diff options
| -rw-r--r-- | media/libmedia/AudioTrack.cpp | 11 | ||||
| -rw-r--r-- | services/audioflinger/Threads.cpp | 14 |
2 files changed, 14 insertions, 11 deletions
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp index ccd1b49..11b0b89 100644 --- a/media/libmedia/AudioTrack.cpp +++ b/media/libmedia/AudioTrack.cpp @@ -879,7 +879,8 @@ status_t AudioTrack::createTrack_l( ALOGV("createTrack_l() output %d afLatency %d", output, afLatency); // The client's AudioTrack buffer is divided into n parts for purpose of wakeup by server, where - // n = 1 fast track; nBuffering is ignored + // n = 1 fast track with single buffering; nBuffering is ignored + // n = 2 fast track with double buffering // n = 2 normal track, no sample rate conversion // n = 3 normal track, with sample rate conversion // (pessimistic; some non-1:1 conversion ratios don't actually need triple-buffering) @@ -1019,9 +1020,11 @@ status_t AudioTrack::createTrack_l( ALOGV("AUDIO_OUTPUT_FLAG_FAST successful; frameCount %u", frameCount); mAwaitBoost = true; if (sharedBuffer == 0) { - // double-buffering is not required for fast tracks, due to tighter scheduling - if (mNotificationFramesAct == 0 || mNotificationFramesAct > frameCount) { - mNotificationFramesAct = frameCount; + // Theoretically double-buffering is not required for fast tracks, + // due to tighter scheduling. But in practice, to accommodate kernels with + // scheduling jitter, and apps with computation jitter, we use double-buffering. + if (mNotificationFramesAct == 0 || mNotificationFramesAct > frameCount/nBuffering) { + mNotificationFramesAct = frameCount/nBuffering; } } } else { diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp index 4f1c01d..3d657b3 100644 --- a/services/audioflinger/Threads.cpp +++ b/services/audioflinger/Threads.cpp @@ -135,12 +135,12 @@ static const int kPriorityFastMixer = 3; // IAudioFlinger::createTrack() reports back to client the total size of shared memory area // for the track. The client then sub-divides this into smaller buffers for its use. -// Currently the client uses double-buffering by default, but doesn't tell us about that. -// So for now we just assume that client is double-buffered. -// FIXME It would be better for client to tell AudioFlinger whether it wants double-buffering or -// N-buffering, so AudioFlinger could allocate the right amount of memory. +// Currently the client uses N-buffering by default, but doesn't tell us about the value of N. +// So for now we just assume that client is double-buffered for fast tracks. +// FIXME It would be better for client to tell AudioFlinger the value of N, +// so AudioFlinger could allocate the right amount of memory. // See the client's minBufCount and mNotificationFramesAct calculations for details. -static const int kFastTrackMultiplier = 1; +static const int kFastTrackMultiplier = 2; // ---------------------------------------------------------------------------- @@ -1210,7 +1210,7 @@ sp<AudioFlinger::PlaybackThread::Track> AudioFlinger::PlaybackThread::createTrac ( (tid != -1) && ((frameCount == 0) || - (frameCount >= (mFrameCount * kFastTrackMultiplier))) + (frameCount >= mFrameCount)) ) ) && // PCM data @@ -4687,7 +4687,7 @@ sp<AudioFlinger::RecordThread::RecordTrack> AudioFlinger::RecordThread::createR ( (tid != -1) && ((frameCount == 0) || - (frameCount >= (mFrameCount * kFastTrackMultiplier))) + (frameCount >= mFrameCount)) ) && // FIXME when record supports non-PCM data, also check for audio_is_linear_pcm(format) // mono or stereo |