audioflinger: fix clicks on 48kHz audio.

The calculation done in prepareTracks_l() for the minimum amount
off frames needed to mix one output buffer had 2 issues:
- the additional sample needed for interpolation was not included
- the fact that the resampler does not acknowledge the frames consumed
immediately after each mixing round but only once all frames requested have been used
was not taken into account.
Thus the number of frames available in track buffer could be considered sufficient although
it was not and the resampler would abort producing a short silence perceived as a click.

Issue 5727099.

Change-Id: I7419847a7474c7d9f9170bedd0a636132262142c

1 files changed, 17 insertions, 0 deletions

diff --git a/services/audioflinger/AudioMixer.cpp b/services/audioflinger/AudioMixer.cpp
index 6e9319d..1200f75 100644
--- a/services/audioflinger/AudioMixer.cpp
+++ b/services/audioflinger/AudioMixer.cpp
@@ -331,6 +331,23 @@ void AudioMixer::track_t::adjustVolumeRamp(bool aux)
     }
 }
 
+size_t AudioMixer::track_t::getUnreleasedFrames()
+{
+    if (resampler != NULL) {
+        return resampler->getUnreleasedFrames();
+    }
+    return 0;
+}
+
+size_t AudioMixer::getUnreleasedFrames(int name)
+{
+    name -= TRACK0;
+    if (uint32_t(name) < MAX_NUM_TRACKS) {
+        track_t& track(mState.tracks[name]);
+        return track.getUnreleasedFrames();
+    }
+    return 0;
+}
 
 status_t AudioMixer::setBufferProvider(AudioBufferProvider* buffer)
 {