diff options
Diffstat (limited to 'media/libvpx/vp9/encoder/vp9_blockiness.c')
| -rw-r--r-- | media/libvpx/vp9/encoder/vp9_blockiness.c | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/media/libvpx/vp9/encoder/vp9_blockiness.c b/media/libvpx/vp9/encoder/vp9_blockiness.c new file mode 100644 index 000000000..b8629bd3b --- /dev/null +++ b/media/libvpx/vp9/encoder/vp9_blockiness.c @@ -0,0 +1,138 @@ +/* + * Copyright (c) 2014 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 "./vpx_config.h" +#include "./vp9_rtcd.h" +#include "vp9/common/vp9_common.h" +#include "vp9/common/vp9_convolve.h" +#include "vp9/common/vp9_filter.h" +#include "vpx/vpx_integer.h" +#include "vpx_ports/mem.h" + +static int horizontal_filter(const uint8_t *s) { + return (s[1] - s[-2]) * 2 + (s[-1] - s[0]) * 6; +} + +static int vertical_filter(const uint8_t *s, int p) { + return (s[p] - s[-2 * p]) * 2 + (s[-p] - s[0]) * 6; +} + +static int variance(int sum, int sum_squared, int size) { + return sum_squared / size - (sum / size) * (sum / size); +} +// Calculate a blockiness level for a vertical block edge. +// This function returns a new blockiness metric that's defined as + +// p0 p1 p2 p3 +// q0 q1 q2 q3 +// block edge -> +// r0 r1 r2 r3 +// s0 s1 s2 s3 + +// blockiness = p0*-2+q0*6+r0*-6+s0*2 + +// p1*-2+q1*6+r1*-6+s1*2 + +// p2*-2+q2*6+r2*-6+s2*2 + +// p3*-2+q3*6+r3*-6+s3*2 ; + +// reconstructed_blockiness = abs(blockiness from reconstructed buffer - +// blockiness from source buffer,0) +// +// I make the assumption that flat blocks are much more visible than high +// contrast blocks. As such, I scale the result of the blockiness calc +// by dividing the blockiness by the variance of the pixels on either side +// of the edge as follows: +// var_0 = (q0^2+q1^2+q2^2+q3^2) - ((q0 + q1 + q2 + q3) / 4 )^2 +// var_1 = (r0^2+r1^2+r2^2+r3^2) - ((r0 + r1 + r2 + r3) / 4 )^2 +// The returned blockiness is the scaled value +// Reconstructed blockiness / ( 1 + var_0 + var_1 ) ; +int blockiness_vertical(const uint8_t *s, int sp, const uint8_t *r, int rp, + int size) { + int s_blockiness = 0; + int r_blockiness = 0; + int sum_0 = 0; + int sum_sq_0 = 0; + int sum_1 = 0; + int sum_sq_1 = 0; + int i; + int var_0; + int var_1; + for (i = 0; i < size; ++i, s += sp, r += rp) { + s_blockiness += horizontal_filter(s); + r_blockiness += horizontal_filter(r); + sum_0 += s[0]; + sum_sq_0 += s[0]*s[0]; + sum_1 += s[-1]; + sum_sq_1 += s[-1]*s[-1]; + } + var_0 = variance(sum_0, sum_sq_0, size); + var_1 = variance(sum_1, sum_sq_1, size); + r_blockiness = abs(r_blockiness); + s_blockiness = abs(s_blockiness); + + if (r_blockiness > s_blockiness) + return (r_blockiness - s_blockiness) / (1 + var_0 + var_1); + else + return 0; +} + +// Calculate a blockiness level for a horizontal block edge +// same as above. +int blockiness_horizontal(const uint8_t *s, int sp, const uint8_t *r, int rp, + int size) { + int s_blockiness = 0; + int r_blockiness = 0; + int sum_0 = 0; + int sum_sq_0 = 0; + int sum_1 = 0; + int sum_sq_1 = 0; + int i; + int var_0; + int var_1; + for (i = 0; i < size; ++i, ++s, ++r) { + s_blockiness += vertical_filter(s, sp); + r_blockiness += vertical_filter(r, rp); + sum_0 += s[0]; + sum_sq_0 += s[0] * s[0]; + sum_1 += s[-sp]; + sum_sq_1 += s[-sp] * s[-sp]; + } + var_0 = variance(sum_0, sum_sq_0, size); + var_1 = variance(sum_1, sum_sq_1, size); + r_blockiness = abs(r_blockiness); + s_blockiness = abs(s_blockiness); + + if (r_blockiness > s_blockiness) + return (r_blockiness - s_blockiness) / (1 + var_0 + var_1); + else + return 0; +} + +// This function returns the blockiness for the entire frame currently by +// looking at all borders in steps of 4. +double vp9_get_blockiness(const unsigned char *img1, int img1_pitch, + const unsigned char *img2, int img2_pitch, + int width, int height ) { + double blockiness = 0; + int i, j; + vp9_clear_system_state(); + for (i = 0; i < height; i += 4, img1 += img1_pitch * 4, + img2 += img2_pitch * 4) { + for (j = 0; j < width; j += 4) { + if (i > 0 && i < height && j > 0 && j < width) { + blockiness += blockiness_vertical(img1 + j, img1_pitch, + img2 + j, img2_pitch, 4); + blockiness += blockiness_horizontal(img1 + j, img1_pitch, + img2 + j, img2_pitch, 4); + } + } + } + blockiness /= width * height / 16; + return blockiness; +} |