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android - 将录音编码和解码为 G711 ( PCMU - uLaw) 格式

转载 作者：塔克拉玛干 更新时间：2023-11-02 18:50:48 26 4
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当我们需要流式传输音频时，没有太多关于应用此编解码器的信息。在不应用编解码器的情况下，我的代码就像在两个设备之间建立通信的魅力一样工作，但我需要以该格式进行编码/解码，因为我需要使用服务器而不是在两个设备之间进行流式传输(我正在使用 2 个设备测试此代码)。

如果你们中的任何人能看到我的问题的关键在哪里，我正在寻找机会。我尝试了输入参数的不同配置。也许，我使用的编解码器是错误的(我从一个具有 Apache 许可证的项目中获取了它们。)

此值在记录器发送器中设置，就像在播放器接收器设备中一样:

private int port=50005;
private int sampleRate = 8000 ;//44100;
private int channelConfig = AudioFormat.CHANNEL_OUT_MONO;    
private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;       
int minBufSize = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat);

注意:播放器中的 CHANNEL_OUT_MONO 和录音器项中的 CHANNEL_IN_MONO。

这些是我的方法:

public void startStreamingEncoding() {

    Thread streamThread = new Thread(new Runnable() {

        @Override
        public void run() {
            try {

                android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

                DatagramSocket socket = new DatagramSocket();

                short[] buffer = new short[minBufSize];

                DatagramPacket packet;

                final InetAddress destination = InetAddress.getByName(ip_receiver); 

                recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,sampleRate,channelConfig,audioFormat,minBufSize*10);

                recorder.startRecording();

                /////Encoding:
                Encoder encoder = new G711UCodec();
                byte[] outBuffer = new byte[minBufSize];

                while(status == true) {

                    //reading data from MIC into buffer
                    minBufSize = recorder.read(buffer, 0, buffer.length);
                    //Encoding:
                    encoder.encode(buffer, minBufSize, outBuffer, 0);

                    //putting buffer in the packet
                    packet = new DatagramPacket (outBuffer, outBuffer.length, destination,port);

                    socket.send(packet);
                }

            } catch(UnknownHostException e) {
                Log.e("VS", "UnknownHostException");
            } catch (IOException e) {
                e.printStackTrace();
                Log.e("VS", "IOException");
            } 
        }

    });
    streamThread.start();
 }

以及播放和解码流的方法:

    public void playerAudioDecoding()
{
    Thread thrd = new Thread(new Runnable() {
        @Override
        public void run() 
        {
            android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

            AudioTrack track = new AudioTrack(AudioManager.STREAM_MUSIC, 
                    sampleRate, AudioFormat.CHANNEL_CONFIGURATION_MONO, 
                    AudioFormat.ENCODING_PCM_16BIT, minBufSize, 
                    AudioTrack.MODE_STREAM);
            track.play();

            Decoder decoder = new G711UCodec();

            try
            {
                DatagramSocket sock = new DatagramSocket(port);
                byte[] buf = new byte[minBufSize];

                while(true)
                {
                    DatagramPacket pack = new DatagramPacket(buf, minBufSize);
                    sock.receive(pack);

                    //Decoding:
                    int size = pack.getData().length;
                    short[] shortArray = new short[size];

                    decoder.decode(shortArray, pack.getData(), minBufSize, 0);
                    byte[] array = MyShortToByte(shortArray);
                    track.write(array, 0, array.length);
                }
            }
            catch (SocketException se)
            {
                Log.e("Error", "SocketException: " + se.toString());
            }
            catch (IOException ie)
            {
                Log.e("Error", "IOException" + ie.toString());
            }
        } // end run
    });
    thrd.start();
}

这是我使用 Apache 许可证的编解码器类:

public class G711UCodec implements Encoder, Decoder {
// s00000001wxyz...s000wxyz
// s0000001wxyza...s001wxyz
// s000001wxyzab...s010wxyz
// s00001wxyzabc...s011wxyz
// s0001wxyzabcd...s100wxyz
// s001wxyzabcde...s101wxyz
// s01wxyzabcdef...s110wxyz
// s1wxyzabcdefg...s111wxyz

private static byte[] table13to8 = new byte[8192];
private static short[] table8to16 = new short[256];

static {
    // b13 --> b8
    for (int p = 1, q = 0; p <= 0x80; p <<= 1, q+=0x10) {
        for (int i = 0, j = (p << 4) - 0x10; i < 16; i++, j += p) {
            int v = (i + q) ^ 0x7F;
            byte value1 = (byte) v;
            byte value2 = (byte) (v + 128);
            for (int m = j, e = j + p; m < e; m++) {
                table13to8[m] = value1;
                table13to8[8191 - m] = value2;
            }
        }
    }

