plectrum

AndroidAudioPlayer.java (5088B)

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 package be.tarsos.dsp.io.android;
 
 import android.media.AudioFormat;
 import android.media.AudioManager;
 import android.media.AudioTrack;
 import android.util.Log;
 
 import be.tarsos.dsp.AudioEvent;
 import be.tarsos.dsp.AudioProcessor;
 import be.tarsos.dsp.io.TarsosDSPAudioFloatConverter;
 import be.tarsos.dsp.io.TarsosDSPAudioFormat;
 
 /**
  * Plays audio from an {@link be.tarsos.dsp.AudioDispatcher} or {@link be.tarsos.dsp.AudioGenerator}
  * on an Android {@link AudioTrack}. This class only supports mono, 16 bit PCM. Depending on your device,
  * some sample rates could not be supported. This class uses the method that writes floats
  * to {@link android.media.AudioTrack} which is only introduced in Android API Level 21.
  *
  * @author Alex Mikhalev
  * @author Joren Six
  * @see AudioTrack
  */
 public class AndroidAudioPlayer implements AudioProcessor {
     /**
      * The default stream type to use.
      */
     public static final int DEFAULT_STREAM_TYPE = AudioManager.STREAM_MUSIC;
     private static final String TAG = "AndroidAudioPlayer";
 
     private final AudioTrack audioTrack;
 
 
     /**
      * Constructs a new AndroidAudioPlayer from an audio format, default buffer size and stream type.
      *
      * @param audioFormat The audio format of the stream that this AndroidAudioPlayer will process.
      *                    This can only be 1 channel, PCM 16 bit.
      * @param bufferSizeInSamples  The requested buffer size in samples.
      * @param streamType  The type of audio stream that the internal AudioTrack should use. For
      *                    example, {@link AudioManager#STREAM_MUSIC}.
      * @throws IllegalArgumentException if audioFormat is not valid or if the requested buffer size is invalid.
      * @see AudioTrack
      */
     public AndroidAudioPlayer(TarsosDSPAudioFormat audioFormat, int bufferSizeInSamples, int streamType) {
         if (audioFormat.getChannels() != 1) {
             throw new IllegalArgumentException("TarsosDSP only supports mono audio channel count: " + audioFormat.getChannels());
         }
 
         // The requested sample rate
         int sampleRate = (int) audioFormat.getSampleRate();
 
         //The buffer size in bytes is twice the buffer size expressed in samples if 16bit samples are used:
         int bufferSizeInBytes = bufferSizeInSamples * audioFormat.getSampleSizeInBits()/8;
 
         // From the Android API about getMinBufferSize():
         // The total size (in bytes) of the internal buffer where audio data is read from for playback.
         // If track's creation mode is MODE_STREAM, you can write data into this buffer in chunks less than or equal to this size,
         // and it is typical to use chunks of 1/2 of the total size to permit double-buffering. If the track's creation mode is MODE_STATIC,
         // this is the maximum length sample, or audio clip, that can be played by this instance. See getMinBufferSize(int, int, int) to determine
         // the minimum required buffer size for the successful creation of an AudioTrack instance in streaming mode. Using values smaller
         // than getMinBufferSize() will result in an initialization failure.
         int minBufferSizeInBytes = AudioTrack.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_OUT_MONO,  AudioFormat.ENCODING_PCM_16BIT);
         if(minBufferSizeInBytes > bufferSizeInBytes){
             throw new IllegalArgumentException("The buffer size should be at least " + (minBufferSizeInBytes/(audioFormat.getSampleSizeInBits()/8)) + " (samples) according to  AudioTrack.getMinBufferSize().");
         }
 
         //http://developer.android.com/reference/android/media/AudioTrack.html#AudioTrack(int, int, int, int, int, int)
         audioTrack = new AudioTrack(streamType, sampleRate, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, bufferSizeInBytes,AudioTrack.MODE_STREAM);
 
         audioTrack.play();
     }
 
     /**
      * Constructs a new AndroidAudioPlayer from an audio format.
      *
      * @param audioFormat The audio format that this AndroidAudioPlayer will process.
      * @see AndroidAudioPlayer#AndroidAudioPlayer(TarsosDSPAudioFormat, int, int)
      */
     public AndroidAudioPlayer(TarsosDSPAudioFormat audioFormat) {
         this(audioFormat, 4096, DEFAULT_STREAM_TYPE);
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean process(AudioEvent audioEvent) {
         int overlapInSamples = audioEvent.getOverlap();
         int stepSizeInSamples = audioEvent.getBufferSize() - overlapInSamples;
         byte[] byteBuffer = audioEvent.getByteBuffer();
 
         //int ret = audioTrack.write(audioEvent.getFloatBuffer(),overlapInSamples,stepSizeInSamples,AudioTrack.WRITE_BLOCKING);
         int ret = audioTrack.write(byteBuffer,overlapInSamples*2,stepSizeInSamples*2);
         if (ret < 0) {
             Log.e(TAG, "AudioTrack.write returned error code " + ret);
         }
         return true;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void processingFinished() {
         audioTrack.flush();
         audioTrack.stop();
         audioTrack.release();
     }
 }