commit 2048c2292c0466b184fb8f67c91f4d0ab9f5c3f3
author Haynes Mathew George <hgeorge@codeaurora.org> Wed Jan 08 13:59:53 2014 -0800
committer Eric Laurent <elaurent@google.com> Thu Mar 06 18:00:39 2014 -0800
tree 126fcbfff298dd8e0f8ddb834c93c8850b8654ac
parent a11111f9135c98cf4247bbd1a61d7df3053e549e

AudioTrack: When paused, return cached playback position

An offload output can be re-used between two audio tracks having
the same configuration. A timestamp query for a paused track
while the other is running would return an incorrect time.
To fix this, cache the playback position on a pause() and return
this time when requested until the track is resumed.

Bug: 12826612.
Change-Id: Ia42b8b8fd2ba8993dfcc9abca72da48d71d78d74

include/media/AudioTrack.h

diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index f6646ab..4736369 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -740,6 +740,7 @@
 
     bool                    mInUnderrun;            // whether track is currently in underrun state
     String8                 mName;                  // server's name for this IAudioTrack
+    uint32_t                mPausedPosition;
 
 private:
     class DeathNotifier : public IBinder::DeathRecipient {

media/libmedia/AudioTrack.cpp

diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 11b0b89..e0e1a73 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -85,7 +85,8 @@
     : mStatus(NO_INIT),
       mIsTimed(false),
       mPreviousPriority(ANDROID_PRIORITY_NORMAL),
-      mPreviousSchedulingGroup(SP_DEFAULT)
+      mPreviousSchedulingGroup(SP_DEFAULT),
+      mPausedPosition(0)
 {
 }
 
@@ -106,7 +107,8 @@
     : mStatus(NO_INIT),
       mIsTimed(false),
       mPreviousPriority(ANDROID_PRIORITY_NORMAL),
-      mPreviousSchedulingGroup(SP_DEFAULT)
+      mPreviousSchedulingGroup(SP_DEFAULT),
+      mPausedPosition(0)
 {
     mStatus = set(streamType, sampleRate, format, channelMask,
             frameCount, flags, cbf, user, notificationFrames,
@@ -131,7 +133,8 @@
     : mStatus(NO_INIT),
       mIsTimed(false),
       mPreviousPriority(ANDROID_PRIORITY_NORMAL),
-      mPreviousSchedulingGroup(SP_DEFAULT)
+      mPreviousSchedulingGroup(SP_DEFAULT),
+      mPausedPosition(0)
 {
     mStatus = set(streamType, sampleRate, format, channelMask,
             0 /*frameCount*/, flags, cbf, user, notificationFrames,
@@ -529,6 +532,16 @@
     }
     mProxy->interrupt();
     mAudioTrack->pause();
+
+    if (isOffloaded()) {
+        if (mOutput != 0) {
+            uint32_t halFrames;
+            // OffloadThread sends HAL pause in its threadLoop.. time saved
+            // here can be slightly off
+            AudioSystem::getRenderPosition(mOutput, &halFrames, &mPausedPosition);
+            ALOGV("AudioTrack::pause for offload, cache current position %u", mPausedPosition);
+        }
+    }
 }
 
 status_t AudioTrack::setVolume(float left, float right)
@@ -747,6 +760,12 @@
     if (isOffloaded()) {
         uint32_t dspFrames = 0;
 
+        if ((mState == STATE_PAUSED) || (mState == STATE_PAUSED_STOPPING)) {
+            ALOGV("getPosition called in paused state, return cached position %u", mPausedPosition);
+            *position = mPausedPosition;
+            return NO_ERROR;
+        }
+
         if (mOutput != 0) {
             uint32_t halFrames;
             AudioSystem::getRenderPosition(mOutput, &halFrames, &dspFrames);