audio - WAVE文件格式

Question

我正在制作一个可生成信号并将其另存为wave文件的android应用程序。我到处看，发现我应该像here一样“手动”“编写”文件的结构，因为Android不支持wave格式。

该文件已生成，但不是“可播放的”，即使在Matlab上我也收到此消息:Incorrect chunk size information in WAV file. 这是代码，如果结构有问题，请告诉我。

public class MainActivity extends Activity {  

int duration=1;
int sampleRate=48000;
int numSample=duration*sampleRate;
double sample[]=new double[numSample];
double freq1=23000;
double freq2=24000;
byte[] generatedSnd= new byte[2*numSample];
Handler handler=new Handler();
long mySubChunk1Size = 16;
short myBitsPerSample= 16;
int myFormat = 1;
int myChannels = 1;
long myByteRate = sampleRate * myChannels * myBitsPerSample/8;
int myBlockAlign = (int) (myChannels * myBitsPerSample/8);
long myChunk2Size = generatedSnd.length* myChannels * myBitsPerSample/8;
long myChunkSize = 36 + myChunk2Size;


@Override 
protected void onCreate(Bundle savedInstanceState) {  

    super.onCreate(savedInstanceState);  
    setContentView(R.layout.activity_main);
    Thread thread=new Thread(new Runnable(){
        public void run(){
            try {
                genTone();
            } catch (IOException e) {
                // TODO Auto-generated catch block                                                                                                                                                                                          

        e.printStackTrace();
    }
    handler.post(new Runnable(){
        public void run(){
            playSound();
        }
    });
}
    });
    thread.start();

}    

protected void onResume()
{
    super.onResume();

}
void genTone() throws IOException{


    double instfreq=0, numerator;

    for (int i=0;i<numSample; i++ )
    {
        numerator=(double)(i)/(double)numSample;
         instfreq   =freq1+(numerator*(freq2-freq1));
         if ((i % 1000) == 0) {
                Log.e("Current Freq:", String.format("Freq is:  %f at loop %d of %d", instfreq, i, numSample));
            }
        sample[i]=Math.sin(2*Math.PI*i/(sampleRate/instfreq));

    }
     int idx = 0;
        for (final double dVal : sample) {
            // scale to maximum amplitude
            final short val = (short) ((dVal * 32767)); // max positive sample for signed 16 bit integers is 32767
            // in 16 bit wave PCM, first byte is the low order byte (pcm: pulse control modulation)
            generatedSnd[idx++] = (byte) (val & 0x00ff);
            generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);


        }
       DataOutputStream dd=new DataOutputStream( new FileOutputStream(Environment.getExternalStorageDirectory().getAbsolutePath()+"/tessst.wav" ));    
      dd.writeBytes("RIFF");
      dd.writeInt(0); // Final file size not known yet, write 0 
      dd.writeBytes("WAVE");
      dd.writeBytes("fmt ");
      dd.writeInt(Integer.reverseBytes(16)); // Sub-chunk size, 16 for PCM
      dd.writeShort(Short.reverseBytes((short) 1)); // AudioFormat, 1 for PCM
      dd.writeShort(Short.reverseBytes( (short) myChannels));// Number of channels, 1 for mono, 2 for stereo
      dd.writeInt(Integer.reverseBytes(sampleRate)); // Sample rate
      dd.writeInt(Integer.reverseBytes( (sampleRate*myBitsPerSample*myChannels/8))); // Byte rate, SampleRate*NumberOfChannels*BitsPerSample/8
      dd.writeShort(Short.reverseBytes((short) (myChannels*myBitsPerSample/8))); // Block align, NumberOfChannels*BitsPerSample/8
      dd.writeShort(Short.reverseBytes( myBitsPerSample)); // Bits per sample
      dd.writeBytes("data");
      dd.write(generatedSnd,0,numSample);
      dd.close();


    }

Answer 1

看起来您还没有在音频数据(generatedSnd)之前写入“数据”块的大小。您还需要返回并在关闭流之前写入“RIFF”块的大小。在此示例代码中，您可以预先计算出该数值，而不必首先写入零。