diff -r 000000000000 -r 6474c204b198 media/libvpx/vp9/encoder/vp9_psnr.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/media/libvpx/vp9/encoder/vp9_psnr.c	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,29 @@
+/*
+ *  Copyright (c) 2010 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 "vpx_scale/yv12config.h"
+
+#define MAX_PSNR 100
+
+double vp9_mse2psnr(double samples, double peak, double mse) {
+  double psnr;
+
+  if (mse > 0.0)
+    psnr = 10.0 * log10(peak * peak * samples / mse);
+  else
+    psnr = MAX_PSNR;  // Limit to prevent / 0
+
+  if (psnr > MAX_PSNR)
+    psnr = MAX_PSNR;
+
+  return psnr;
+}