Fix issue 2139634: DTMF tones on Sholes popping, hissing (audio latency too high).

This change is a complement to the main fix in kernel driver for the same issue (partner change #1250).
It removes clicks sometimes heard after the end of the tones while audio flinger is sending 0s to the audio output stream.
The problem was that the sleep time between two writes was more than the duration of one audio output stream buffer which could cause some underrun.

Also fixed a recent regression in ToneGenerator that made that the end of previous tone was repeated at the beginning of current one under certain timing circumstances when the maximum tone duration was specified.

2 files changed, 81 insertions, 59 deletions

diff --git a/libs/audioflinger/AudioFlinger.cpp b/libs/audioflinger/AudioFlinger.cpp
index 8e967fb..ba8b322 100644
--- a/libs/audioflinger/AudioFlinger.cpp
+++ b/libs/audioflinger/AudioFlinger.cpp
@@ -62,8 +62,6 @@ static const char* kDeadlockedString = "AudioFlinger may be deadlocked\n";
 static const char* kHardwareLockedString = "Hardware lock is taken\n";
 
 //static const nsecs_t kStandbyTimeInNsecs = seconds(3);
-static const unsigned long kBufferRecoveryInUsecs = 2000;
-static const unsigned long kMaxBufferRecoveryInUsecs = 20000;
 static const float MAX_GAIN = 4096.0f;
 
 // retry counts for buffer fill timeout
@@ -1070,10 +1068,10 @@ status_t AudioFlinger::PlaybackThread::addTrack_l(const sp<Track>& track)
     // in both cases "unstop" the track
     if (track->isPaused()) {
         track->mState = TrackBase::RESUMING;
-        LOGV("PAUSED => RESUMING (%d)", track->name());
+        LOGV("PAUSED => RESUMING (%d) on thread %p", track->name(), this);
     } else {
         track->mState = TrackBase::ACTIVE;
-        LOGV("? => ACTIVE (%d)", track->name());
+        LOGV("? => ACTIVE (%d) on thread %p", track->name(), this);
     }
     // set retry count for buffer fill
     track->mRetryCount = kMaxTrackStartupRetries;
@@ -1175,7 +1173,8 @@ AudioFlinger::MixerThread::~MixerThread()
 
 bool AudioFlinger::MixerThread::threadLoop()
 {
-    unsigned long sleepTime = 0;
+    uint32_t sleepTime = 0;
+    uint32_t maxBufferRecoveryInUsecs = getMaxBufferRecoveryInUsecs();
     int16_t* curBuf = mMixBuffer;
     Vector< sp<Track> > tracksToRemove;
     size_t enabledTracks = 0;
@@ -1200,6 +1199,7 @@ bool AudioFlinger::MixerThread::threadLoop()
                 // FIXME: Relaxed timing because of a certain device that can't meet latency
                 // Should be reduced to 2x after the vendor fixes the driver issue
                 maxPeriod = seconds(mFrameCount) / mSampleRate * 3;
+                maxBufferRecoveryInUsecs = getMaxBufferRecoveryInUsecs();
             }
 
             const SortedVector< wp<Track> >& activeTracks = mActiveTracks;
@@ -1235,7 +1235,6 @@ bool AudioFlinger::MixerThread::threadLoop()
                     }
 
                     standbyTime = systemTime() + kStandbyTimeInNsecs;
-                    sleepTime = 0;
                     continue;
                 }
             }
@@ -1249,28 +1248,23 @@ bool AudioFlinger::MixerThread::threadLoop()
             sleepTime = 0;
             standbyTime = systemTime() + kStandbyTimeInNsecs;
         } else {
-            sleepTime += kBufferRecoveryInUsecs;
-            if (sleepTime > kMaxBufferRecoveryInUsecs) {
-                sleepTime = kMaxBufferRecoveryInUsecs;
-            }
-            // There was nothing to mix this round, which means all
-            // active tracks were late. Sleep a little bit to give
-            // them another chance. If we're too late, write 0s to audio
-            // hardware to avoid underrun.
-            if (mBytesWritten != 0 && sleepTime >= kMaxBufferRecoveryInUsecs) {
+            // If no tracks are ready, sleep once for the duration of an output
+            // buffer size, then write 0s to the output
+            if (sleepTime == 0) {
+                sleepTime = maxBufferRecoveryInUsecs;
+            } else if (mBytesWritten != 0) {
                 memset (curBuf, 0, mixBufferSize);
                 sleepTime = 0;
             }
         }
 
