diff -r 000000000000 -r 6474c204b198 content/media/compiledtest/TestAudioMixer.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/compiledtest/TestAudioMixer.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,156 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "AudioMixer.h"
+#include <assert.h>
+
+using mozilla::AudioDataValue;
+using mozilla::AudioSampleFormat;
+
+/* In this test, the different audio stream and channels are always created to
+ * cancel each other. */
+void MixingDone(AudioDataValue* aData, AudioSampleFormat aFormat, uint32_t aChannels, uint32_t aFrames, uint32_t aSampleRate)
+{
+  bool silent = true;
+  for (uint32_t i = 0; i < aChannels * aFrames; i++) {
+    if (aData[i] != 0.0) {
+      if (aFormat == mozilla::AUDIO_FORMAT_S16) {
+        fprintf(stderr, "Sample at %d is not silent: %d\n", i, (short)aData[i]);
+      } else {
+        fprintf(stderr, "Sample at %d is not silent: %f\n", i, (float)aData[i]);
+      }
+      silent = false;
+    }
+  }
+  if (!silent) {
+    MOZ_CRASH();
+  }
+}
+
+/* Helper function to give us the maximum and minimum value that don't clip,
+ * for a given sample format (integer or floating-point). */
+template<typename T>
+T GetLowValue();
+
+template<typename T>
+T GetHighValue();
+
+template<>
+float GetLowValue<float>() {
+  return -1.0;
+}
+
+template<>
+short GetLowValue<short>() {
+  return -INT16_MAX;
+}
+
+template<>
+float GetHighValue<float>() {
+  return 1.0;
+}
+
+template<>
+short GetHighValue<short>() {
+  return INT16_MAX;
+}
+
+void FillBuffer(AudioDataValue* aBuffer, uint32_t aLength, AudioDataValue aValue)
+{
+  AudioDataValue* end = aBuffer + aLength;
+  while (aBuffer != end) {
+    *aBuffer++ = aValue;
+  }
+}
+
+int main(int argc, char* argv[]) {
+  const uint32_t CHANNEL_LENGTH = 256;
+  const uint32_t AUDIO_RATE = 44100;
+  AudioDataValue a[CHANNEL_LENGTH * 2];
+  AudioDataValue b[CHANNEL_LENGTH * 2];
+  FillBuffer(a, CHANNEL_LENGTH, GetLowValue<AudioDataValue>());
+  FillBuffer(a + CHANNEL_LENGTH, CHANNEL_LENGTH, GetHighValue<AudioDataValue>());
+  FillBuffer(b, CHANNEL_LENGTH, GetHighValue<AudioDataValue>());
+  FillBuffer(b + CHANNEL_LENGTH, CHANNEL_LENGTH, GetLowValue<AudioDataValue>());
+
+  {
+    int iterations = 2;
+    mozilla::AudioMixer mixer(MixingDone);
+
+    fprintf(stderr, "Test AudioMixer constant buffer length.\n");
+
+    while (iterations--) {
+      mixer.Mix(a, 2, CHANNEL_LENGTH, AUDIO_RATE);
+      mixer.Mix(b, 2, CHANNEL_LENGTH, AUDIO_RATE);
+      mixer.FinishMixing();
+    }
+  }
+
+  {
+    mozilla::AudioMixer mixer(MixingDone);
+
+    fprintf(stderr, "Test AudioMixer variable buffer length.\n");
+
+    FillBuffer(a, CHANNEL_LENGTH / 2, GetLowValue<AudioDataValue>());
+    FillBuffer(a + CHANNEL_LENGTH / 2, CHANNEL_LENGTH / 2, GetLowValue<AudioDataValue>());
+    FillBuffer(b, CHANNEL_LENGTH / 2, GetHighValue<AudioDataValue>());
+    FillBuffer(b + CHANNEL_LENGTH / 2, CHANNEL_LENGTH / 2, GetHighValue<AudioDataValue>());
+    mixer.Mix(a, 2, CHANNEL_LENGTH / 2, AUDIO_RATE);
+    mixer.Mix(b, 2, CHANNEL_LENGTH / 2, AUDIO_RATE);
+    mixer.FinishMixing();
+    FillBuffer(a, CHANNEL_LENGTH, GetLowValue<AudioDataValue>());
+    FillBuffer(a + CHANNEL_LENGTH, CHANNEL_LENGTH, GetHighValue<AudioDataValue>());
+    FillBuffer(b, CHANNEL_LENGTH, GetHighValue<AudioDataValue>());
+    FillBuffer(b + CHANNEL_LENGTH, CHANNEL_LENGTH, GetLowValue<AudioDataValue>());
+    mixer.Mix(a, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.FinishMixing();
+    FillBuffer(a, CHANNEL_LENGTH / 2, GetLowValue<AudioDataValue>());
+    FillBuffer(a + CHANNEL_LENGTH / 2, CHANNEL_LENGTH / 2, GetLowValue<AudioDataValue>());
+    FillBuffer(b, CHANNEL_LENGTH / 2, GetHighValue<AudioDataValue>());
+    FillBuffer(b + CHANNEL_LENGTH / 2, CHANNEL_LENGTH / 2, GetHighValue<AudioDataValue>());
+    mixer.Mix(a, 2, CHANNEL_LENGTH / 2, AUDIO_RATE);
+    mixer.Mix(b, 2, CHANNEL_LENGTH / 2, AUDIO_RATE);
+    mixer.FinishMixing();
+  }
+
+  FillBuffer(a, CHANNEL_LENGTH, GetLowValue<AudioDataValue>());
+  FillBuffer(b, CHANNEL_LENGTH, GetHighValue<AudioDataValue>());
+
+  {
+    mozilla::AudioMixer mixer(MixingDone);
+    fprintf(stderr, "Test AudioMixer variable channel count.\n");
+
+    mixer.Mix(a, 1, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 1, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.FinishMixing();
+    mixer.Mix(a, 1, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 1, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.FinishMixing();
+    mixer.Mix(a, 1, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 1, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.FinishMixing();
+  }
+
+  {
+    mozilla::AudioMixer mixer(MixingDone);
+    fprintf(stderr, "Test AudioMixer variable stream count.\n");
+
+    mixer.Mix(a, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.FinishMixing();
+    mixer.Mix(a, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(a, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.FinishMixing();
+    mixer.Mix(a, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.Mix(b, 2, CHANNEL_LENGTH, AUDIO_RATE);
+    mixer.FinishMixing();
+  }
+
+  return 0;
+}
+