Fix underruns when sample rate != native sample rate

This forces a minimum of 3 application buffers when the sample rates
don't match, using the normal mixer and low latency HAL.

There is still an issue that the latency() varies depending on whether
screen was off or on at the time of creating the AudioTrack.

With screen on:
I/AudioTrack( 2028): afFrameCount=960, minBufCount=2, afSampleRate=48000, afLatency=50
I/AudioTrack( 2028): minFrameCount: 2646, afFrameCount=960, minBufCount=3, sampleRate=44100, afSampleRate=48000, afLatency=50

With screen off:
I/AudioTrack( 2817): afFrameCount=960, minBufCount=4, afSampleRate=48000, afLatency=84
I/AudioTrack( 2817): minFrameCount: 3528, afFrameCount=960, minBufCount=4, sampleRate=44100, afSampleRate=48000, afLatency=84

Change-Id: Ib45515edff2afcd672dda34881b658c800ffc25a

1 files changed, 4 insertions, 2 deletions

diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index ff52b28..77fc6f6 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -861,8 +861,10 @@ status_t AudioTrack::createTrack_l(
 
         // Ensure that buffer depth covers at least audio hardware latency
         uint32_t minBufCount = afLatency / ((1000 * afFrameCount)/afSampleRate);
-        if (minBufCount < 2) {
-            minBufCount = 2;
+        ALOGV("afFrameCount=%d, minBufCount=%d, afSampleRate=%u, afLatency=%d",
+                afFrameCount, minBufCount, afSampleRate, afLatency);
+        if (minBufCount <= 2) {
+            minBufCount = sampleRate == afSampleRate ? 2 : 3;
         }
 
         size_t minFrameCount = (afFrameCount*sampleRate*minBufCount)/afSampleRate;