         if (mSuspended) {
-            sleepTime = kMaxBufferRecoveryInUsecs;
+            sleepTime = maxBufferRecoveryInUsecs;
         }
         // sleepTime == 0 means we must write to audio hardware
         if (sleepTime == 0) {
             mLastWriteTime = systemTime();
             mInWrite = true;
-            LOGV("mOutput->write() thread %p frames %d", this, mFrameCount);
             int bytesWritten = (int)mOutput->write(curBuf, mixBufferSize);
             if (bytesWritten > 0) mBytesWritten += bytesWritten;
             mNumWrites++;
@@ -1393,7 +1387,7 @@ size_t AudioFlinger::MixerThread::prepareTracks_l(const SortedVector< wp<Track>
                 // No buffers for this track. Give it a few chances to
                 // fill a buffer, then remove it from active list.
                 if (--(track->mRetryCount) <= 0) {
-                    LOGV("BUFFER TIMEOUT: remove(%d) from active list", track->name());
+                    LOGV("BUFFER TIMEOUT: remove(%d) from active list on thread %p", track->name(), this);
                     tracksToRemove->add(track);
                 }
                 // For tracks using static shared memory buffer, make sure that we have
@@ -1583,6 +1577,16 @@ status_t AudioFlinger::MixerThread::dumpInternals(int fd, const Vector<String16>
     return NO_ERROR;
 }
 
+uint32_t AudioFlinger::MixerThread::getMaxBufferRecoveryInUsecs()
+{
+    uint32_t time = ((mFrameCount * 1000) / mSampleRate) * 1000;
+    // Add some margin with regard to scheduling precision
+    if (time > 10000) {
+        time -= 10000;
+    }
+    return time;
+}
+
 // ----------------------------------------------------------------------------
 AudioFlinger::DirectOutputThread::DirectOutputThread(const sp<AudioFlinger>& audioFlinger, AudioStreamOut* output)
     :   PlaybackThread(audioFlinger, output),
@@ -1598,7 +1602,8 @@ AudioFlinger::DirectOutputThread::~DirectOutputThread()
 
 bool AudioFlinger::DirectOutputThread::threadLoop()
 {
-    unsigned long sleepTime = 0;
+    uint32_t sleepTime = 0;
+    uint32_t maxBufferRecoveryInUsecs = getMaxBufferRecoveryInUsecs();
     sp<Track> trackToRemove;
     sp<Track> activeTrack;
     nsecs_t standbyTime = systemTime();
@@ -1615,6 +1620,7 @@ bool AudioFlinger::DirectOutputThread::threadLoop()
 
             if (checkForNewParameters_l()) {
                 mixBufferSize = mFrameCount*mFrameSize;
+                maxBufferRecoveryInUsecs = getMaxBufferRecoveryInUsecs();
             }
 
             // put audio hardware into standby after short delay
@@ -1648,7 +1654,6 @@ bool AudioFlinger::DirectOutputThread::threadLoop()
                     }
 
                     standbyTime = systemTime() + kStandbyTimeInNsecs;
-                    sleepTime = 0;
                     continue;
                 }
             }
@@ -1761,23 +1766,16 @@ bool AudioFlinger::DirectOutputThread::threadLoop()
             sleepTime = 0;
             standbyTime = systemTime() + kStandbyTimeInNsecs;
         } else {
-            sleepTime += kBufferRecoveryInUsecs;
-            if (sleepTime > kMaxBufferRecoveryInUsecs) {
-                sleepTime = kMaxBufferRecoveryInUsecs;
-            }
-            // There was nothing to mix this round, which means all
-            // active tracks were late. Sleep a little bit to give
-            // them another chance. If we're too late, write 0s to audio
-            // hardware to avoid underrun.
-            if (mBytesWritten != 0 && sleepTime >= kMaxBufferRecoveryInUsecs &&
-                AudioSystem::isLinearPCM(mFormat)) {
+            if (sleepTime == 0) {
+                sleepTime = maxBufferRecoveryInUsecs;
+            } else if (mBytesWritten != 0 && AudioSystem::isLinearPCM(mFormat)) {
                 memset (mMixBuffer, 0, mFrameCount * mFrameSize);
                 sleepTime = 0;
             }
         }
 
         if (mSuspended) {
-            sleepTime = kMaxBufferRecoveryInUsecs;
+            sleepTime = maxBufferRecoveryInUsecs;
         }
         // sleepTime == 0 means we must write to audio hardware
         if (sleepTime == 0) {
@@ -1861,6 +1859,21 @@ bool AudioFlinger::DirectOutputThread::checkForNewParameters_l()
     return reconfig;
 }
 
+uint32_t AudioFlinger::DirectOutputThread::getMaxBufferRecoveryInUsecs()
+{
+    uint32_t time;
+    if (AudioSystem::isLinearPCM(mFormat)) {
+        time = ((mFrameCount * 1000) / mSampleRate) * 1000;
+        // Add some margin with regard to scheduling precision
+        if (time > 10000) {
+            time -= 10000;
+        }
+    } else {
+        time = 10000;
+    }
+    return time;
+}
+
 // ----------------------------------------------------------------------------
 
