Bug 1487797 - Part 2: Make sure the time of audio data are monotonically increasing r=jya

Depends on D6425

Differential Revision: https://phabricator.services.mozilla.com/D6426

--HG--
extra : moz-landing-system : lando

dom/media/ReaderProxy.cpp

@@ -62,8 +62,9 @@ ReaderProxy::OnAudioDataRequestCompleted(RefPtr<AudioData> aAudio)
   int64_t offset =
     StartTime().ToMicroseconds() - mLoopingOffset.ToMicroseconds();
   aAudio->AdjustForStartTime(offset);
-  if (aAudio->mTime.IsValid() && aAudio->GetEndTime().IsValid()) {
-    mLastAudioEndTime = aAudio->GetEndTime();
+  if (aAudio->mTime.IsValid() && aAudio->GetEndTime().IsValid() &&
+      CorrectTimeOfAudioDataIfNeeded(aAudio)) {
+    UpdateLastAudioEndTime(aAudio);
     return AudioDataPromise::CreateAndResolve(aAudio.forget(), __func__);
   }
   return AudioDataPromise::CreateAndReject(NS_ERROR_DOM_MEDIA_OVERFLOW_ERR,
@@ -114,6 +115,28 @@ ReaderProxy::OnAudioDataRequestFailed(const MediaResult& aError)
            });
 }
 
+bool
+ReaderProxy::CorrectTimeOfAudioDataIfNeeded(const RefPtr<AudioData>& aAudio)
+{
+  MOZ_ASSERT(aAudio->mTime.IsValid() && mLastAudioEndTime.IsValid());
+  // The start time of the current audio data should be greater than the end
+  // time of the previous audio data.
+  if (aAudio->mTime < mLastAudioEndTime) {
+    aAudio->mTime = mLastAudioEndTime;
+  }
+  return aAudio->GetEndTime().IsValid();
+}
+
+void
+ReaderProxy::UpdateLastAudioEndTime(const AudioData* aAudio)
+{
+  MOZ_ASSERT(aAudio);
+  MOZ_ASSERT(aAudio->GetEndTime().IsValid() && mLastAudioEndTime.IsValid());
+  // Make sure the end time of the audio data are non-decreasing.
+  MOZ_ASSERT(aAudio->GetEndTime() >= mLastAudioEndTime);
+  mLastAudioEndTime = aAudio->GetEndTime();
+}
+
 RefPtr<ReaderProxy::AudioDataPromise>
 ReaderProxy::RequestAudioData()
 {

dom/media/ReaderProxy.h

@@ -100,6 +100,12 @@ private:
   RefPtr<ReaderProxy::AudioDataPromise> OnAudioDataRequestFailed(
     const MediaResult& aError);
 
+  // Make sure the timestamp of the audio data increase monotonically by
+  // adjusting it according to mLastAudioEndTime. Returns true if the
+  // endtime is valid after correction and false otherwise.
+  bool CorrectTimeOfAudioDataIfNeeded(const RefPtr<AudioData>& aAudio);
+  void UpdateLastAudioEndTime(const AudioData* aAudio);
+
   const RefPtr<AbstractThread> mOwnerThread;
   const RefPtr<MediaFormatReader> mReader;