Bug 1656438 - Take the desired buffering as parameter in ClockDrift, AudioResampler, and friends. r=padenot

This makes us able to write tests for different buffer lengths.

Differential Revision: https://phabricator.services.mozilla.com/D89760

dom/media/AudioDriftCorrection.h

@@ -36,15 +36,11 @@ class ClockDrift final {
   /**
    * Provide the nominal source and the target sample rate.
    */
-  ClockDrift(int32_t aSourceRate, int32_t aTargetRate)
+  ClockDrift(int32_t aSourceRate, int32_t aTargetRate,
+             int32_t aDesiredBuffering)
       : mSourceRate(aSourceRate),
         mTargetRate(aTargetRate),
-        mDesiredBuffering(5 * mSourceRate / 100) {
-    if (Preferences::HasUserValue("media.clockdrift.buffering")) {
-      int msecs = Preferences::GetInt("media.clockdrift.buffering");
-      mDesiredBuffering = msecs * mSourceRate / 100;
-    }
-  }
+        mDesiredBuffering(aDesiredBuffering) {}
 
   /**
    * The correction in the form of a ratio. A correction of 0.98 means that the
@@ -118,14 +114,15 @@ class ClockDrift final {
     mCorrection = std::min(std::max(mCorrection, 0.9f), 1.1f);
   }
 
- private:
+ public:
   const int32_t mSourceRate;
   const int32_t mTargetRate;
+  const int32_t mDesiredBuffering;
 
+ private:
   float mCorrection = 1.0;
   float mPreviousCorrection = 1.0;
   const int32_t mAdjustementWindow = 100;
-  int32_t mDesiredBuffering;  // defult: 5ms
 
   int32_t mSourceClock = 0;
   int32_t mTargetClock = 0;
@@ -154,9 +151,12 @@ class ClockDrift final {
 class AudioDriftCorrection final {
  public:
   AudioDriftCorrection(int32_t aSourceRate, int32_t aTargetRate)
-      : mClockDrift(aSourceRate, aTargetRate),
-        mResampler(aSourceRate, aTargetRate, aTargetRate / 20 /*50ms*/),
-        mTargetRate(aTargetRate) {}
+      : mDesiredBuffering(
+            std::max(1, Preferences::GetInt("media.clockdrift.buffering", 5)) *
+            aSourceRate / 1000),
+        mTargetRate(aTargetRate),
+        mClockDrift(aSourceRate, aTargetRate, mDesiredBuffering),
+        mResampler(aSourceRate, aTargetRate, mDesiredBuffering) {}
 
   /**
    * The source audio frames and request the number of target audio frames must
@@ -188,10 +188,12 @@ class AudioDriftCorrection final {
     return output;
   }
 
+  const int32_t mDesiredBuffering;
+  const int32_t mTargetRate;
+
  private:
   ClockDrift mClockDrift;
   AudioResampler mResampler;
-  const int32_t mTargetRate;
 };
 
 };     // namespace mozilla

dom/media/DynamicResampler.cpp

@@ -136,9 +136,10 @@ void DynamicResampler::UpdateResampler(int aOutRate, int aChannels) {
     // because allocates and this is executed in audio thread.
     mInternalInBuffer.Clear();
     for (int i = 0; i < mChannels; ++i) {
-      // Pre-allocate something big, 100ms of audio.
-      AudioRingBuffer* b =
-          mInternalInBuffer.AppendElement(sizeof(float) * mInRate / 10);
+      // Pre-allocate something big, twice the pre-buffer, or at least 100ms.
+      AudioRingBuffer* b = mInternalInBuffer.AppendElement(
+          sizeof(float) *
+          std::max(2 * mPreBufferFrames, static_cast<uint32_t>(mInRate) / 10));
       if (mSampleFormat != AUDIO_FORMAT_SILENCE) {
         // In ctor this update is not needed
         b->SetSampleFormat(mSampleFormat);

dom/media/gtest/TestAudioDriftCorrection.cpp

@@ -13,7 +13,10 @@
 
 TEST(TestClockDrift, Basic)
 {
-  ClockDrift c(48000, 48000);
+  // Keep buffered frames to the wanted level in order to not affect that test.
+  const int buffered = 5 * 480;
+
+  ClockDrift c(48000, 48000, buffered);
   EXPECT_EQ(c.GetCorrection(), 1.0);
 
   // Keep buffered frames to the wanted level in order to not affect that test.
@@ -43,7 +46,10 @@ TEST(TestClockDrift, Basic)
 
 TEST(TestClockDrift, BasicResampler)
 {
-  ClockDrift c(24000, 48000);
+  // Keep buffered frames to the wanted level in order to not affect that test.
+  const int buffered = 5 * 240;
+
+  ClockDrift c(24000, 48000, buffered);
   for (int i = 0; i < 100; ++i) {
     c.UpdateClock(240, 480, 5 * 240);
     EXPECT_FLOAT_EQ(c.GetCorrection(), 1.0);
@@ -76,7 +82,7 @@ TEST(TestClockDrift, BasicResampler)
 
 TEST(TestClockDrift, BufferedInput)
 {
-  ClockDrift c(48000, 48000);
+  ClockDrift c(48000, 48000, 5 * 480);
   EXPECT_EQ(c.GetCorrection(), 1.0);
 
   for (int i = 0; i < 100; ++i) {
@@ -110,7 +116,7 @@ TEST(TestClockDrift, BufferedInput)
 
 TEST(TestClockDrift, BufferedInputWithResampling)
 {
-  ClockDrift c(24000, 48000);
+  ClockDrift c(24000, 48000, 5 * 240);
   EXPECT_EQ(c.GetCorrection(), 1.0);
 
   for (int i = 0; i < 100; ++i) {
@@ -144,7 +150,10 @@ TEST(TestClockDrift, BufferedInputWithResampling)
 
 TEST(TestClockDrift, Clamp)
 {
-  ClockDrift c(48000, 48000);
+  // Keep buffered frames to the wanted level in order to not affect that test.
+  const int buffered = 5 * 480;
+
+  ClockDrift c(48000, 48000, buffered);
 
   for (int i = 0; i < 100; ++i) {
     c.UpdateClock(480, 480 + 2 * 48, 5 * 480);  // +20%
@@ -160,7 +169,10 @@ TEST(TestClockDrift, Clamp)
 
 TEST(TestClockDrift, SmallDiff)
 {
-  ClockDrift c(48000, 48000);
+  // Keep buffered frames to the wanted level in order to not affect that test.
+  const int buffered = 5 * 480;
+
+  ClockDrift c(48000, 48000, buffered);
 
   for (int i = 0; i < 100; ++i) {
     c.UpdateClock(480 + 4, 480, 5 * 480);
@@ -185,7 +197,7 @@ TEST(TestClockDrift, SmallDiff)
 
 TEST(TestClockDrift, SmallBufferedFrames)
 {
-  ClockDrift c(48000, 48000);
+  ClockDrift c(48000, 48000, 5 * 480);
 
   EXPECT_FLOAT_EQ(c.GetCorrection(), 1.0);
   c.UpdateClock(480, 480, 5 * 480);