1 files changed, 74 insertions, 0 deletions
diff --git a/media/libvpx/libvpx/vpx_dsp/add_noise.c b/media/libvpx/libvpx/vpx_dsp/add_noise.c
new file mode 100644
index 0000000000..6839e97928
--- /dev/null
+++ b/media/libvpx/libvpx/vpx_dsp/add_noise.c
@@ -0,0 +1,74 @@
+/*
+ *  Copyright (c) 2015 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 <stdlib.h>
+
+#include "./vpx_config.h"
+#include "./vpx_dsp_rtcd.h"
+
+#include "vpx/vpx_integer.h"
+#include "vpx_dsp/postproc.h"
+#include "vpx_ports/mem.h"
+
+void vpx_plane_add_noise_c(uint8_t *start, const int8_t *noise, int blackclamp,
+                           int whiteclamp, int width, int height, int pitch) {
+  int i, j;
+  int bothclamp = blackclamp + whiteclamp;
+  for (i = 0; i < height; ++i) {
+    uint8_t *pos = start + i * pitch;
+    const int8_t *ref = (const int8_t *)(noise + (rand() & 0xff));  // NOLINT
+
+    for (j = 0; j < width; ++j) {
+      int v = pos[j];
+
+      v = clamp(v - blackclamp, 0, 255);
+      v = clamp(v + bothclamp, 0, 255);
+      v = clamp(v - whiteclamp, 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 vpx_setup_noise(double sigma, int8_t *noise, int size) {
+  int8_t 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) {
+        if (next + j >= 256) goto set_noise;
+        char_dist[next + j] = (int8_t)i;
+      }
+      next = next + j;
+    }
+  }
+
+  // Rounding error - might mean we have less than 256.
+  for (; next < 256; ++next) {
+    char_dist[next] = 0;
+  }
+
+set_noise:
+  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];
+}