Increase kFastTrackMultiplier from 1 to 2
Change-Id: I158f147295eebcea96e4047d7618069bc48bdd7d
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index fe5cd9e..2965b73 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -857,7 +857,8 @@
ALOGV("createTrack_l() output %d afLatency %d", output, afLatency);
// The client's AudioTrack buffer is divided into n parts for purpose of wakeup by server, where
- // n = 1 fast track; nBuffering is ignored
+ // n = 1 fast track with single buffering; nBuffering is ignored
+ // n = 2 fast track with double buffering
// n = 2 normal track, no sample rate conversion
// n = 3 normal track, with sample rate conversion
// (pessimistic; some non-1:1 conversion ratios don't actually need triple-buffering)
@@ -996,9 +997,11 @@
ALOGV("AUDIO_OUTPUT_FLAG_FAST successful; frameCount %u", frameCount);
mAwaitBoost = true;
if (sharedBuffer == 0) {
- // double-buffering is not required for fast tracks, due to tighter scheduling
- if (mNotificationFramesAct == 0 || mNotificationFramesAct > frameCount) {
- mNotificationFramesAct = frameCount;
+ // Theoretically double-buffering is not required for fast tracks,
+ // due to tighter scheduling. But in practice, to accommodate kernels with
+ // scheduling jitter, and apps with computation jitter, we use double-buffering.
+ if (mNotificationFramesAct == 0 || mNotificationFramesAct > frameCount/nBuffering) {
+ mNotificationFramesAct = frameCount/nBuffering;
}
}
} else {
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 47dcca6..31d736a 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -135,12 +135,12 @@
// IAudioFlinger::createTrack() reports back to client the total size of shared memory area
// for the track. The client then sub-divides this into smaller buffers for its use.
-// Currently the client uses double-buffering by default, but doesn't tell us about that.
-// So for now we just assume that client is double-buffered.
-// FIXME It would be better for client to tell AudioFlinger whether it wants double-buffering or
-// N-buffering, so AudioFlinger could allocate the right amount of memory.
+// Currently the client uses N-buffering by default, but doesn't tell us about the value of N.
+// So for now we just assume that client is double-buffered for fast tracks.
+// FIXME It would be better for client to tell AudioFlinger the value of N,
+// so AudioFlinger could allocate the right amount of memory.
// See the client's minBufCount and mNotificationFramesAct calculations for details.
-static const int kFastTrackMultiplier = 1;
+static const int kFastTrackMultiplier = 2;
// ----------------------------------------------------------------------------
@@ -1182,7 +1182,7 @@
(
(tid != -1) &&
((frameCount == 0) ||
- (frameCount >= (mFrameCount * kFastTrackMultiplier)))
+ (frameCount >= mFrameCount))
)
) &&
// PCM data
@@ -4604,7 +4604,7 @@
(
(tid != -1) &&
((frameCount == 0) ||
- (frameCount >= (mFrameCount * kFastTrackMultiplier)))
+ (frameCount >= mFrameCount))
) &&
// FIXME when record supports non-PCM data, also check for audio_is_linear_pcm(format)
// mono or stereo