将PCM记录的数据写入.wav文件（java android）

I'm using AudioRecord to record 16 bit PCM data in android. After recording the data and saving it to a file, I read it back to save it as .wav file.

我正在使用AudioRecord在android中记录16位PCM数据。在记录数据并将其保存到文件后，我将其读回以将其另存为.wav文件。

The problem is that the WAV files are recognized by media players but play nothing but pure noise. My best guess at the moment is that my wav file headers are incorrect but I have been unable to see what exactly the problem is. (I think this because I can play the raw PCM data that I recorded in Audacity)

问题是媒体播放器识别WAV文件，但只播放纯噪音。我现在最好的猜测是我的wav文件头不正确，但我一直无法确定问题到底是什么。 （我想这是因为我可以播放我在Audacity录制的原始PCM数据）

Here's my code for reading the raw PCM file and saving it as a .wav:

这是我的代码，用于读取原始PCM文件并将其保存为.wav：

private void properWAV(File fileToConvert, float newRecordingID){
    try {
        long mySubChunk1Size = 16;
        int myBitsPerSample= 16;
        int myFormat = 1;
        long myChannels = 1;
        long mySampleRate = 22100;
        long myByteRate = mySampleRate * myChannels * myBitsPerSample/8;
        int myBlockAlign = (int) (myChannels * myBitsPerSample/8);

        byte[] clipData = getBytesFromFile(fileToConvert);

        long myDataSize = clipData.length;
        long myChunk2Size =  myDataSize * myChannels * myBitsPerSample/8;
        long myChunkSize = 36 + myChunk2Size;

        OutputStream os;        
        os = new FileOutputStream(new File("/sdcard/onefile/assessor/OneFile_Audio_"+ newRecordingID+".wav"));
        BufferedOutputStream bos = new BufferedOutputStream(os);
        DataOutputStream outFile = new DataOutputStream(bos);

        outFile.writeBytes("RIFF");                                 // 00 - RIFF
        outFile.write(intToByteArray((int)myChunkSize), 0, 4);      // 04 - how big is the rest of this file?
        outFile.writeBytes("WAVE");                                 // 08 - WAVE
        outFile.writeBytes("fmt ");                                 // 12 - fmt 
        outFile.write(intToByteArray((int)mySubChunk1Size), 0, 4);  // 16 - size of this chunk
        outFile.write(shortToByteArray((short)myFormat), 0, 2);     // 20 - what is the audio format? 1 for PCM = Pulse Code Modulation
        outFile.write(shortToByteArray((short)myChannels), 0, 2);   // 22 - mono or stereo? 1 or 2?  (or 5 or ???)
        outFile.write(intToByteArray((int)mySampleRate), 0, 4);     // 24 - samples per second (numbers per second)
        outFile.write(intToByteArray((int)myByteRate), 0, 4);       // 28 - bytes per second
        outFile.write(shortToByteArray((short)myBlockAlign), 0, 2); // 32 - # of bytes in one sample, for all channels
        outFile.write(shortToByteArray((short)myBitsPerSample), 0, 2);  // 34 - how many bits in a sample(number)?  usually 16 or 24
        outFile.writeBytes("data");                                 // 36 - data
        outFile.write(intToByteArray((int)myDataSize), 0, 4);       // 40 - how big is this data chunk
        outFile.write(clipData);                                    // 44 - the actual data itself - just a long string of numbers

        outFile.flush();
        outFile.close();

    } catch (IOException e) {
        e.printStackTrace();
    }

}


private static byte[] intToByteArray(int i)
    {
        byte[] b = new byte[4];
        b[0] = (byte) (i & 0x00FF);
        b[1] = (byte) ((i >> 8) & 0x000000FF);
        b[2] = (byte) ((i >> 16) & 0x000000FF);
        b[3] = (byte) ((i >> 24) & 0x000000FF);
        return b;
    }

    // convert a short to a byte array
    public static byte[] shortToByteArray(short data)
    {
        /*
         * NB have also tried:
         * return new byte[]{(byte)(data & 0xff),(byte)((data >> 8) & 0xff)};
         * 
         */

        return new byte[]{(byte)(data & 0xff),(byte)((data >>> 8) & 0xff)};
    }

I haven't included getBytesFromFile() since it takes up too much space and its a tried and tested method. Anyway, here's the code that does the actual recording:

