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-rw-r--r--third_party/aom/av1/encoder/laplace_encoder.c107
1 files changed, 107 insertions, 0 deletions
diff --git a/third_party/aom/av1/encoder/laplace_encoder.c b/third_party/aom/av1/encoder/laplace_encoder.c
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+/*
+ * Copyright (c) 2001-2016, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+/* clang-format off */
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stdio.h>
+
+#include "aom_dsp/bitwriter.h"
+#include "av1/common/odintrin.h"
+#include "av1/common/pvq.h"
+#include "pvq_encoder.h"
+
+static void aom_encode_pvq_split(aom_writer *w, od_pvq_codeword_ctx *adapt,
+ int count, int sum, int ctx) {
+ int shift;
+ int rest;
+ int fctx;
+ if (sum == 0) return;
+ shift = OD_MAXI(0, OD_ILOG(sum) - 3);
+ if (shift) {
+ rest = count & ((1 << shift) - 1);
+ count >>= shift;
+ sum >>= shift;
+ }
+ fctx = 7*ctx + sum - 1;
+ aom_write_symbol_pvq(w, count, adapt->pvq_split_cdf[fctx], sum + 1);
+ if (shift) aom_write_literal(w, rest, shift);
+}
+
+void aom_encode_band_pvq_splits(aom_writer *w, od_pvq_codeword_ctx *adapt,
+ const int *y, int n, int k, int level) {
+ int mid;
+ int i;
+ int count_right;
+ if (n <= 1 || k == 0) return;
+ if (k == 1 && n <= 16) {
+ int cdf_id;
+ int pos;
+ cdf_id = od_pvq_k1_ctx(n, level == 0);
+ for (pos = 0; !y[pos]; pos++);
+ OD_ASSERT(pos < n);
+ aom_write_symbol_pvq(w, pos, adapt->pvq_k1_cdf[cdf_id], n);
+ }
+ else {
+ mid = n >> 1;
+ count_right = k;
+ for (i = 0; i < mid; i++) count_right -= abs(y[i]);
+ aom_encode_pvq_split(w, adapt, count_right, k, od_pvq_size_ctx(n));
+ aom_encode_band_pvq_splits(w, adapt, y, mid, k - count_right, level + 1);
+ aom_encode_band_pvq_splits(w, adapt, y + mid, n - mid, count_right,
+ level + 1);
+ }
+}
+
+/** Encodes the tail of a Laplace-distributed variable, i.e. it doesn't
+ * do anything special for the zero case.
+ *
+ * @param [in,out] enc range encoder
+ * @param [in] x variable to encode (has to be positive)
+ * @param [in] decay decay factor of the distribution in Q8 format,
+ * i.e. pdf ~= decay^x
+ */
+void aom_laplace_encode_special(aom_writer *w, int x, unsigned decay) {
+ int shift;
+ int xs;
+ int sym;
+ const uint16_t *cdf;
+ shift = 0;
+ /* We don't want a large decay value because that would require too many
+ symbols. */
+ while (decay > 235) {
+ decay = (decay*decay + 128) >> 8;
+ shift++;
+ }
+ decay = OD_MINI(decay, 254);
+ decay = OD_MAXI(decay, 2);
+ xs = x >> shift;
+ cdf = EXP_CDF_TABLE[(decay + 1) >> 1];
+ OD_LOG((OD_LOG_PVQ, OD_LOG_DEBUG, "decay = %d", decay));
+ do {
+ sym = OD_MINI(xs, 15);
+ {
+ int i;
+ OD_LOG((OD_LOG_PVQ, OD_LOG_DEBUG, "%d %d %d %d %d\n", x, xs, shift,
+ sym, max));
+ for (i = 0; i < 16; i++) {
+ OD_LOG_PARTIAL((OD_LOG_PVQ, OD_LOG_DEBUG, "%d ", cdf[i]));
+ }
+ OD_LOG_PARTIAL((OD_LOG_PVQ, OD_LOG_DEBUG, "\n"));
+ }
+ aom_write_cdf(w, sym, cdf, 16);
+ xs -= 15;
+ } while (sym >= 15);
+ if (shift) aom_write_literal(w, x & ((1 << shift) - 1), shift);
+}