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Commit 6d7b119a authored by Andy Hung's avatar Andy Hung
Browse files

Improve timestamp jitter fix 

Use last valid kernel timestamp on server side, not client side.

Bug: 28465713
Change-Id: I33590d6922980f288355f947bc56279245058429
parent 0b667e2f

include/media/AudioTimestamp.h

+10 −3
Original line number Diff line number Diff line
@@ -37,9 +37,16 @@ public: 
struct ExtendedTimestamp {

    enum Location {

        LOCATION_INVALID = -1,

        LOCATION_CLIENT,   // timestamp of last read frame from client-server track buffer

        LOCATION_SERVER,   // timestamp of newest frame from client-server track buffer

        // Locations in the audio playback / record pipeline.

        LOCATION_CLIENT,   // timestamp of last read frame from client-server track buffer.

        LOCATION_SERVER,   // timestamp of newest frame from client-server track buffer.

        LOCATION_KERNEL,   // timestamp of newest frame in the kernel (alsa) buffer.



        // Historical data: info when the kernel timestamp was OK (prior to the newest frame).

        // This may be useful when the newest frame kernel timestamp is unavailable.

        // Available for playback timestamps.

        LOCATION_SERVER_LASTKERNELOK, // timestamp of server the prior time kernel timestamp OK.

        LOCATION_KERNEL_LASTKERNELOK, // timestamp of kernel the prior time kernel timestamp OK.

        LOCATION_MAX       // for sizing arrays only

    };
@@ -101,7 +108,7 @@ struct ExtendedTimestamp { 
        // look for the closest-to-hw stage in the pipeline with a valid timestamp.

        // We omit LOCATION_CLIENT as we prefer at least LOCATION_SERVER based accuracy

        // when getting the best timestamp.

        for (int i = LOCATION_MAX - 1; i >= LOCATION_SERVER; --i) {

        for (int i = LOCATION_KERNEL; i >= LOCATION_SERVER; --i) {

            if (mTimeNs[i] > 0) {

                *position = mPosition[i];

                *time = mTimeNs[i] + mTimebaseOffset[timebase];

include/media/AudioTrack.h

+0 −1
Original line number Diff line number Diff line
@@ -1047,7 +1047,6 @@ protected: 
    bool                    mRetrogradeMotionReported; // reduce log spam

    AudioTimestamp          mPreviousTimestamp;     // used to detect retrograde motion

    ExtendedTimestamp::Location mPreviousLocation;  // location used for previous timestamp

    double                  mComputedLatencyMs;     // latency between server and kernel



    uint32_t                mUnderrunCountOffset;   // updated when restoring tracks

media/libmedia/AudioTrack.cpp

+10 −15
Original line number Diff line number Diff line
@@ -536,7 +536,6 @@ status_t AudioTrack::set( 
    mTimestampStartupGlitchReported = false;

    mRetrogradeMotionReported = false;

    mPreviousLocation = ExtendedTimestamp::LOCATION_INVALID;

    mComputedLatencyMs = 0.;

    mUnderrunCountOffset = 0;

    mFramesWritten = 0;

    mFramesWrittenServerOffset = 0;
@@ -570,7 +569,6 @@ status_t AudioTrack::start() 
        mTimestampStartupGlitchReported = false;

        mRetrogradeMotionReported = false;

        mPreviousLocation = ExtendedTimestamp::LOCATION_INVALID;

        mComputedLatencyMs = 0.;



        // read last server side position change via timestamp.

        ExtendedTimestamp ets;
@@ -2375,25 +2373,22 @@ status_t AudioTrack::getTimestamp(AudioTimestamp& timestamp) 
                if (location == ExtendedTimestamp::LOCATION_SERVER) {

                    ALOGW_IF(mPreviousLocation == ExtendedTimestamp::LOCATION_KERNEL,

                            "getTimestamp() location moved from kernel to server");

                    const double latencyMs = mComputedLatencyMs > 0.

