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Commit e737cda6 authored by Eric Laurent's avatar Eric Laurent
Browse files

audioflinger: refine latency latency calculation. 

There is an audio pipe between the normal mixer output and the fast
mixer to cope for scheduling delays and buffer size difference.
This pipe depth was not taken into account in latency calculation.

Adding the pipe contribution to the latency significantly improves A/V sync.

Bug 6520569.

Change-Id: I5584908e8aa8a02170eb38b22b4370eea800a235
parent 8d9846c0

services/audioflinger/AudioFlinger.cpp

+16 −1
Original line number Diff line number Diff line
@@ -1804,11 +1804,25 @@ Exit: 
    return track;

}



uint32_t AudioFlinger::MixerThread::correctLatency(uint32_t latency) const

{

    if (mFastMixer != NULL) {

        MonoPipe *pipe = (MonoPipe *)mPipeSink.get();

        latency += (pipe->getAvgFrames() * 1000) / mSampleRate;

    }

    return latency;

}



uint32_t AudioFlinger::PlaybackThread::correctLatency(uint32_t latency) const

{

    return latency;

}



uint32_t AudioFlinger::PlaybackThread::latency() const

{

    Mutex::Autolock _l(mLock);

    if (initCheck() == NO_ERROR) {

        return mOutput->stream->get_latency(mOutput->stream);

        return correctLatency(mOutput->stream->get_latency(mOutput->stream));

    } else {

        return 0;

    }
@@ -2020,6 +2034,7 @@ void AudioFlinger::PlaybackThread::readOutputParameters() 
    }

}





status_t AudioFlinger::PlaybackThread::getRenderPosition(uint32_t *halFrames, uint32_t *dspFrames)

{

    if (halFrames == NULL || dspFrames == NULL) {

services/audioflinger/AudioFlinger.h

+3 −0
Original line number Diff line number Diff line
@@ -1048,6 +1048,8 @@ public: 
        // Cache various calculated values, at threadLoop() entry and after a parameter change

        virtual     void        cacheParameters_l();



        virtual     uint32_t    correctLatency(uint32_t latency) const;



    private:



        friend class AudioFlinger;      // for numerous
@@ -1154,6 +1156,7 @@ public: 
        virtual     void        threadLoop_mix();

        virtual     void        threadLoop_sleepTime();

        virtual     void        threadLoop_removeTracks(const Vector< sp<Track> >& tracksToRemove);

        virtual     uint32_t    correctLatency(uint32_t latency) const;



                    AudioMixer* mAudioMixer;    // normal mixer

    private:

services/audioflinger/MonoPipe.h

+4 −0
Original line number Diff line number Diff line
@@ -56,6 +56,10 @@ public: 
    virtual ssize_t write(const void *buffer, size_t count);

    //virtual ssize_t writeVia(writeVia_t via, size_t total, void *user, size_t block);



            // average number of frames present in the pipe under normal conditions.

            // See throttling mechanism in MonoPipe::write()

            size_t  getAvgFrames() const { return (mMaxFrames * 11) / 16; }



private:

    const size_t    mMaxFrames;     // always a power of 2

    void * const    mBuffer;