java - Android:使录制的pcm原始数据可播放

Question

我正在开发一个Android应用程序，它支持音频录制，代码如下，示例可以在这里找到:

http://developer.samsung.com/technical-doc/view.do;jsessionid=tT01JrgM5DRC15pN56v20xzJXcDYv7hZVLvPhT0zJ4kfvSc1TlTM!-846162528?v=T000000090

变量:

   private static final int RECORDER_BPP = 16;
   private static final int RECORDER_SAMPLERATE = 22050;
   private static final int RECORDER_CHANNELS =       AudioFormat.CHANNEL_IN_MONO;
   private static final int RECORDER_CHANNELS_NUMBER = 1;
   private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
   private AudioRecord recorder = null;
   private short[] mBuffer;
   private int bufferSize = 0;
   private boolean IsRecording = false;

为 bufferSize 赋值:

 bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,
                    AudioFormat.CHANNEL_IN_MONO,
                    AudioFormat.ENCODING_PCM_16BIT);

创建记录器:

 recorder = new AudioRecord(source, RECORDER_SAMPLERATE, RECORDER_CHANNELS,RECORDER_AUDIO_ENCODING, bufferSize);

来源表示要使用的麦克风。

将接收到的内容存储在原始文件中:

    new Thread(new Runnable() {
    @Override
    public void run() {
    DataOutputStream output = null;
    try {
    output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(new File(getTempFilename()))));
    while (IsRecording) {
    int readSize = recorder.read(mBuffer, 0, mBuffer.length);
    for (int i = 0; i < readSize; i++) {
    output.writeShort(mBuffer[i]);
    } 
    }
    } catch (IOException e) {
    Toast.makeText(mContext, e.getMessage(), Toast.LENGTH_SHORT).show();
    } finally {
    if (output != null) {
    try {
    output.flush();
    } catch (IOException e) {
    Toast.makeText(mContext, e.getMessage(), Toast.LENGTH_SHORT).show();
    } finally { 
    try {
    output.close();
    } catch (IOException e) {
    Toast.makeText(mContext, e.getMessage(), Toast.LENGTH_SHORT).show();
    }
    }
    }
    }
    }
    }).start();   

我愿意:

1. 使用 android.media.MediaPlayer 播放录制的音频
2. 在另一项 Activity 中，将原始源编码为 mp3。

根据上面的页面，我可以编译 Lame 库并创建包装器。因此，这个原始文件可以毫无问题地编码为 mp3，但我找不到如何在编码之前使这个原始源可播放的方法。找到的为原始文件创建波头的解决方案不可用。

有人有解决办法吗？

更新: 为了创建标题，我尝试了以下方法: ...

in = new FileInputStream(inFilename);
                        totalAudioLen = in.getChannel().size();
                        totalDataLen = totalAudioLen + 36;
long longSampleRate = RECORDER_SAMPLERATE;
                int channels = 1;
                long byteRate = RECORDER_BPP * RECORDER_SAMPLERATE * channels/8;

...
WriteWaveFileHeader(输出，totalAudioLen，totalDataLen， longSampleRate、 channel 、byteRate);

private void WriteWaveFileHeader(
                        FileOutputStream out, long totalAudioLen,
                        long totalDataLen, long longSampleRate, int channels,
                        long byteRate) throws IOException {
                byte[] header = new byte[44];

                header[0] = 'R';  // RIFF/WAVE header
                header[1] = 'I';
                header[2] = 'F';
                header[3] = 'F';
                header[4] = (byte) (totalDataLen & 0xff);
                header[5] = (byte) ((totalDataLen >> 8) & 0xff);
                header[6] = (byte) ((totalDataLen >> 16) & 0xff);
                header[7] = (byte) ((totalDataLen >> 24) & 0xff);
                header[8] = 'W';
                header[9] = 'A';
                header[10] = 'V';
                header[11] = 'E';
                header[12] = 'f';  // 'fmt ' chunk
                header[13] = 'm';
                header[14] = 't';
                header[15] = ' ';
                header[16] = 16;  // 4 bytes: size of 'fmt ' chunk
                header[17] = 0;
                header[18] = 0;
                header[19] = 0;
                header[20] = 1;  // format = 1
                header[21] = 0;
                header[22] = (byte) channels;
                header[23] = 0;
                header[24] = (byte) (longSampleRate & 0xff);
                header[25] = (byte) ((longSampleRate >> 8) & 0xff);
                header[26] = (byte) ((longSampleRate >> 16) & 0xff);
                header[27] = (byte) ((longSampleRate >> 24) & 0xff);
                header[28] = (byte) (byteRate & 0xff);
                header[29] = (byte) ((byteRate >> 8) & 0xff);
                header[30] = (byte) ((byteRate >> 16) & 0xff);
                header[31] = (byte) ((byteRate >> 24) & 0xff);
                header[32] = (byte) (2 * 16 / 8);  // block align
                header[33] = 0;
                header[34] = RECORDER_BPP;  // bits per sample
                header[35] = 0;
                header[36] = 'd';
                header[37] = 'a';
                header[38] = 't';
                header[39] = 'a';
                header[40] = (byte) (totalAudioLen & 0xff);
                header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
                header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
                header[43] = (byte) ((totalAudioLen >> 24) & 0xff);

                out.write(header, 0, 44); 
        }

结果是一个有噪声的波形文件

谢谢

Answer 1

如果您收到嘈杂的 WAV，原因可能是 16 位样本的字节序有问题。尝试在写入时混合字节，如下所示:

int readSize = recorder.read(mBuffer, 0, mBuffer.length);
for (int i = 0; i < readSize; i++) {
    output.writeShort(((mBuffer[i] >> 8) & 255) | (mBuffer[i] << 8));
}