 AudioFlinger::DuplicatingThread::DuplicatingThread(const sp<AudioFlinger>& audioFlinger, AudioFlinger::MixerThread* mainThread)
@@ -1877,13 +1890,15 @@ AudioFlinger::DuplicatingThread::~DuplicatingThread()
 
 bool AudioFlinger::DuplicatingThread::threadLoop()
 {
-    unsigned long sleepTime = kBufferRecoveryInUsecs;
+    uint32_t sleepTime = 0;
+    uint32_t maxBufferRecoveryInUsecs = getMaxBufferRecoveryInUsecs();
     int16_t* curBuf = mMixBuffer;
     Vector< sp<Track> > tracksToRemove;
     size_t enabledTracks = 0;
     nsecs_t standbyTime = systemTime();
     size_t mixBufferSize = mFrameCount*mFrameSize;
     SortedVector< sp<OutputTrack> > outputTracks;
+    uint32_t writeFrames = 0;
 
     while (!exitPending())
     {
@@ -1896,6 +1911,7 @@ bool AudioFlinger::DuplicatingThread::threadLoop()
 
             if (checkForNewParameters_l()) {
                 mixBufferSize = mFrameCount*mFrameSize;
+                maxBufferRecoveryInUsecs = getMaxBufferRecoveryInUsecs();
             }
 
             const SortedVector< wp<Track> >& activeTracks = mActiveTracks;
@@ -1935,7 +1951,6 @@ bool AudioFlinger::DuplicatingThread::threadLoop()
                     }
 
                     standbyTime = systemTime() + kStandbyTimeInNsecs;
-                    sleepTime = kBufferRecoveryInUsecs;
                     continue;
                 }
             }
@@ -1947,29 +1962,30 @@ bool AudioFlinger::DuplicatingThread::threadLoop()
             // mix buffers...
             mAudioMixer->process(curBuf);
             sleepTime = 0;
-            standbyTime = systemTime() + kStandbyTimeInNsecs;
+            writeFrames = mFrameCount;
         } else {
-            sleepTime += kBufferRecoveryInUsecs;
-            if (sleepTime > kMaxBufferRecoveryInUsecs) {
-                sleepTime = kMaxBufferRecoveryInUsecs;
-            }
-            // There was nothing to mix this round, which means all
-            // active tracks were late. Sleep a little bit to give
-            // them another chance. If we're too late, write 0s to audio
-            // hardware to avoid underrun.
-            if (mBytesWritten != 0 && sleepTime >= kMaxBufferRecoveryInUsecs) {
-                memset (curBuf, 0, mixBufferSize);
-                sleepTime = 0;
+            if (sleepTime == 0) {
+                sleepTime = maxBufferRecoveryInUsecs;
+            } else if (mBytesWritten != 0) {
+                // flush remaining overflow buffers in output tracks
+                for (size_t i = 0; i < outputTracks.size(); i++) {
+                    if (outputTracks[i]->isActive()) {
+                        sleepTime = 0;
+                        writeFrames = 0;
+                        break;
+                    }
+                }
             }
         }
 
         if (mSuspended) {
-            sleepTime = kMaxBufferRecoveryInUsecs;
+            sleepTime = maxBufferRecoveryInUsecs;
         }
         // sleepTime == 0 means we must write to audio hardware
         if (sleepTime == 0) {
+            standbyTime = systemTime() + kStandbyTimeInNsecs;
             for (size_t i = 0; i < outputTracks.size(); i++) {
-                outputTracks[i]->write(curBuf, mFrameCount);
+                outputTracks[i]->write(curBuf, writeFrames);
             }
             mStandby = false;
             mBytesWritten += mixBufferSize;
@@ -2026,7 +2042,6 @@ void AudioFlinger::DuplicatingThread::removeOutputTrack(MixerThread *thread)
     LOGV("removeOutputTrack(): unkonwn thread: %p", thread);
 }
 
-
 // ----------------------------------------------------------------------------
 
 // TrackBase constructor must be called with AudioFlinger::mLock held
@@ -2300,7 +2315,7 @@ status_t AudioFlinger::PlaybackThread::Track::getNextBuffer(AudioBufferProvider:
 getNextBuffer_exit:
      buffer->raw = 0;
      buffer->frameCount = 0;
-     LOGV("getNextBuffer() no more data");
+     LOGV("getNextBuffer() no more data for track %d on thread %p", mName, mThread.unsafe_get());
      return NOT_ENOUGH_DATA;
 }
 