    // b8 --> b16
    for (int q = 0; q <= 7; q++) {
        for (int i = 0, m = (q << 4); i < 16; i++, m++) {
            int v = (((i + 0x10) << q) - 0x10) << 3;
            table8to16[m ^ 0x7F] = (short) v;
            table8to16[(m ^ 0x7F) + 128] = (short) (65536 - v);
        }
    }
}

public int decode(short[] b16, byte[] b8, int count, int offset) {
    for (int i = 0, j = offset; i < count; i++, j++) {
        b16[i] = table8to16[b8[j] & 0xFF];
    }
    return count;
}

public int encode(short[] b16, int count, byte[] b8, int offset) {

    for (int i = 0, j = offset; i < count; i++, j++) {
        b8[j] = table13to8[(b16[i] >> 4) & 0x1FFF];
    }
    return count;
}

public int getSampleCount(int frameSize) {
    return frameSize;
}

真的，我不知道发生了什么；如果我将 sampleRate 更改为 4000，我可以识别我的声音和一些单词，但有很多回声。我再说一遍，如果禁用编码/解码过程并在 PCM 中进行流式传输，质量会很棒。让我看看是否有人可以帮助我，在此先感谢您。

最佳答案

好吧，我终于自己解决了编码/解码音频的问题。上周这是一项烦人的任务。我的代码的主要问题是编码做得很好但解码不是所以我正在解决它并在其他资源的帮助下修改这些类并且我已经创建了我自己的编码/解码方法(并且这些正在工作就像一个魅力!!!)。

另一个重要的决定是改变编码格式。现在我使用的是 alaw，不再是 ulaw。我进行此更改的唯一原因是因为以编程方式实现 alaw 比 ulaw 更容易。

此外，我还必须经常使用缓冲区大小等参数。

我将提交我的代码，我希望你们中的某些人可以使用我的引用资料节省大量时间。

    private int port=50005;
private int sampleRate = 8000; //44100;
private int channelConfig = AudioFormat.CHANNEL_IN_MONO;    
private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;       
int minBufSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);

public void startStreamingEncoding() {

    Thread streamThread = new Thread(new Runnable() {

        @Override
        public void run() {
            try {

                android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

                DatagramSocket socket = new DatagramSocket();

                byte[] buffer = new byte[4096];

                DatagramPacket packet;

                final InetAddress destination = InetAddress.getByName(ip_receiver); 

                recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,sampleRate,channelConfig,audioFormat, minBufSize * 10);

                recorder.startRecording();

                /////Encoding:
                CMG711 encoder = new CMG711();
                byte[] outBuffer = new byte[4096];

                int read, encoded;
                File sdCard = Environment.getExternalStorageDirectory();
                FileOutputStream out = new FileOutputStream( new File( sdCard ,"audio-bernard.raw" ));

                while(status == true) {

                    //reading data from MIC into buffer
                    read = recorder.read(buffer, 0, buffer.length);
                    Log.d(getTag(), "read: "+read );

                    //Encoding:
                    encoded = encoder.encode(buffer,0, read, outBuffer);                      

                    //putting buffer in the packet
                    packet = new DatagramPacket (outBuffer, encoded, destination,port);
                    out.write( outBuffer, 0, encoded );

                    socket.send(packet);
                }

            } catch(UnknownHostException e) {
                Log.e("VS", "UnknownHostException");
            } catch (IOException e) {
                e.printStackTrace();
                Log.e("VS", "IOException");
            } 
        }

    });
    streamThread.start();
 }

对于接收器和播放器类或方法:

private int port=50005;
private int sampleRate = 8000 ;//44100;
private int channelConfig = AudioFormat.CHANNEL_OUT_MONO;    
private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;       
int minBufSize = AudioTrack.getMinBufferSize(sampleRate, channelConfig, audioFormat);


 public void playerAudioDecodingBernard()
    {
        Thread thrd = new Thread(new Runnable() {
            @Override
            public void run() 
            {
                android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);

                AudioTrack track = new AudioTrack(AudioManager.STREAM_MUSIC, 
                        sampleRate, AudioFormat.CHANNEL_OUT_MONO, 
                        AudioFormat.ENCODING_PCM_16BIT, minBufSize * 10, 
                        AudioTrack.MODE_STREAM);


                CMG711 decoder = new CMG711();

                try
                {
                    DatagramSocket sock = new DatagramSocket(port);
                    byte[] buf = new byte[4096];

                    int frame = 0;
                    while(true)
                    {
                        DatagramPacket pack = new DatagramPacket(buf, 4096);
                        sock.receive(pack);

                        //Decoding:                         
                        int size = pack.getLength();
                        //Log.d( "Player", "Player: "+ size +", "+pack.getLength() + ", "+pack.getOffset() );
                        byte[] byteArray = new byte[size*2];

