Mix âm thanh trong android

Question

Tôi cố gắng để theo liên kết này:

http://mobilengineering.blogspot.com/2012/06/audio-mix-and-record-in-android.html?showComment=1369622288028#c2333829870074273419

Nhưng sau khi trộn các file âm thanh, tập tin (mixed.wav) trên sdcard không thể được chơi, tôi làm không biết tại sao. Bạn có thể giúp tôi không ?. Thank you very much ..

mã của tôi này:

public class MainActivity mở rộng Hoạt động {

public static final int FREQUENCY = 44100; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    try { 
     mixSound(); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
} 

private void mixSound() throws IOException { 
    AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT, 44100, AudioTrack.MODE_STREAM); 

    InputStream in1 = getResources().openRawResource(R.raw.media_b); 
    InputStream in2 = getResources().openRawResource(R.raw.media_c); 

    byte[] arrayMusic1 = null; 
    arrayMusic1 = new byte[in1.available()]; 
    arrayMusic1 = createMusicArray(in1); 
    in1.close(); 

    byte[] arrayMusic2 = null; 
    arrayMusic2 = new byte[in2.available()]; 
    arrayMusic2 = createMusicArray(in2); 
    in2.close(); 


    byte[] output = new byte[arrayMusic1.length]; 

    audioTrack.play(); 

    for (int i = 0; i < output.length; i++) { 
     float samplef1 = arrayMusic1[i]/128.0f; 
     float samplef2 = arrayMusic2[i]/128.0f; 
     float mixed = samplef1 + samplef2; 

     // reduce the volume a bit: 
     mixed *= 0.8; 
     // hard clipping 
     if (mixed > 1.0f) mixed = 1.0f; 
     if (mixed < -1.0f) mixed = -1.0f; 

     byte outputSample = (byte) (mixed * 128.0f); 
     output[i]   = outputSample; 
    } 

    audioTrack.write(output, 0, output.length); 
    convertByteToFile(output); 
} 

public static byte[] createMusicArray(InputStream is) throws IOException { 

    ByteArrayOutputStream baos = new ByteArrayOutputStream(); 
    byte[] buff = new byte[10240]; 
    int i = Integer.MAX_VALUE; 
    while ((i = is.read(buff, 0, buff.length)) > 0) { 
     baos.write(buff, 0, i); 
    } 

    return baos.toByteArray(); // be sure to close InputStream in calling function 

} 

public static void convertByteToFile(byte[] fileBytes) throws FileNotFoundException { 

    BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(Environment.getExternalStorageDirectory().getPath()+"/mixed.wav")); 
    try { 
     bos.write(fileBytes); 
     bos.flush(); 
     bos.close();  
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
} 

}

Answer 1

Những gì bạn đang xuất ra chỉ là dữ liệu PCM. Tệp WAV hợp lệ cũng cần tiêu đề:

Offset Size Name   Description 
------------------------------------------------------------------------ 
0   4  ChunkID  Contains the letters "RIFF" in ASCII form 
           (0x52494646 big-endian form). 
4   4  ChunkSize  36 + SubChunk2Size, or more precisely: 
           4 + (8 + SubChunk1Size) + (8 + SubChunk2Size) 
           This is the size of the rest of the chunk 
           following this number. This is the size of the 
           entire file in bytes minus 8 bytes for the 
           two fields not included in this count: 
           ChunkID and ChunkSize. 
8   4  Format   Contains the letters "WAVE" 
           (0x57415645 big-endian form). 

12  4  Subchunk1ID Contains the letters "fmt " 
           (0x666d7420 big-endian form). 
16  4  Subchunk1Size 16 for PCM. This is the size of the 
           rest of the Subchunk which follows this number. 
20  2  AudioFormat PCM = 1 (i.e. Linear quantization) 
           Values other than 1 indicate some 
           form of compression. 
22  2  NumChannels Mono = 1, Stereo = 2, etc. 
24  4  SampleRate  8000, 44100, etc. 
28  4  ByteRate  == SampleRate * NumChannels * BitsPerSample/8 
32  2  BlockAlign  == NumChannels * BitsPerSample/8 
           The number of bytes for one sample including 
           all channels. I wonder what happens when 
           this number isn't an integer? 
34  2  BitsPerSample 8 bits = 8, 16 bits = 16, etc. 
      2  ExtraParamSize if PCM, then doesn't exist 
      X  ExtraParams space for extra parameters 

36  4  Subchunk2ID Contains the letters "data" 
           (0x64617461 big-endian form). 
40  4  Subchunk2Size == NumSamples * NumChannels * BitsPerSample/8 
           This is the number of bytes in the data. 
           You can also think of this as the size 
           of the read of the subchunk following this 
           number. 

Sau khi bạn ghi dữ liệu PCM.

(Reference).