CODEWITHSUNDEEP
javaandroidaudioaudiotrack
user833970
user833970

Reputation: 2799

AudioTrack not playing the full buffer

I am trying to play 10s of sound at 600hz but instead I get 600hz for no more then 3 sec. Can someone point out what I'm doing wrong?

    int minBuffersize = AudioTrack.getMinBufferSize(samplerate, 
           AudioFormat.CHANNEL_OUT_MONO,
            AudioFormat.ENCODING_PCM_16BIT);

    int size= (int) ((10f*samplerate)
            /minBuffersize +1);

            size*=minBuffersize;//round to the nearest minBuffersize multiple so I don't get an error

    short[] play= new short[size];

    for(int i =0;i<play.length;i++){
        float time=(float)i/(float)samplerate;

        play[i]=(short) (((float)Short.MAX_VALUE/10f)*Math.sin(
                600f
                *time
                *(2f*Math.PI)));
    }

    AudioTrack at = new AudioTrack(AudioManager.STREAM_MUSIC,
            samplerate,
            AudioFormat.CHANNEL_OUT_MONO,
            AudioFormat.ENCODING_PCM_16BIT,
            play.length,
            AudioTrack.MODE_STATIC);


    int result=at.write(play,0,play.length);

    Log.d("!!!", "result: "+result);

    at.play();

where the debug line returns 

result: 221184

consistently.

note that play.length = 442368.

after some more experimenting the buffer is always half of play.length, but the sound itself only last 3-5 sec, regardless of how big the buffer is.

Upvotes: 2

Views: 2945

Answers (3)

Enric Mieza
Enric Mieza

Reputation: 342

In the AudioTrack you're using AudioTrack.MODE_STATIC (for short sounds with low-latency requirements) while you should use AudioTrack.MODE_STREAM because it's the right one for long buffers (don't know exactly but is probably related with than 3 seconds).

Take a look here : AudioTrack

Just change your code to:

AudioTrack at = new AudioTrack(AudioManager.STREAM_MUSIC,
        samplerate,
        AudioFormat.CHANNEL_OUT_MONO,
        AudioFormat.ENCODING_PCM_16BIT,
        play.length,
        AudioTrack.MODE_STREAM);

And it should work.

Upvotes: 1

gleroyDroid
gleroyDroid

Reputation: 449

AudioTrack needs the buffer size in bytes. As a Short uses 2 bytes you should use size * 2 for your buffer size.

Upvotes: 1

Douglas Jones
Douglas Jones

Reputation: 2542

I would suggest decoupling the play length from the AudioTrack buffer size. In my experience it works well to just use the min buffer size and then let the large write block until it is completed.

Something else I've noticed that may be impacting this is that audio doesn't play until half of the buffer is filled. It may be possible with a buffer so large in the AudioTrack that it is just taking that half and trying to work through it.

Upvotes: 1

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