Import aom library

This is the reference implementation for the Alliance for Open Media's av1 video code.

The commit used was 4d668d7feb1f8abd809d1bca0418570a7f142a36.

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
new file mode 100644
index 000000000..54ffc88fb
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+++ b/third_party/aom/av1/encoder/laplace_encoder.c
@@ -0,0 +1,107 @@
+/*
+ * 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);
+}