Import aom library

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

The commit used was 4d668d7feb1f8abd809d1bca0418570a7f142a36.

third_party/aom/aom_dsp/add_noise.c

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 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.
+ */
+
+#include <math.h>
+#include <stdlib.h>
+
+#include "./aom_config.h"
+#include "./aom_dsp_rtcd.h"
+
+#include "aom/aom_integer.h"
+#include "aom_ports/mem.h"
+
+void aom_plane_add_noise_c(uint8_t *start, char *noise, char blackclamp[16],
+                           char whiteclamp[16], char bothclamp[16],
+                           unsigned int width, unsigned int height, int pitch) {
+  unsigned int i, j;
+
+  for (i = 0; i < height; ++i) {
+    uint8_t *pos = start + i * pitch;
+    char *ref = (char *)(noise + (rand() & 0xff));  // NOLINT
+
+    for (j = 0; j < width; ++j) {
+      int v = pos[j];
+
+      v = clamp(v - blackclamp[0], 0, 255);
+      v = clamp(v + bothclamp[0], 0, 255);
+      v = clamp(v - whiteclamp[0], 0, 255);
+
+      pos[j] = v + ref[j];
+    }
+  }
+}
+
+static double gaussian(double sigma, double mu, double x) {
+  return 1 / (sigma * sqrt(2.0 * 3.14159265)) *
+         (exp(-(x - mu) * (x - mu) / (2 * sigma * sigma)));
+}
+
+int aom_setup_noise(double sigma, int size, char *noise) {
+  char char_dist[256];
+  int next = 0, i, j;
+
+  // set up a 256 entry lookup that matches gaussian distribution
+  for (i = -32; i < 32; ++i) {
+    const int a_i = (int)(0.5 + 256 * gaussian(sigma, 0, i));
+    if (a_i) {
+      for (j = 0; j < a_i; ++j) {
+        char_dist[next + j] = (char)i;
+      }
+      next = next + j;
+    }
+  }
+
+  // Rounding error - might mean we have less than 256.
+  for (; next < 256; ++next) {
+    char_dist[next] = 0;
+  }
+
+  for (i = 0; i < size; ++i) {
+    noise[i] = char_dist[rand() & 0xff];  // NOLINT
+  }
+
+  // Returns the highest non 0 value used in distribution.
+  return -char_dist[0];
+}