I'm in the process of wring a music player that can play SID tracks (music from the Commodore 64), and everything is progressing nicely, except that I sometimes get audio stuttering. The stuttering only happens when the player is in the background, and another application has focus. It's most noticeable when a cpu heavy app (like Google Earth) is running in the foreground.
I have tried adjusting the priority of my thread and increasing the AudioTrack buffer size, but nothing has solved the stuttering problem. I believe the problem is that generating the audio takes quite a lot of cycles (I'm at 15-30% cpu load), and that my audio thread is being starved and cant keep up with AudioTrack's constant need for data. I'm must be doing something wrong, I can't imagine that gui threads should be able to starve a high priority audio thread. I hope someone have some ideas on how to get my player stutter free, as I'm at a loss :) This is a small test function that kinda emulates what I'm doing, and also have the same stuttering problem: (full test project at http://github.com/jhansen/android_test_audio_stutter ) private void play() { if(m_thread == null) { m_thread = new Thread(new Runnable() { public void run() { m_wakeLock.acquire(); Process.setThreadPriority(Process.THREAD_PRIORITY_AUDIO); int minBufferSize = AudioTrack.getMinBufferSize(44100, AudioFormat.ENCODING_PCM_16BIT, AudioFormat.CHANNEL_CONFIGURATION_MONO); AudioTrack audio = new AudioTrack(AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_CONFIGURATION_MONO , AudioFormat.ENCODING_PCM_16BIT, minBufferSize*4, AudioTrack.MODE_STREAM); audio.play(); // generate sinus tone short[] audioBuffer = new short[1024]; for(int i=0; i<audioBuffer.length; i++) audioBuffer[i] = (short)(Math.sin(i*Math.PI/audioBuffer.length*64)*32765.0f); long sleepDuration = audioBuffer.length*1000000000l/44100/3; // find out how many cyces to waste to spend around 1/3 of the total avilable time between AudioTrack writes // to increase the change of getting at least one uninterrupted run, run the profile a few times: int loopsPerBuffer = 0; for(int j=0; j<10; j++) { long profileStart = System.nanoTime(); for(int i=0; i<1000; i++) m_dummy += i; // to prevent the compiler from removing the loop long profileDuration = System.nanoTime()-profileStart; if(loopsPerBuffer==0 || sleepDuration/profileDuration<loopsPerBuffer) loopsPerBuffer = (int)(sleepDuration/profileDuration); } Log.v("StutterTest", "loopsPerBuffer:"+loopsPerBuffer); while(!Thread.interrupted()) { // to simulate expensive audio processing, burn about 1/3 of the cycles between writes: for(int j=0; j<loopsPerBuffer; j++) { for(int i=0; i<1000; i++) m_dummy += i; } audio.write(audioBuffer, 0, audioBuffer.length); } audio.stop(); audio.release(); m_wakeLock.release(); } }); m_thread.start(); } } -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en To unsubscribe, reply using "remove me" as the subject.
