commit ae9a5f1f1c15b894a762f66ff248fc840b7e72a5
author Mohan Kumar <mkumard@nvidia.com> Fri Dec 12 15:16:46 2014 +0530
committer Glenn Kasten <gkasten@google.com> Mon Mar 07 13:41:07 2016 -0800
tree f05aeb6b08783eef8a2e6f74750d2b6356d6772a
parent 844fab9b2b751fe7af8be64e55b912bec12e7c0b

audioflinger: clear mMixerBuffer if frame is not ready

Clear the mMixerBuffer if frame is not ready before the FastMixer
starts processing. Otherwise it might result in large glitches on
output device due to junk data present in the mixbuffer.

Change-Id: I9f025234d4ac100f85d2ec67c06a8df4195bea98

services/audioflinger/FastMixer.cpp

diff --git a/services/audioflinger/FastMixer.cpp b/services/audioflinger/FastMixer.cpp
index 45c68b5..2bc8066 100644
--- a/services/audioflinger/FastMixer.cpp
+++ b/services/audioflinger/FastMixer.cpp
@@ -334,6 +334,11 @@
 
     if ((command & FastMixerState::MIX) && (mMixer != NULL) && mIsWarm) {
         ALOG_ASSERT(mMixerBuffer != NULL);
+
+        // AudioMixer::mState.enabledTracks is undefined if mState.hook == process__validate,
+        // so we keep a side copy of enabledTracks
+        bool anyEnabledTracks = false;
+
         // for each track, update volume and check for underrun
         unsigned currentTrackMask = current->mTrackMask;
         while (currentTrackMask != 0) {
@@ -392,11 +397,13 @@
                     underruns.mBitFields.mPartial++;
                     underruns.mBitFields.mMostRecent = UNDERRUN_PARTIAL;
                     mMixer->enable(name);
+                    anyEnabledTracks = true;
                 }
             } else {
                 underruns.mBitFields.mFull++;
                 underruns.mBitFields.mMostRecent = UNDERRUN_FULL;
                 mMixer->enable(name);
+                anyEnabledTracks = true;
             }
             ftDump->mUnderruns = underruns;
             ftDump->mFramesReady = framesReady;
@@ -407,9 +414,14 @@
             pts = AudioBufferProvider::kInvalidPTS;
         }
 
-        // process() is CPU-bound
-        mMixer->process(pts);
-        mMixerBufferState = MIXED;
+        if (anyEnabledTracks) {
+            // process() is CPU-bound
+            mMixer->process(pts);
+            mMixerBufferState = MIXED;
+        } else if (mMixerBufferState != ZEROED) {
+            mMixerBufferState = UNDEFINED;
+        }
+
     } else if (mMixerBufferState == MIXED) {
         mMixerBufferState = UNDEFINED;
     }