我没有包含getBytesFromFile（），因为它占用了太多的空间，并且是一个久经考验的方法。无论如何，这是执行实际录制的代码：

public void run() { 
    Log.i("ONEFILE", "Starting main audio capture loop...");

    int frequency = 22100;
    int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;
    int audioEncoding = AudioFormat.ENCODING_PCM_16BIT; 

    final int bufferSize = AudioRecord.getMinBufferSize(frequency, channelConfiguration, audioEncoding); 

    AudioRecord audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, frequency, channelConfiguration, audioEncoding, bufferSize);

    audioRecord.startRecording();
    ByteArrayOutputStream recData = new ByteArrayOutputStream(); 
    DataOutputStream dos = new DataOutputStream(recData);

    short[] buffer = new short[bufferSize];  
    audioRecord.startRecording();

    while (!stopped) {  
        int bufferReadResult = audioRecord.read(buffer, 0, bufferSize);

        for(int i = 0; i < bufferReadResult;i++) {
            try {
                dos.writeShort(buffer[i]);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }  
    audioRecord.stop();
    try {
        dos.flush();
        dos.close();
    } catch (IOException e1) {
        e1.printStackTrace();
    }

    audioRecord.stop();

    byte[] clipData = recData.toByteArray();

    File file = new File(audioOutputPath);
    if(file.exists())
        file.delete();
    file = new File(audioOutputPath);
    OutputStream os;
    try {
        os = new FileOutputStream(file);

        BufferedOutputStream bos = new BufferedOutputStream(os);
        DataOutputStream outFile = new DataOutputStream(bos);

        outFile.write(clipData);  

        outFile.flush();
        outFile.close();

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

Please suggest what could be going wrong.

请提出可能出现的问题。

4 个解决方案

#1

I've been wrestling with this exact same question for hours now, and my issue was mostly that when recording in 16 bits you have to be very careful about what you write to the output. The WAV file expects the data in Little Endian format, but using writeShort writes it to the output as Big Endian. I also got interesting results when using the other functions so I returned to writing bytes in the correct order and that works.

我几个小时以来一直在努力解决这个完全相同的问题，我的问题主要在于当以16位录制时你必须非常小心你写入输出的内容。 WAV文件需要Little Endian格式的数据，但使用writeShort将其作为Big Endian写入输出。当使用其他函数时，我也得到了有趣的结果，所以我返回以正确的顺序写字节，这是有效的。

I used a Hex editor extensively while debugging this. I can recommend you do the same. Also, the header in the answer above works, I used it to check versus my own code and this header is rather foolproof.

我在调试时广泛使用了Hex编辑器。我可以建议你这样做。此外，上面的答案中的标题工作，我用它来检查我自己的代码，这个标题是相当万无一失的。

#2

As per the header is concern, I had followed this code (if it's helps you some way).

根据标题是关注，我已经遵循这个代码（如果它对你有所帮助）。

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);

#3

Are you certain of the byte order? "RIFF", "WAV", "fmt", and "data" look fine but the numbers in the header may need to be a different order (little endian vs. big endian). You also don't need to convert to bytes manually using your intToByteArray method. You could use the writeInt and writeShort methods of DataOutputStream. For the first one, this would look something like:

你确定字节顺序吗？ “RIFF”，“WAV”，“fmt”和“数据”看起来很好，但标题中的数字可能需要是不同的顺序（小端与大端）。您也不需要使用intToByteArray方法手动转换为字节。您可以使用DataOutputStream的writeInt和writeShort方法。对于第一个，这看起来像：

outFile.writeInt(Integer.reverseBytes((int)myChunkSize));

outFile.writeInt（Integer.reverseBytes（（int）的myChunkSize））;

For the shorts it'd be like:

对于短裤来说就像：

outFile.writeShort(Short.reverseBytes((short)myFormat))

outFile.writeShort（Short.reverseBytes（（短）myFormat））

This way you also don't need to provide the offset and length (0, 4) numbers. It's nice.

这样您也不需要提供偏移量和长度（0,4）数字。这真好。

#4

As Ronald Kunenborg correctly states the problem is the Litte Endian / Big Endian conversion.

正如Ronald Kunenborg正确地指出问题是Litte Endian / Big Endian转换。

The simplest way is to write a short helper like this:

最简单的方法是编写一个这样的简短助手：

public static void writeShortLE(DataOutputStream out, short value) {
  out.writeByte(value & 0xFF);
  out.writeByte((value >> 8) & 0xFF);
}

This is very helpful if you record audio to a wave file with Android and you're in need of the short array, too.

如果您使用Android将音频录制到wave文件并且您也需要短阵列，这将非常有用。

(Credits: https://*.com/a/1394839/1686216)

（学分：https：//*.com/a/1394839/1686216）