@@ -2341,7 +2356,7 @@ void AudioFlinger::PlaybackThread::Track::stop()
             if (playbackThread->mActiveTracks.indexOf(this) < 0) {
                 reset();
             }
-            LOGV("(> STOPPED) => STOPPED (%d)", mName);
+            LOGV("(> STOPPED) => STOPPED (%d) on thread %p", mName, playbackThread);
         }
     }
 }
@@ -2354,7 +2369,7 @@ void AudioFlinger::PlaybackThread::Track::pause()
         Mutex::Autolock _l(thread->mLock);
         if (mState == ACTIVE || mState == RESUMING) {
             mState = PAUSING;
-            LOGV("ACTIVE/RESUMING => PAUSING (%d)", mName);
+            LOGV("ACTIVE/RESUMING => PAUSING (%d) on thread %p", mName, thread.get());
         }
     }
 }
@@ -2566,7 +2581,7 @@ bool AudioFlinger::PlaybackThread::OutputTrack::write(int16_t* data, uint32_t fr
 
     uint32_t waitTimeLeftMs = mWaitTimeMs;
 
-    if (!mActive) {
+    if (!mActive && frames != 0) {
         start();
         sp<ThreadBase> thread = mThread.promote();
         if (thread != 0) {
@@ -2608,7 +2623,7 @@ bool AudioFlinger::PlaybackThread::OutputTrack::write(int16_t* data, uint32_t fr
                 break;
             }
             uint32_t waitTimeMs = (uint32_t)ns2ms(systemTime() - startTime);
-//            LOGV("OutputTrack::write() waitTimeMs %d waitTimeLeftMs %d", waitTimeMs, waitTimeLeftMs)
+            LOGV("OutputTrack::write() to thread %p waitTimeMs %d waitTimeLeftMs %d", mThread.unsafe_get(), waitTimeMs, waitTimeLeftMs);
             if (waitTimeLeftMs >= waitTimeMs) {
                 waitTimeLeftMs -= waitTimeMs;
             } else {
@@ -2663,7 +2678,7 @@ bool AudioFlinger::PlaybackThread::OutputTrack::write(int16_t* data, uint32_t fr
             pInBuffer->i16 = pInBuffer->mBuffer;
             memset(pInBuffer->raw, 0, frames * channels * sizeof(int16_t));
             mBufferQueue.add(pInBuffer);
-        } else {
+        } else if (mActive) {
             stop();
         }
     }
diff --git a/libs/audioflinger/AudioFlinger.h b/libs/audioflinger/AudioFlinger.h
index 3699019..4bf73ce 100644
--- a/libs/audioflinger/AudioFlinger.h
+++ b/libs/audioflinger/AudioFlinger.h
@@ -524,6 +524,10 @@ private:
         bool                            mMasterMute;
         SortedVector< wp<Track> >       mActiveTracks;
 
+        virtual int             getTrackName_l() = 0;
+        virtual void            deleteTrackName_l(int name) = 0;
+        virtual uint32_t        getMaxBufferRecoveryInUsecs() = 0;
+
     private:
 
         friend class AudioFlinger;
@@ -539,8 +543,7 @@ private:
 
         status_t    addTrack_l(const sp<Track>& track);
         void        destroyTrack_l(const sp<Track>& track);
-        virtual int         getTrackName_l() = 0;
-        virtual void        deleteTrackName_l(int name) = 0;
+
         void        readOutputParameters();
 
         virtual status_t    dumpInternals(int fd, const Vector<String16>& args);
@@ -571,13 +574,14 @@ private:
                                       int streamType);
                     void        putTracks(SortedVector < sp<Track> >& tracks,
                                       SortedVector < wp<Track> >& activeTracks);
-        virtual     int         getTrackName_l();
-        virtual     void        deleteTrackName_l(int name);
         virtual     bool        checkForNewParameters_l();
         virtual     status_t    dumpInternals(int fd, const Vector<String16>& args);
 
     protected:
         size_t prepareTracks_l(const SortedVector< wp<Track> >& activeTracks, Vector< sp<Track> > *tracksToRemove);
+        virtual     int         getTrackName_l();
+        virtual     void        deleteTrackName_l(int name);
+        virtual     uint32_t    getMaxBufferRecoveryInUsecs();
 
         AudioMixer*                     mAudioMixer;
     };
@@ -591,9 +595,12 @@ private:
         // Thread virtuals
         virtual     bool        threadLoop();
 
+        virtual     bool        checkForNewParameters_l();
+
+    protected:
         virtual     int         getTrackName_l();
         virtual     void        deleteTrackName_l(int name);
-        virtual     bool        checkForNewParameters_l();
+        virtual     uint32_t    getMaxBufferRecoveryInUsecs();
 
     private:
         float mLeftVolume;