diff options
Diffstat (limited to 'media/libmedia')
| -rw-r--r-- | media/libmedia/AudioTrack.cpp | 91 |
1 files changed, 73 insertions, 18 deletions
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp index d87e6f5..ff7da83 100644 --- a/media/libmedia/AudioTrack.cpp +++ b/media/libmedia/AudioTrack.cpp @@ -398,7 +398,7 @@ status_t AudioTrack::set( } // create the IAudioTrack - status = createTrack_l(0 /*epoch*/); + status = createTrack_l(); if (status != NO_ERROR) { if (mAudioTrackThread != 0) { @@ -417,6 +417,9 @@ status_t AudioTrack::set( mMarkerReached = false; mNewPosition = 0; mUpdatePeriod = 0; + mServer = 0; + mPosition = 0; + mReleased = 0; AudioSystem::acquireAudioSessionId(mSessionId, mClientPid); mSequence = 1; mObservedSequence = mSequence; @@ -443,14 +446,16 @@ status_t AudioTrack::start() } else { mState = STATE_ACTIVE; } + (void) updateAndGetPosition_l(); if (previousState == STATE_STOPPED || previousState == STATE_FLUSHED) { // reset current position as seen by client to 0 - mProxy->setEpoch(mProxy->getEpoch() - mProxy->getPosition()); + mPosition = 0; + mReleased = 0; // force refresh of remaining frames by processAudioBuffer() as last // write before stop could be partial. mRefreshRemaining = true; } - mNewPosition = mProxy->getPosition() + mUpdatePeriod; + mNewPosition = mPosition + mUpdatePeriod; int32_t flags = android_atomic_and(~CBLK_DISABLED, &mCblk->mFlags); sp<AudioTrackThread> t = mAudioTrackThread; @@ -709,7 +714,7 @@ void AudioTrack::setLoop_l(uint32_t loopStart, uint32_t loopEnd, int loopCount) { // FIXME If setting a loop also sets position to start of loop, then // this is correct. Otherwise it should be removed. - mNewPosition = mProxy->getPosition() + mUpdatePeriod; + mNewPosition = updateAndGetPosition_l() + mUpdatePeriod; mLoopPeriod = loopCount != 0 ? loopEnd - loopStart : 0; mStaticProxy->setLoop(loopStart, loopEnd, loopCount); } @@ -751,7 +756,7 @@ status_t AudioTrack::setPositionUpdatePeriod(uint32_t updatePeriod) } AutoMutex lock(mLock); - mNewPosition = mProxy->getPosition() + updatePeriod; + mNewPosition = updateAndGetPosition_l() + updatePeriod; mUpdatePeriod = updatePeriod; return NO_ERROR; @@ -791,7 +796,7 @@ status_t AudioTrack::setPosition(uint32_t position) if (mState == STATE_ACTIVE) { return INVALID_OPERATION; } - mNewPosition = mProxy->getPosition() + mUpdatePeriod; + mNewPosition = updateAndGetPosition_l() + mUpdatePeriod; mLoopPeriod = 0; // FIXME Check whether loops and setting position are incompatible in old code. // If we use setLoop for both purposes we lose the capability to set the position while looping. @@ -800,7 +805,7 @@ status_t AudioTrack::setPosition(uint32_t position) return NO_ERROR; } -status_t AudioTrack::getPosition(uint32_t *position) const +status_t AudioTrack::getPosition(uint32_t *position) { if (position == NULL) { return BAD_VALUE; @@ -823,8 +828,8 @@ status_t AudioTrack::getPosition(uint32_t *position) const *position = dspFrames; } else { // IAudioTrack::stop() isn't synchronous; we don't know when presentation completes - *position = (mState == STATE_STOPPED || mState == STATE_FLUSHED) ? 0 : - mProxy->getPosition(); + *position = (mState == STATE_STOPPED || mState == STATE_FLUSHED) ? + 0 : updateAndGetPosition_l(); } return NO_ERROR; } @@ -881,7 +886,7 @@ status_t AudioTrack::attachAuxEffect(int effectId) // ------------------------------------------------------------------------- // must be called with mLock held -status_t AudioTrack::createTrack_l(size_t epoch) +status_t AudioTrack::createTrack_l() { status_t status; const sp<IAudioFlinger>& audioFlinger = AudioSystem::get_audio_flinger(); @@ -1184,7 +1189,6 @@ status_t AudioTrack::createTrack_l(size_t epoch) mProxy->setVolumeLR(GAIN_MINIFLOAT_PACKED_UNITY); mProxy->setSendLevel(mSendLevel); mProxy->setSampleRate(mSampleRate); - mProxy->setEpoch(epoch); mProxy->setMinimum(mNotificationFramesAct); mDeathNotifier = new DeathNotifier(this); @@ -1319,6 +1323,7 @@ void AudioTrack::releaseBuffer(Buffer* audioBuffer) buffer.mRaw = audioBuffer->raw; AutoMutex lock(mLock); + mReleased += stepCount; mInUnderrun = false; mProxy->releaseBuffer(&buffer); @@ -1531,7 +1536,7 @@ nsecs_t AudioTrack::processAudioBuffer() } // Get current position of server - size_t position = mProxy->getPosition(); + size_t position = updateAndGetPosition_l(); // Manage marker callback