NS_IMETHODIMP
MediaEngineDefaultAudioSource::Notify(nsITimer* aTimer)
{
TimeStamp now = TimeStamp::Now();
TimeDuration timeSinceLastNotify = now - mLastNotify;
mLastNotify = now;
TrackTicks samplesSinceLastNotify =
RateConvertTicksRoundUp(AUDIO_RATE, 1000000, timeSinceLastNotify.ToMicroseconds());
// If it's been longer since the last Notify() than mBufferSize holds, we
// have underrun and the MSG had to append silence while waiting for us
// to push more data. In this case we reset to mBufferSize again.
TrackTicks samplesToAppend = std::min(samplesSinceLastNotify, mBufferSize);
AudioSegment segment;
AppendToSegment(segment, samplesToAppend);
mSource->AppendToTrack(mTrackID, &segment);
// Generate null data for fake tracks.
if (mHasFakeTracks) {
for (int i = 0; i < kFakeAudioTrackCount; ++i) {
AudioSegment nullSegment;
nullSegment.AppendNullData(samplesToAppend);
mSource->AppendToTrack(kTrackCount + kFakeVideoTrackCount+i, &nullSegment);
}
}
return NS_OK;
}
nsresult
MediaEngineDefaultAudioSource::Start(SourceMediaStream* aStream, TrackID aID,
const PrincipalHandle& aPrincipalHandle)
{
if (mState != kAllocated) {
return NS_ERROR_FAILURE;
}
mTimer = do_CreateInstance(NS_TIMER_CONTRACTID);
if (!mTimer) {
return NS_ERROR_FAILURE;
}
mSource = aStream;
// We try to keep the appended data at this size.
// Make it two timer intervals to try to avoid underruns.
mBufferSize = 2 * (AUDIO_RATE * DEFAULT_AUDIO_TIMER_MS) / 1000;
// AddTrack will take ownership of segment
AudioSegment* segment = new AudioSegment();
AppendToSegment(*segment, mBufferSize);
mSource->AddAudioTrack(aID, AUDIO_RATE, 0, segment, SourceMediaStream::ADDTRACK_QUEUED);
if (mHasFakeTracks) {
for (int i = 0; i < kFakeAudioTrackCount; ++i) {
segment = new AudioSegment();
segment->AppendNullData(mBufferSize);
mSource->AddAudioTrack(kTrackCount + kFakeVideoTrackCount+i,
AUDIO_RATE, 0, segment, SourceMediaStream::ADDTRACK_QUEUED);
}
}
// Remember TrackID so we can finish later
mTrackID = aID;
// Remember PrincipalHandle since we don't append in NotifyPull.
mPrincipalHandle = aPrincipalHandle;
mLastNotify = TimeStamp::Now();
// 1 Audio frame per 10ms
#if defined(MOZ_WIDGET_GONK) && defined(DEBUG)
// B2G emulator debug is very, very slow and has problems dealing with realtime audio inputs
mTimer->InitWithCallback(this, DEFAULT_AUDIO_TIMER_MS*10,
nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP);
#else
mTimer->InitWithCallback(this, DEFAULT_AUDIO_TIMER_MS,
nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP);
#endif
mState = kStarted;
return NS_OK;
}
void
MediaEngineDefaultAudioSource::NotifyPull(MediaStreamGraph* aGraph,
SourceMediaStream *aSource,
TrackID aID,
StreamTime aDesiredTime,
const PrincipalHandle& aPrincipalHandle)
{
MOZ_ASSERT(aID == mTrackID);
AudioSegment segment;
// avoid accumulating rounding errors
TrackTicks desired = aSource->TimeToTicksRoundUp(AUDIO_RATE, aDesiredTime);
TrackTicks delta = desired - mLastNotify;
mLastNotify += delta;
AppendToSegment(segment, delta, aPrincipalHandle);
aSource->AppendToTrack(mTrackID, &segment);
}
