Merge "Clean up AudioTrack position and timestamp handling" into lmp-dev
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index a3cc396..72e51f9 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -430,7 +430,7 @@
* - NO_ERROR: successful operation
* - BAD_VALUE: position is NULL
*/
- status_t getPosition(uint32_t *position) const;
+ status_t getPosition(uint32_t *position);
/* For static buffer mode only, this returns the current playback position in frames
* relative to start of buffer. It is analogous to the position units used by
@@ -581,6 +581,7 @@
* if you need a high resolution mapping between frame position and presentation time,
* consider implementing that at application level, based on the low resolution timestamps.
* Returns NO_ERROR if timestamp is valid.
+ * The timestamp parameter is undefined on return, if status is not NO_ERROR.
*/
status_t getTimestamp(AudioTimestamp& timestamp);
@@ -639,7 +640,7 @@
// caller must hold lock on mLock for all _l methods
- status_t createTrack_l(size_t epoch);
+ status_t createTrack_l();
// can only be called when mState != STATE_ACTIVE
void flush_l();
@@ -659,6 +660,9 @@
bool isDirect_l() const
{ return (mFlags & AUDIO_OUTPUT_FLAG_DIRECT) != 0; }
+ // increment mPosition by the delta of mServer, and return new value of mPosition
+ uint32_t updateAndGetPosition_l();
+
// Next 4 fields may be changed if IAudioTrack is re-created, but always != 0
sp<IAudioTrack> mAudioTrack;
sp<IMemory> mCblkMemory;
@@ -731,6 +735,18 @@
bool mMarkerReached;
uint32_t mNewPosition; // in frames
uint32_t mUpdatePeriod; // in frames, zero means no EVENT_NEW_POS
+ uint32_t mServer; // in frames, last known mProxy->getPosition()
+ // which is count of frames consumed by server,
+ // reset by new IAudioTrack,
+ // whether it is reset by stop() is TBD
+ uint32_t mPosition; // in frames, like mServer except continues
+ // monotonically after new IAudioTrack,
+ // and could be easily widened to uint64_t
+ uint32_t mReleased; // in frames, count of frames released to server
+ // but not necessarily consumed by server,
+ // reset by stop() but continues monotonically
+ // after new IAudioTrack to restore mPosition,
+ // and could be easily widened to uint64_t
audio_output_flags_t mFlags;
// const after set(), except for bits AUDIO_OUTPUT_FLAG_FAST and AUDIO_OUTPUT_FLAG_OFFLOAD.
diff --git a/include/media/IAudioTrack.h b/include/media/IAudioTrack.h
index 5c8a484..619ac78 100644
--- a/include/media/IAudioTrack.h
+++ b/include/media/IAudioTrack.h
@@ -88,7 +88,7 @@
/* Send parameters to the audio hardware */
virtual status_t setParameters(const String8& keyValuePairs) = 0;
- /* Return NO_ERROR if timestamp is valid */
+ /* Return NO_ERROR if timestamp is valid. timestamp is undefined otherwise. */
virtual status_t getTimestamp(AudioTimestamp& timestamp) = 0;
/* Signal the playback thread for a change in control block */
diff --git a/include/media/nbaio/NBAIO.h b/include/media/nbaio/NBAIO.h
index be0c15b..d422576 100644
--- a/include/media/nbaio/NBAIO.h
+++ b/include/media/nbaio/NBAIO.h
@@ -227,7 +227,7 @@
// Returns NO_ERROR if a timestamp is available. The timestamp includes the total number
// of frames presented to an external observer, together with the value of CLOCK_MONOTONIC
- // as of this presentation count.
+ // as of this presentation count. The timestamp parameter is undefined if error is returned.
virtual status_t getTimestamp(AudioTimestamp& timestamp) { return INVALID_OPERATION; }
protected:
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 @@
}
// create the IAudioTrack
- status = createTrack_l(0 /*epoch*/);
+ status = createTrack_l();
if (status != NO_ERROR) {
if (mAudioTrackThread != 0) {
@@ -417,6 +417,9 @@
mMarkerReached = false;
mNewPosition = 0;
mUpdatePeriod = 0;
+ mServer = 0;
+ mPosition = 0;
+ mReleased = 0;
AudioSystem::acquireAudioSessionId(mSessionId, mClientPid);
mSequence = 1;
mObservedSequence = mSequence;
@@ -443,14 +446,16 @@
} 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 @@
{
// 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 @@
}
AutoMutex lock(mLock);
- mNewPosition = mProxy->getPosition() + updatePeriod;
+ mNewPosition = updateAndGetPosition_l() + updatePeriod;
mUpdatePeriod = updatePeriod;
return NO_ERROR;
@@ -791,7 +796,7 @@
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 @@
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 @@
*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 @@
// -------------------------------------------------------------------------
// 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 @@
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 @@
buffer.mRaw = audioBuffer->raw;
AutoMutex lock(mLock);
+ mReleased += stepCount;
mInUnderrun = false;
mProxy->releaseBuffer(&buffer);
@@ -1531,7 +1536,7 @@
}
// 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 @@
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 @@
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 @@
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;
}