Fix AudioTrack comments relating to use of restoreTrack_l()

Bug: 21699132
Change-Id: Ib0d029a5e28676aeffbbbafc88c52a17367a413c

2 files changed, 14 insertions, 4 deletions

diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index c0bc516..b897f2a 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -644,6 +644,12 @@ public:
      *      BAD_VALUE           size is invalid
      *      WOULD_BLOCK         when obtainBuffer() returns same, or
      *                          AudioTrack was stopped during the write
+     *      DEAD_OBJECT         when AudioFlinger dies or the output device changes and
+     *                          the track cannot be automatically restored.
+     *                          The application needs to recreate the AudioTrack
+     *                          because the audio device changed or AudioFlinger died.
+     *                          This typically occurs for direct or offload tracks
+     *                          or if mDoNotReconnect is true.
      *      or any other error code returned by IAudioTrack::start() or restoreTrack_l().
      * Default behavior is to only return when all data has been transferred. Set 'blocking' to
      * false for the method to return immediately without waiting to try multiple times to write
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 81ae6d7..949bc21 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -986,15 +986,18 @@ status_t AudioTrack::getPosition(uint32_t *position)
         }
 
         if (mOutput != AUDIO_IO_HANDLE_NONE) {
-            uint32_t halFrames;
-            AudioSystem::getRenderPosition(mOutput, &halFrames, &dspFrames);
+            uint32_t halFrames; // actually unused
+            (void) AudioSystem::getRenderPosition(mOutput, &halFrames, &dspFrames);
+            // FIXME: on getRenderPosition() error, we return OK with frame position 0.
         }
         // FIXME: dspFrames may not be zero in (mState == STATE_STOPPED || mState == STATE_FLUSHED)
         // due to hardware latency. We leave this behavior for now.
         *position = dspFrames;
     } else {
         if (mCblk->mFlags & CBLK_INVALID) {
-            restoreTrack_l("getPosition");
+            (void) restoreTrack_l("getPosition");
+            // FIXME: for compatibility with the Java API we ignore the restoreTrack_l()
+            // error here (e.g. DEAD_OBJECT) and return OK with the last recorded server position.
         }
 
         // IAudioTrack::stop() isn't synchronous; we don't know when presentation completes
@@ -2080,7 +2083,8 @@ status_t AudioTrack::restoreTrack_l(const char *from)
     AudioSystem::clearAudioConfigCache();
 
     if (isOffloadedOrDirect_l() || mDoNotReconnect) {
-        // FIXME re-creation of offloaded tracks is not yet implemented
+        // FIXME re-creation of offloaded and direct tracks is not yet implemented;
+        // reconsider enabling for linear PCM encodings when position can be preserved.
         return DEAD_OBJECT;
     }