Android: Fix deadlock in AudioTrack processing

When exiting during a pause, there was an infinite wait for the
output thread to end if there was data buffered. Now fixed.

Refs #13446

mythtv/android-package-source/src/org/mythtv/audio/AudioOutputAudioTrack.java

@@ -26,6 +26,7 @@ public class AudioOutputAudioTrack
     int latencyCount;
     boolean isSettled;
     boolean isBufferInFlux;
+    boolean isOutputThreadStarted;
 
     public AudioOutputAudioTrack(int encoding, int sampleRate, int bufferSize, int channels)
     {
@@ -94,36 +95,34 @@ public int write(byte[] audioData, int sizeInBytes)
         int written = 0;
         int ret = 0;
         int i;
-        if (player != null)
+        while (buf.hasRemaining())
         {
-            while (buf.hasRemaining())
+            synchronized(syncBuffer)
             {
+                // get out if we should not be here
+                if (player == null || !isOutputThreadStarted)
+                    break;
                 ret = player.write(buf, buf.remaining(), AudioTrack.WRITE_NON_BLOCKING);
                 if (ret < 0)
                 {
                     break;
                 }
                 written += ret;
-                synchronized(syncBuffer)
-                {
-                    bytesWritten += ret;
-                    lastwritetime = System.nanoTime();
-                    // Note that only after this method returns is this data
-                    // removed from the caller's buffer.
-                    // bufferedBytes may be negative because actually some
-                    // data still in the "Audio circular buffer" may have
-                    // already played.
-                    bufferedBytes = buf.remaining() - sizeInBytes;
-                }
-                try
-                {
-                    Thread.sleep(10);
-                }
-                catch (InterruptedException ex) {}
+                bytesWritten += ret;
+                lastwritetime = System.nanoTime();
+                // Note that only after this method returns is this data
+                // removed from the caller's buffer.
+                // bufferedBytes may be negative because actually some
+                // data still in the "Audio circular buffer" may have
+                // already played.
+                bufferedBytes = buf.remaining() - sizeInBytes;
+            }
+            try
+            {
+                Thread.sleep(10);
             }
+            catch (InterruptedException ex) {}
         }
-        else
-            written = AudioTrack.ERROR;
         synchronized(syncBuffer)
         {
             // After we return to caller, the data will be removed from
@@ -216,9 +215,21 @@ public void pause (boolean doPause)
 
     public void release ()
     {
-        if (player != null)
+        if (player == null)
+            return;
+
+        synchronized(syncBuffer)
+        {
+            pause(true);
+            player.flush();
             player.release();
-        player = null;
+            player = null;
+        }
+    }
+
+    public void setOutputThread (boolean isStarted)
+    {
+        isOutputThreadStarted = isStarted;
     }
 
 }

mythtv/libs/libmyth/audio/audiooutputaudiotrack.cpp

@@ -56,7 +56,6 @@ AudioOutputAudioTrack::AudioOutputAudioTrack(const AudioSettings &settings) :
 AudioOutputAudioTrack::~AudioOutputAudioTrack()
 {
     KillAudio();
-    CloseDevice();
 }
 
 bool AudioOutputAudioTrack::OpenDevice()
@@ -295,3 +294,27 @@ void AudioOutputAudioTrack::SetSourceBitrate(int rate)
         }
     }
 }
+
+bool AudioOutputAudioTrack::StartOutputThread(void)
+{
+    QAndroidJniEnvironment env;
+    if (m_audioTrack)
+    {
+        m_audioTrack->callMethod<void>("setOutputThread","(Z)V",true);
+        ANDROID_EXCEPTION_CLEAR
+    }
+
+    return AudioOutputBase::StartOutputThread();
+}
+
+void AudioOutputAudioTrack::StopOutputThread(void)
+{
+    QAndroidJniEnvironment env;
+    if (m_audioTrack)
+    {
+        m_audioTrack->callMethod<void>("setOutputThread","(Z)V",false);
+        ANDROID_EXCEPTION_CLEAR
+    }
+
+    AudioOutputBase::StopOutputThread();
+}

mythtv/libs/libmyth/audio/audiooutputaudiotrack.h

@@ -35,6 +35,8 @@ class AudioOutputAudioTrack : public AudioOutputBase
     int  GetBufferedOnSoundcard(void) const override; // AudioOutputBase
     AudioOutputSettings* GetOutputSettings(bool digital) override; // AudioOutputBase
     void SetSourceBitrate(int rate) override; // AudioOutputBase
+    bool StartOutputThread(void) override; // AudioOutputBase
+    void StopOutputThread(void) override; // AudioOutputBase
     QAndroidJniObject *m_audioTrack {nullptr};
     int m_bitsPer10Frames {0};
 };