AudioFlinger: fix timed audio
(cherry picked from commit e20ac92c564a2f4e8123885807abdf0a78de0dd7)
> AudioFlinger: fix timed audio
>
> Addresses Bug 6900517.
>
> Finish up support for timed audio in the new FastMixer world. Pay special
> attention to remaining lock-less and voluntary yield free on the FastMixer
> thread. This fixes audio playback for Q on JB.
>
> Change-Id: Iaf815e58a1b1d0a0190051794bec8dc5c9231785
> Signed-off-by: John Grossman <johngro@google.com>
Change-Id: I9bd687acc345a05867af48e71116690fdb0ce1b5
Signed-off-by: John Grossman <johngro@google.com>
diff --git a/services/audioflinger/MonoPipeReader.cpp b/services/audioflinger/MonoPipeReader.cpp
index b80d0c0..39a07de 100644
--- a/services/audioflinger/MonoPipeReader.cpp
+++ b/services/audioflinger/MonoPipeReader.cpp
@@ -43,11 +43,25 @@
return ret;
}
-ssize_t MonoPipeReader::read(void *buffer, size_t count)
+ssize_t MonoPipeReader::read(void *buffer, size_t count, int64_t readPTS)
{
+ // Compute the "next read PTS" and cache it. Callers of read pass a read
+ // PTS indicating the local time for which they are requesting data along
+ // with a count (which is the number of audio frames they are going to
+ // ultimately pass to the next stage of the pipeline). Offsetting readPTS
+ // by the duration of count will give us the readPTS which will be passed to
+ // us next time, assuming they system continues to operate in steady state
+ // with no discontinuities. We stash this value so it can be used by the
+ // MonoPipe writer to imlement getNextWriteTimestamp.
+ int64_t nextReadPTS;
+ nextReadPTS = mPipe->offsetTimestampByAudioFrames(readPTS, count);
+
// count == 0 is unlikely and not worth checking for explicitly; will be handled automatically
ssize_t red = availableToRead();
if (CC_UNLIKELY(red <= 0)) {
+ // Uh-oh, looks like we are underflowing. Update the next read PTS and
+ // get out.
+ mPipe->updateFrontAndNRPTS(mPipe->mFront, nextReadPTS);
return red;
}
if (CC_LIKELY((size_t) red > count)) {
@@ -66,7 +80,7 @@
memcpy((char *) buffer + (part1 << mBitShift), mPipe->mBuffer, part2 << mBitShift);
}
}
- android_atomic_release_store(red + mPipe->mFront, &mPipe->mFront);
+ mPipe->updateFrontAndNRPTS(red + mPipe->mFront, nextReadPTS);
mFramesRead += red;
}
return red;