commit 73e62e2ea12e46825958eba718bd8d5e23064ec5
author Andy Hung <hunga@google.com> Mon Apr 20 12:06:38 2015 -0700
committer Andy Hung <hunga@google.com> Tue Apr 21 15:28:48 2015 -0700
tree db5c4e3ffa06df9196ebbc4e5d3dff90e3c81b6a
parent 7184bab920699d49718e8fc3cf8a23d3c9d8d54a

Fix single channel playback that does not use AUDIO_CHANNEL_OUT_MONO

Mono channel playback without resampling and not using
AUDIO_CHANNEL_OUT_MONO can show low frequency garbling.

Bug: 20463456
Change-Id: I0c1bbf957ea439bb8d8da57b9e78938e1acb4793

services/audioflinger/AudioMixer.cpp

diff --git a/services/audioflinger/AudioMixer.cpp b/services/audioflinger/AudioMixer.cpp
index c2c791f..f28c625 100644
--- a/services/audioflinger/AudioMixer.cpp
+++ b/services/audioflinger/AudioMixer.cpp
@@ -319,7 +319,7 @@
 
     // discard the previous downmixer if there was one
     unprepareForDownmix();
-    // Only remix (upmix or downmix) if the track and mixer/device channel masks
+    // MONO_HACK Only remix (upmix or downmix) if the track and mixer/device channel masks
     // are not the same and not handled internally, as mono -> stereo currently is.
     if (channelMask == mMixerChannelMask
             || (channelMask == AUDIO_CHANNEL_OUT_MONO
@@ -914,7 +914,8 @@
             } else {
                 if ((n & NEEDS_CHANNEL_COUNT__MASK) == NEEDS_CHANNEL_1){
                     t.hook = getTrackHook(
-                            t.mMixerChannelCount == 2 // TODO: MONO_HACK.
+                            (t.mMixerChannelMask == AUDIO_CHANNEL_OUT_STEREO  // TODO: MONO_HACK
+                                    && t.channelMask == AUDIO_CHANNEL_OUT_MONO)
                                 ? TRACKTYPE_NORESAMPLEMONO : TRACKTYPE_NORESAMPLE,
                             t.mMixerChannelCount,
                             t.mMixerInFormat, t.mMixerFormat);