                            ? mComputedLatencyMs : mAfLatency;

                    const int64_t frames =

                            int64_t(latencyMs * mSampleRate * mPlaybackRate.mSpeed / 1000);

                    ALOGV("mComputedLatencyMs:%lf  mAfLatency:%u  frame adjustment:%lld",

                            mComputedLatencyMs, mAfLatency, (long long)frames);

                            (ets.mTimeNs[ExtendedTimestamp::LOCATION_SERVER_LASTKERNELOK] < 0 ||

                            ets.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL_LASTKERNELOK] < 0)

                            ?

                            int64_t((double)mAfLatency * mSampleRate * mPlaybackRate.mSpeed

                                    / 1000)

                            :

                            (ets.mPosition[ExtendedTimestamp::LOCATION_SERVER_LASTKERNELOK]

                            - ets.mPosition[ExtendedTimestamp::LOCATION_KERNEL_LASTKERNELOK]);

                    ALOGV("frame adjustment:%lld  timestamp:%s",

                            (long long)frames, ets.toString().c_str());

                    if (frames >= ets.mPosition[location]) {

                        timestamp.mPosition = 0;

                    } else {

                        timestamp.mPosition = (uint32_t)(ets.mPosition[location] - frames);

                    }

                } else if (location == ExtendedTimestamp::LOCATION_KERNEL) {

                    const double bufferDiffMs =

                            (double)(ets.mPosition[ExtendedTimestamp::LOCATION_SERVER]

                                   - ets.mPosition[ExtendedTimestamp::LOCATION_KERNEL])

                                   * 1000 / ((double)mSampleRate * mPlaybackRate.mSpeed);

                    mComputedLatencyMs = bufferDiffMs > 0. ? bufferDiffMs : 0.;

                    ALOGV("mComputedLatencyMs:%lf  mAfLatency:%d",

                            mComputedLatencyMs, mAfLatency);

                }

                mPreviousLocation = location;

            } else {

services/audioflinger/Threads.cpp

+18 −0
Original line number Diff line number Diff line
@@ -2899,6 +2899,24 @@ bool AudioFlinger::PlaybackThread::threadLoop() 
                // sink will block whie writing.

                ExtendedTimestamp timestamp; // use private copy to fetch

                (void) mNormalSink->getTimestamp(timestamp);



                // We keep track of the last valid kernel position in case we are in underrun

                // and the normal mixer period is the same as the fast mixer period, or there

                // is some error from the HAL.

                if (mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL] >= 0) {

                    mTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL_LASTKERNELOK] =

                            mTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL];

                    mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL_LASTKERNELOK] =

                            mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_KERNEL];



                    mTimestamp.mPosition[ExtendedTimestamp::LOCATION_SERVER_LASTKERNELOK] =

                            mTimestamp.mPosition[ExtendedTimestamp::LOCATION_SERVER];

                    mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_SERVER_LASTKERNELOK] =

                            mTimestamp.mTimeNs[ExtendedTimestamp::LOCATION_SERVER];

                } else {

                    ALOGV("getTimestamp error - no valid kernel position");

                }



                // copy over kernel info

                mTimestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL] =

                        timestamp.mPosition[ExtendedTimestamp::LOCATION_KERNEL];

services/audioflinger/Tracks.cpp

+1 −1
Original line number Diff line number Diff line
@@ -1103,7 +1103,7 @@ void AudioFlinger::PlaybackThread::Track::updateTrackFrameInfo( 
        if (local.mTimeNs[i] > 0) {

            local.mPosition[i] = mFrameMap.findX(local.mPosition[i]);

            // check drain state from the latest stage in the pipeline.

            if (!checked) {

            if (!checked && i <= ExtendedTimestamp::LOCATION_KERNEL) {

                mAudioTrackServerProxy->setDrained(

                        local.mPosition[i] >= mAudioTrackServerProxy->framesReleased());

                checked = true;