bool markerReached = false; @@ -1796,14 +1801,18 @@ status_t AudioTrack::restoreTrack_l(const char *from) return DEAD_OBJECT; } - // if the new IAudioTrack is created, createTrack_l() will modify the + // save the old static buffer position + size_t bufferPosition = mStaticProxy != NULL ? mStaticProxy->getBufferPosition() : 0; + + // If a new IAudioTrack is successfully created, createTrack_l() will modify the // following member variables: mAudioTrack, mCblkMemory and mCblk. - // It will also delete the strong references on previous IAudioTrack and IMemory + // It will also delete the strong references on previous IAudioTrack and IMemory. + // If a new IAudioTrack cannot be created, the previous (dead) instance will be left intact. + result = createTrack_l(); // take the frames that will be lost by track recreation into account in saved position - size_t position = mProxy->getPosition() + mProxy->getFramesFilled(); - size_t bufferPosition = mStaticProxy != NULL ? mStaticProxy->getBufferPosition() : 0; - result = createTrack_l(position /*epoch*/); + (void) updateAndGetPosition_l(); + mPosition = mReleased; if (result == NO_ERROR) { // continue playback from last known position, but @@ -1838,6 +1847,27 @@ status_t AudioTrack::restoreTrack_l(const char *from) return result; } +uint32_t AudioTrack::updateAndGetPosition_l() +{ + // This is the sole place to read server consumed frames + uint32_t newServer = mProxy->getPosition(); + int32_t delta = newServer - mServer; + mServer = newServer; + // TODO There is controversy about whether there can be "negative jitter" in server position. + // This should be investigated further, and if possible, it should be addressed. + // A more definite failure mode is infrequent polling by client. + // One could call (void)getPosition_l() in releaseBuffer(), + // so mReleased and mPosition are always lock-step as best possible. + // That should ensure delta never goes negative for infrequent polling + // unless the server has more than 2^31 frames in its buffer, + // in which case the use of uint32_t for these counters has bigger issues. + if (delta < 0) { + ALOGE("detected illegal retrograde motion by the server: mServer advanced by %d", delta); + delta = 0; + } + return mPosition += (uint32_t) delta; +} + status_t AudioTrack::setParameters(const String8& keyValuePairs) { AutoMutex lock(mLock); @@ -1854,9 +1884,34 @@ status_t AudioTrack::getTimestamp(AudioTimestamp& timestamp) if (mState != STATE_ACTIVE && mState != STATE_PAUSED) { return INVALID_OPERATION; } + // The presented frame count must always lag behind the consumed frame count. + // To avoid a race, read the presented frames first. This ensures that presented <= consumed. status_t status = mAudioTrack->getTimestamp(timestamp); if (status == NO_ERROR) { - timestamp.mPosition += mProxy->getEpoch(); + // Update the mapping between local consumed (mPosition) and server consumed (mServer) + (void) updateAndGetPosition_l(); + // Server consumed (mServer) and presented both use the same server time base, + // and server consumed is always >= presented. + // The delta between these represents the number of frames in the buffer pipeline. + // If this delta between these is greater than the client position, it means that + // actually presented is still stuck at the starting line (figuratively speaking), + // waiting for the first frame to go by. So we can't report a valid timestamp yet. + if ((uint32_t) (mServer - timestamp.mPosition) > mPosition) { + return INVALID_OPERATION; + } + // Convert timestamp position from server time base to client time base. + // TODO The following code should work OK now because timestamp.mPosition is 32-bit. + // But if we change it to 64-bit then this could fail. + // If (mPosition - mServer) can be negative then should use: + // (int32_t)(mPosition - mServer) + timestamp.mPosition += mPosition - mServer; + // Immediately after a call to getPosition_l(), mPosition and + // mServer both represent the same frame position. mPosition is + // in client's point of view, and mServer is in server's point of + // view. So the difference between them is the "fudge factor" + // between client and server views due to stop() and/or new + // IAudioTrack. And timestamp.mPosition is initially in server's + // point of view, so we need to apply the same fudge factor to it. } return status; } |