Android的AudioTrack播放.wav文件，只得到白噪声 [英] Android AudioTrack playing .wav file, getting only white noise

问题描述

当我播放文件具有以下code：

When I play a file with the following code:

private void PlayAudioFileViaAudioTrack(int ResId) throws IOException {

    int intSize = android.media.AudioTrack.getMinBufferSize(11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT);

    AudioTrack at = new AudioTrack(AudioManager.STREAM_MUSIC, 11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, intSize,
            AudioTrack.MODE_STREAM);

    int count = 256 * 1024; // 256 kb
    byte[] byteData = null;
    byteData = new byte[(int) count];
    InputStream in = null;
    AssetFileDescriptor fd = null;
    fd = mResources.openRawResourceFd(ResId);
    in = mResources.openRawResource(ResId);

    int bytesRead = 0, amount = 0;
    int size = (int) fd.getLength();
    at.play();
    while (bytesRead < size) {
        amount = in.read(byteData, 0, count);
        if (amount != -1) {
            at.write(byteData, 0, amount);
        }
    }
    in.close();
    at.stop();
    at.release();

}

我听到的唯一的事情是静态的，白噪声。我检查了我的.wav文件具有相同的属性（采样率，比特率）。我没有关于原始音频数据（PCM）多的知识，所以我想知道如果任何人都可以看看有什么错我的code。

The only thing I hear is static, white noise. I've checked that my .wav file has the same properties (samplerate,bitrate). I don't have to much knowledge about raw audio data(PCM), so I was wondering if anyone could see what's wrong with my code.

推荐答案

可以看到，刚刚从wav文件中读取数据，只是将它们导入到AudioTrack。 WAV文件带有一个小头，你可以在这里看到<一href="https://ccrma.stanford.edu/courses/422/projects/WaveFormat/">https://ccrma.stanford.edu/courses/422/projects/WaveFormat/所以，你必须跳过头，并在正确的地方，实际的音频数据指向您的文件描述符。

from your code i can see that you just read data from the wav file and just import them to the AudioTrack. Wav files have a small header as you can see here https://ccrma.stanford.edu/courses/422/projects/WaveFormat/ So you have to skip the header and point your file descriptor at the right place where the actual audio data are.

此外，当您播放音频文件，你正在处理的字节操作，你应该把字节序的照顾。看看这里<一href="http://stackoverflow.com/questions/3925030/using-audiotrack-in-android-to-play-a-wav-file">Using AudioTrack在Android的播放WAV文件

Also when you playing an audio file and you are dealing with byte operations you should take care of the Endianess. Take a look here Using AudioTrack in Android to play a WAV file

下面我code（一些检查和WAV头跳跃缺少），在这两个的Nexus One和Galaxy S的工作与频率8000Hz的16位编码WAV文件。

Below my code (some checks and the WAV header skip are missing) that works in both Nexus One and Galaxy S with a wav file with frequency 8000Hz and 16 bit encoding.

public void playWav(){
    int minBufferSize = AudioTrack.getMinBufferSize(8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT);
    int bufferSize = 512;
    AudioTrack at = new AudioTrack(AudioManager.STREAM_MUSIC, 8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, minBufferSize, AudioTrack.MODE_STREAM);
    String filepath = Environment.getExternalStorageDirectory().getAbsolutePath();

    int i = 0;
    byte[] s = new byte[bufferSize];
    try {
        FileInputStream fin = new FileInputStream(filepath + "/REFERENCE.wav");
        DataInputStream dis = new DataInputStream(fin);

        at.play();
        while((i = dis.read(s, 0, bufferSize)) > -1){
            at.write(s, 0, i);

        }
        at.stop();
        at.release();
        dis.close();
        fin.close();

    } catch (FileNotFoundException e) {
        // TODO
        e.printStackTrace();
    } catch (IOException e) {
        // TODO
        e.printStackTrace();
    }       
}

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