audioflinger: multiple tracks on direct output

Fix problems when multiple tracks exist on a direct output
thread:  when multiple tracks are active, continue to update all
track states but only take into account the last track started
for audio HAL volume and mixer state control.

Bug 8388941

Change-Id: I57e6757286f41651dda99b11a5449e431812431b

1 files changed, 52 insertions, 45 deletions

diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 9d98f0b..47ca100 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -3122,16 +3122,15 @@ AudioFlinger::PlaybackThread::mixer_state AudioFlinger::DirectOutputThread::prep
     Vector< sp<Track> > *tracksToRemove
 )
 {
-    sp<Track> trackToRemove;
-
+    size_t count = mActiveTracks.size();
     mixer_state mixerStatus = MIXER_IDLE;
 
     // find out which tracks need to be processed
-    if (mActiveTracks.size() != 0) {
-        sp<Track> t = mActiveTracks[0].promote();
+    for (size_t i = 0; i < count; i++) {
+        sp<Track> t = mActiveTracks[i].promote();
         // The track died recently
         if (t == 0) {
-            return MIXER_IDLE;
+            continue;
         }
 
         Track* const track = t.get();
@@ -3180,35 +3179,40 @@ AudioFlinger::PlaybackThread::mixer_state AudioFlinger::DirectOutputThread::prep
                 }
                 right = v_clamped/MAX_GAIN;
             }
-
-            if (left != mLeftVolFloat || right != mRightVolFloat) {
-                mLeftVolFloat = left;
-                mRightVolFloat = right;
-
-                // Convert volumes from float to 8.24
-                uint32_t vl = (uint32_t)(left * (1 << 24));
-                uint32_t vr = (uint32_t)(right * (1 << 24));
-
-                // Delegate volume control to effect in track effect chain if needed
-                // only one effect chain can be present on DirectOutputThread, so if
-                // there is one, the track is connected to it
-                if (!mEffectChains.isEmpty()) {
-                    // Do not ramp volume if volume is controlled by effect
-                    mEffectChains[0]->setVolume_l(&vl, &vr);
-                    left = (float)vl / (1 << 24);
-                    right = (float)vr / (1 << 24);
+            // Only consider last track started for volume and mixer state control.
+            // This is the last entry in mActiveTracks unless a track underruns.
+            // As we only care about the transition phase between two tracks on a
+            // direct output, it is not a problem to ignore the underrun case.
+            if (i == (count - 1)) {
+                if (left != mLeftVolFloat || right != mRightVolFloat) {
+                    mLeftVolFloat = left;
+                    mRightVolFloat = right;
+
+                    // Convert volumes from float to 8.24
+                    uint32_t vl = (uint32_t)(left * (1 << 24));
+                    uint32_t vr = (uint32_t)(right * (1 << 24));
+
+                    // Delegate volume control to effect in track effect chain if needed
+                    // only one effect chain can be present on DirectOutputThread, so if
+                    // there is one, the track is connected to it
+                    if (!mEffectChains.isEmpty()) {
+                        // Do not ramp volume if volume is controlled by effect
+                        mEffectChains[0]->setVolume_l(&vl, &vr);
+                        left = (float)vl / (1 << 24);
+                        right = (float)vr / (1 << 24);
+                    }
+                    mOutput->stream->set_volume(mOutput->stream, left, right);
                 }
-                mOutput->stream->set_volume(mOutput->stream, left, right);
-            }
 
-            // reset retry count
-            track->mRetryCount = kMaxTrackRetriesDirect;
-            mActiveTrack = t;
-            mixerStatus = MIXER_TRACKS_READY;
+                // reset retry count
+                track->mRetryCount = kMaxTrackRetriesDirect;
+                mActiveTrack = t;
+                mixerStatus = MIXER_TRACKS_READY;
+            }
         } else {
-            // clear effect chain input buffer if an active track underruns to avoid sending
-            // previous audio buffer again to effects
-            if (!mEffectChains.isEmpty()) {
+            // clear effect chain input buffer if the last active track started underruns
+            // to avoid sending previous audio buffer again to effects
+            if (!mEffectChains.isEmpty() && (i == (count -1))) {
                 mEffectChains[0]->clearInputBuffer();
             }
 
@@ -3224,33 +3228,36 @@ AudioFlinger::PlaybackThread::mixer_state AudioFlinger::DirectOutputThread::prep
                     if (track->isStopped()) {
                         track->reset();
                     }
-                    trackToRemove = track;
+                    tracksToRemove->add(track);
                 }
             } else {
                 // No buffers for this track. Give it a few chances to
                 // fill a buffer, then remove it from active list.
+                // Only consider last track started for mixer state control
                 if (--(track->mRetryCount) <= 0) {
                     ALOGV("BUFFER TIMEOUT: remove(%d) from active list", track->name());
-                    trackToRemove = track;
-                } else {
+                    tracksToRemove->add(track);
+                } else if (i == (count -1)){
                     mixerStatus = MIXER_TRACKS_ENABLED;
                 }
             }
         }
     }
 
-    // FIXME merge this with similar code for removing multiple tracks
     // remove all the tracks that need to be...
-    if (CC_UNLIKELY(trackToRemove != 0)) {
-        tracksToRemove->add(trackToRemove);
-        mActiveTracks.remove(trackToRemove);
-        if (!mEffectChains.isEmpty()) {
-            ALOGV("stopping track on chain %p for session Id: %d", mEffectChains[0].get(),
-                    trackToRemove->sessionId());
-            mEffectChains[0]->decActiveTrackCnt();
-        }
-        if (trackToRemove->isTerminated()) {
-            removeTrack_l(trackToRemove);
+    count = tracksToRemove->size();
+    if (CC_UNLIKELY(count)) {
+        for (size_t i = 0 ; i < count ; i++) {
+            const sp<Track>& track = tracksToRemove->itemAt(i);
+            mActiveTracks.remove(track);
+            if (!mEffectChains.isEmpty()) {
+                ALOGV("stopping track on chain %p for session Id: %d", mEffectChains[0].get(),
+                      track->sessionId());
+                mEffectChains[0]->decActiveTrackCnt();
+            }
+            if (track->isTerminated()) {
+                removeTrack_l(track);
+            }
         }
     }