AndroidでAudioTrackを使ってPCMファイルを鳴らす。

assetsフォルダに置いた16Bit StereoのリニアPCMファイルを鳴らすコード的なもの。

class PlayThread extends Thread {
    byte[] pcmData;
    AudioTrack audioTrack;
    float maxVolume ;
    float minVolume;
    PlayThread(String filename) {
        setPcmData(filename);
        makeAudioTrack();
        maxVolume = AudioTrack.getMaxVolume();
        minVolume = AudioTrack.getMinVolume();
    }
    public void run() {
        if (audioTrack != null) {
            int result= audioTrack.setLoopPoints(0, pcmData.length/4, -1);
            if (result != AudioTrack.SUCCESS) {
                System.out.println("result="+result+"pcmData.length="+ pcmData.length);
            }
            audioTrack.write(pcmData, 0, pcmData.length);
            audioTrack.play();
        }

    }
    void makeAudioTrack() {

        audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                44100, AudioFormat.CHANNEL_CONFIGURATION_STEREO,
                AudioFormat.ENCODING_PCM_16BIT, pcmData.length,
                AudioTrack.MODE_STATIC);
    }

    void playStop() {
        if (audioTrack.getPlayState() == AudioTrack.PLAYSTATE_PLAYING) {
            audioTrack.stop();
            audioTrack.release();
        }
    }
    void setStereoVolume(int left,int right) {
        float leftF = minVolume+(maxVolume-minVolume)*left/100;
        float rightF = minVolume+(maxVolume-minVolume)*right/100;
        audioTrack.setStereoVolume(leftF, rightF);
    }
    void setPcmData(String s) {
        AssetManager as = getResources().getAssets();
        AssetFileDescriptor afd = null;

        try {
            afd = as.openFd (s);
        } catch (IOException e) {
            e.printStackTrace();
        }

        if (afd != null) {
            pcmData = new byte[(int)afd.getLength()];
            InputStream is = null;
            try {
                is = afd.createInputStream();
                is.read(pcmData);
            } catch (IOException e) {
                e.printStackTrace();
            }finally {
                IOUtils.closeQuietly(is);
            }
        }else {

            finish();
        }
    }
}

}