AudioTrack: Fix callback timing if less than one AF mixer period.
Callback may wait nearly the entire period when double buffered
which can lead to random glitches. Limit this to half the mixer period.
Test: aaudio test write_sine_callback -pl -n1 -r44100 -s20
Bug: 129545307
Bug: 131601263
Change-Id: I6b7478728fe7ead570251662ee48a8f8adad0d5d
diff --git a/media/libaudioclient/AudioTrack.cpp b/media/libaudioclient/AudioTrack.cpp
index bd48f56..0e8d139 100644
--- a/media/libaudioclient/AudioTrack.cpp
+++ b/media/libaudioclient/AudioTrack.cpp
@@ -2144,9 +2144,27 @@
const nsecs_t timeNow = systemTime();
ns = max((nsecs_t)0, ns - (timeNow - timeAfterCallbacks));
}
- nsecs_t myns = framesToNanoseconds(mRemainingFrames - avail, sampleRate, speed);
- if (ns < 0 /* NS_WHENEVER */ || myns < ns) {
- ns = myns;
+
+ // delayNs is first computed by the additional frames required in the buffer.
+ nsecs_t delayNs = framesToNanoseconds(
+ mRemainingFrames - avail, sampleRate, speed);
+
+ // afNs is the AudioFlinger mixer period in ns.
+ const nsecs_t afNs = framesToNanoseconds(mAfFrameCount, mAfSampleRate, speed);
+
+ // If the AudioTrack is double buffered based on the AudioFlinger mixer period,
+ // we may have a race if we wait based on the number of frames desired.
+ // This is a possible issue with resampling and AAudio.
+ //
+ // The granularity of audioflinger processing is one mixer period; if
+ // our wait time is less than one mixer period, wait at most half the period.
+ if (delayNs < afNs) {
+ delayNs = std::min(delayNs, afNs / 2);
+ }
+
+ // adjust our ns wait by delayNs.
+ if (ns < 0 /* NS_WHENEVER */ || delayNs < ns) {
+ ns = delayNs;
}
return ns;
}