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Bug 902856 - Generate fake audio data in MediaEngineDefaultAudioSource. r=jesup, r=derf

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This commit is contained in:
Steven Lee 2013-09-05 08:34:49 -04:00
parent 82495c079a
commit a516ca220b
2 changed files with 58 additions and 5 deletions
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60
content/media/webrtc/MediaEngineDefault.cpp
View File

@ -22,7 +22,7 @@
#define VIDEO_RATE USECS_PER_S
#define AUDIO_RATE 16000
#define AUDIO_FRAME_LENGTH ((AUDIO_RATE * MediaEngine::DEFAULT_AUDIO_TIMER_MS) / 1000)
namespace mozilla {
NS_IMPL_ISUPPORTS1(MediaEngineDefaultVideoSource, nsITimerCallback)
@ -258,6 +258,51 @@ MediaEngineDefaultVideoSource::NotifyPull(MediaStreamGraph* aGraph,
}
}
// generate 1k sine wave per second
class SineWaveGenerator : public RefCounted<SineWaveGenerator>
{
public:
static const int bytesPerSample = 2;
static const int millisecondsPerSecond = 1000;
static const int frequency = 1000;
SineWaveGenerator(int aSampleRate) :
mTotalLength(aSampleRate / frequency),
mReadLength(0) {
MOZ_ASSERT(mTotalLength * frequency == aSampleRate);
mAudioBuffer = new int16_t[mTotalLength];
for(int i = 0; i < mTotalLength; i++) {
// Set volume to -20db. It's from 32768.0 * 10^(-20/20) = 3276.8
mAudioBuffer[i] = (3276.8f * sin(2 * M_PI * i / mTotalLength));
}
}
void generate(int16_t* aBuffer, int16_t aLengthInSamples) {
int16_t remaining = aLengthInSamples;
while (remaining) {
int16_t processSamples = 0;
if (mTotalLength - mReadLength >= remaining) {
processSamples = remaining;
} else {
processSamples = mTotalLength - mReadLength;
}
memcpy(aBuffer, mAudioBuffer + mReadLength, processSamples * bytesPerSample);
aBuffer += processSamples;
mReadLength += processSamples;
remaining -= processSamples;
if (mReadLength == mTotalLength) {
mReadLength = 0;
}
}
}
private:
nsAutoArrayPtr<int16_t> mAudioBuffer;
int16_t mTotalLength;
int16_t mReadLength;
};
/**
* Default audio source.
@ -295,6 +340,8 @@ MediaEngineDefaultAudioSource::Allocate(const MediaEnginePrefs &aPrefs)
}
mState = kAllocated;
// generate 1Khz sine wave
mSineGenerator = new SineWaveGenerator(AUDIO_RATE);
return NS_OK;
}
@ -334,7 +381,7 @@ MediaEngineDefaultAudioSource::Start(SourceMediaStream* aStream, TrackID aID)
// 1 Audio frame per 10ms
mTimer->InitWithCallback(this, MediaEngine::DEFAULT_AUDIO_TIMER_MS,
nsITimer::TYPE_REPEATING_SLACK);
nsITimer::TYPE_REPEATING_PRECISE);
mState = kStarted;
return NS_OK;
@ -370,10 +417,13 @@ NS_IMETHODIMP
MediaEngineDefaultAudioSource::Notify(nsITimer* aTimer)
{
AudioSegment segment;
nsRefPtr<SharedBuffer> buffer = SharedBuffer::Create(AUDIO_FRAME_LENGTH * sizeof(int16_t));
int16_t* dest = static_cast<int16_t*>(buffer->Data());
// Notify timer is set every DEFAULT_AUDIO_TIMER_MS milliseconds.
segment.InsertNullDataAtStart((AUDIO_RATE * MediaEngine::DEFAULT_AUDIO_TIMER_MS) / 1000);
mSineGenerator->generate(dest, AUDIO_FRAME_LENGTH);
nsAutoTArray<const int16_t*,1> channels;
channels.AppendElement(dest);
segment.AppendFrames(buffer.forget(), channels, AUDIO_FRAME_LENGTH);
mSource->AppendToTrack(mTrackID, &segment);
return NS_OK;

3
content/media/webrtc/MediaEngineDefault.h
View File

@ -81,6 +81,8 @@ protected:
int mCr;
};
class SineWaveGenerator;
class MediaEngineDefaultAudioSource : public nsITimerCallback,
public MediaEngineAudioSource
{
@ -117,6 +119,7 @@ protected:
nsCOMPtr<nsITimer> mTimer;
SourceMediaStream* mSource;
nsRefPtr<SineWaveGenerator> mSineGenerator;
};