
+        {
+            cpi->common.Width = new_width;
+            cpi->common.Height = new_height;
+            vp8_alloc_compressor_data(cpi);
+        }
+    }
+}