static void EmptyAudioCallback(void * userdata, unsigned char * stream, int length)
{
SDL_memset(stream, 0, length);
AudioMixer * mixer = (class AudioMixer *)userdata;
if (mixer)
{
mixer->Mix(stream, length);
}
}
void
AudioSegment::WriteTo(uint64_t aID, AudioMixer& aMixer, uint32_t aOutputChannels, uint32_t aSampleRate)
{
nsAutoTArray<AudioDataValue,AUDIO_PROCESSING_FRAMES*GUESS_AUDIO_CHANNELS> buf;
nsAutoTArray<const void*,GUESS_AUDIO_CHANNELS> channelData;
// Offset in the buffer that will end up sent to the AudioStream, in samples.
uint32_t offset = 0;
if (GetDuration() <= 0) {
MOZ_ASSERT(GetDuration() == 0);
return;
}
uint32_t outBufferLength = GetDuration() * aOutputChannels;
buf.SetLength(outBufferLength);
for (ChunkIterator ci(*this); !ci.IsEnded(); ci.Next()) {
AudioChunk& c = *ci;
uint32_t frames = c.mDuration;
// If we have written data in the past, or we have real (non-silent) data
// to write, we can proceed. Otherwise, it means we just started the
// AudioStream, and we don't have real data to write to it (just silence).
// To avoid overbuffering in the AudioStream, we simply drop the silence,
// here. The stream will underrun and output silence anyways.
if (c.mBuffer && c.mBufferFormat != AUDIO_FORMAT_SILENCE) {
channelData.SetLength(c.mChannelData.Length());
for (uint32_t i = 0; i < channelData.Length(); ++i) {
channelData[i] = c.mChannelData[i];
}
if (channelData.Length() < aOutputChannels) {
// Up-mix. Note that this might actually make channelData have more
// than aOutputChannels temporarily.
AudioChannelsUpMix(&channelData, aOutputChannels, gZeroChannel);
}
if (channelData.Length() > aOutputChannels) {
// Down-mix.
DownmixAndInterleave(channelData, c.mBufferFormat, frames,
c.mVolume, aOutputChannels, buf.Elements() + offset);
} else {
InterleaveAndConvertBuffer(channelData.Elements(), c.mBufferFormat,
frames, c.mVolume,
aOutputChannels,
buf.Elements() + offset);
}
} else {
// Assumes that a bit pattern of zeroes == 0.0f
memset(buf.Elements() + offset, 0, aOutputChannels * frames * sizeof(AudioDataValue));
}
offset += frames * aOutputChannels;
#if !defined(MOZILLA_XPCOMRT_API)
if (!c.mTimeStamp.IsNull()) {
TimeStamp now = TimeStamp::Now();
// would be more efficient to c.mTimeStamp to ms on create time then pass here
LogTime(AsyncLatencyLogger::AudioMediaStreamTrack, aID,
(now - c.mTimeStamp).ToMilliseconds(), c.mTimeStamp);
}
#endif // !defined(MOZILLA_XPCOMRT_API)
}
if (offset) {
aMixer.Mix(buf.Elements(), aOutputChannels, offset / aOutputChannels, aSampleRate);
}
}