Fix multichannel downmix pause bug on video player

Pausing a video player will cause the track audio mixer to be
 disabled, which causes the downmixer to be deleted. When reenabled,
 the track channel mask hasn't changed but the downmixer is there
 anymore.
Fixed by:
- instanciating a downmixer when the AudioMixer track
 gets initialized (in getTrackName(), now taking a channel mask
 as input), and deleted when in deleteTrackName().
- when the channel changes on a track, check whether it
 needs a downmixer or not. Preparing a track for downmix
 automatically removes the old downmixer if there was one.

Also: initialize the track downmixerBufferProvider field
 when AudioMixer is instanciated, so we can safely call
 delete on it in AudioMixer's destructor, in case
 deleteTrackName() wasn't called before the mixer was
 destroyed.

Change-Id: I589b0781cda5b3c82f85b561c52b08546cac21f8

1 files changed, 3 insertions, 1 deletions

diff --git a/services/audioflinger/AudioMixer.h b/services/audioflinger/AudioMixer.h
index 9698d0c..46deae7 100644
--- a/services/audioflinger/AudioMixer.h
+++ b/services/audioflinger/AudioMixer.h
@@ -91,7 +91,7 @@ public:
     // For all APIs with "name": TRACK0 <= name < TRACK0 + MAX_NUM_TRACKS
 
     // Allocate a track name.  Returns new track name if successful, -1 on failure.
-    int         getTrackName();
+    int         getTrackName(audio_channel_mask_t channelMask);
 
     // Free an allocated track by name
     void        deleteTrackName(int name);
@@ -250,7 +250,9 @@ private:
     // OK to call more often than that, but unnecessary.
     void invalidateState(uint32_t mask);
 
+    static status_t initTrackDownmix(track_t* pTrack, int trackNum, audio_channel_mask_t mask);
     static status_t prepareTrackForDownmix(track_t* pTrack, int trackNum);
+    static void unprepareTrackForDownmix(track_t* pTrack, int trackName);
 
     static void track__genericResample(track_t* t, int32_t* out, size_t numFrames, int32_t* temp, int32_t* aux);
     static void track__nop(track_t* t, int32_t* out, size_t numFrames, int32_t* temp, int32_t* aux);