                        decoder.decode(pack.getData(), 0, size, byteArray);
                        track.write(byteArray, 0, byteArray.length);

                        if( frame++ > 3 )
                            track.play();
                    }
                }
                catch (SocketException se)
                {
                    Log.e("Error", "SocketException: " + se.toString());
                }
                catch (IOException ie)
                {
                    Log.e("Error", "IOException" + ie.toString());
                }
            } // end run
        });
        thrd.start();
    }

这是 alaw 格式的编码/解码类:

public class CMG711
{
/** decompress table constants */
private static short aLawDecompressTable[] = new short[]
{ -5504, -5248, -6016, -5760, -4480, -4224, -4992, -4736, -7552, -7296, -8064, -7808, -6528, -6272, -7040, -6784, -2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368, -3776, -3648, -4032, -3904, -3264, -3136, -3520, -3392, -22016, -20992, -24064, -23040, -17920, -16896, -19968, -18944, -30208, -29184, -32256, -31232, -26112, -25088, -28160, -27136, -11008, -10496, -12032, -11520, -8960, -8448, -9984, -9472, -15104, -14592, -16128, -15616, -13056, -12544, -14080, -13568, -344, -328, -376,
        -360, -280, -264, -312, -296, -472, -456, -504, -488, -408, -392, -440, -424, -88, -72, -120, -104, -24, -8, -56, -40, -216, -200, -248, -232, -152, -136, -184, -168, -1376, -1312, -1504, -1440, -1120, -1056, -1248, -1184, -1888, -1824, -2016, -1952, -1632, -1568, -1760, -1696, -688, -656, -752, -720, -560, -528, -624, -592, -944, -912, -1008, -976, -816, -784, -880, -848, 5504, 5248, 6016, 5760, 4480, 4224, 4992, 4736, 7552, 7296, 8064, 7808, 6528, 6272, 7040, 6784, 2752, 2624,
        3008, 2880, 2240, 2112, 2496, 2368, 3776, 3648, 4032, 3904, 3264, 3136, 3520, 3392, 22016, 20992, 24064, 23040, 17920, 16896, 19968, 18944, 30208, 29184, 32256, 31232, 26112, 25088, 28160, 27136, 11008, 10496, 12032, 11520, 8960, 8448, 9984, 9472, 15104, 14592, 16128, 15616, 13056, 12544, 14080, 13568, 344, 328, 376, 360, 280, 264, 312, 296, 472, 456, 504, 488, 408, 392, 440, 424, 88, 72, 120, 104, 24, 8, 56, 40, 216, 200, 248, 232, 152, 136, 184, 168, 1376, 1312, 1504, 1440, 1120,
        1056, 1248, 1184, 1888, 1824, 2016, 1952, 1632, 1568, 1760, 1696, 688, 656, 752, 720, 560, 528, 624, 592, 944, 912, 1008, 976, 816, 784, 880, 848 };

private final static int cClip = 32635;
private static byte aLawCompressTable[] = new byte[]
{ 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 };

public int encode( byte[] src, int offset, int len, byte[] res )
{
    int j = offset;
    int count = len / 2;
    short sample = 0;

    for ( int i = 0; i < count; i++ )
    {
        sample = (short) ( ( ( src[j++] & 0xff ) | ( src[j++] ) << 8 ) );
        res[i] = linearToALawSample( sample );
    }
    return count;
}

private byte linearToALawSample( short sample )
{
    int sign;
    int exponent;
    int mantissa;
    int s;

    sign = ( ( ~sample ) >> 8 ) & 0x80;
    if ( !( sign == 0x80 ) )
    {
        sample = (short) -sample;
    }
    if ( sample > cClip )
    {
        sample = cClip;
    }
    if ( sample >= 256 )
    {
        exponent = (int) aLawCompressTable[( sample >> 8 ) & 0x7F];
        mantissa = ( sample >> ( exponent + 3 ) ) & 0x0F;
        s = ( exponent << 4 ) | mantissa;
    }
    else
    {
        s = sample >> 4;
    }
    s ^= ( sign ^ 0x55 );
    return (byte) s;
}

public void decode( byte[] src, int offset, int len, byte[] res )
{
    int j = 0;
    for ( int i = 0; i < len; i++ )
    {
        short s = aLawDecompressTable[src[i + offset] & 0xff];
        res[j++] = (byte) s;
        res[j++] = (byte) ( s >> 8 );
    }
}
}

希望对你们有用!无论如何，感谢您提供的帮助，特别感谢 bonnyz。

关于android - 将录音编码和解码为 G711 ( PCMU - uLaw) 格式，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23273866/

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