混合兩個文件在Android上的音頻WAV使用短數組

Question

編寫我的程序，但是效果不是很好，我不知道自己哪里寫錯了。 在此之前，我使用byte []來存儲來自wav的數據（它工作得很好，但是很吵），所以我切換到short []，但是結果非常糟糕。

這是我的代碼：

public class Mix extends Activity {


@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 {

    in1 = getResources().openRawResource(R.raw.media_b); //16-bit little-endian, 1411kbps, 44100Hz, 2 channels 
    in2 = getResources().openRawResource(R.raw.media_c); //16-bit little-endian, 1411kbps, 44100Hz, 2 channels 

    List<Short> music1  =  createMusicArray(in1);
    List<Short> music2  =  createMusicArray(in2);

    completeStreams(music1, music2);

    short[] arrayMusic1 = buildShortArray(music1);;
    short[] arrayMusic2 = buildShortArray(music2);

    output = new short[arrayMusic1.length];

    for (int i = 0; i < output.length; i++) {


    }

    saveToFile();
}




/**
 * createMusicArray reads the stream and returns a list of short objects (the samples)
 */
public List<Short> createMusicArray (InputStream ins) throws IOException {
    List<Short> musicList = new ArrayList<Short>();

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] byteArray           = new byte[50*1024];
    int i = Integer.MAX_VALUE;
    while ((i = ins.read(byteArray, 0, byteArray.length)) > 0) {
        baos.write(byteArray, 0, i);
    }

    for (int j = 0; j < byteArray.length; j++) {
        short objShort = (short)(byteArray[j]); 
        musicList.add(objShort);
    }

    return musicList;

}

/**
 * completeStreams normalizes the streams by adding  a series of '0' shorts at the end of smaller files. At the end the 2 files have all the same length.
 */
public void completeStreams(List<Short> mListShort_1, List<Short> mListShort_2) {
    //TODO: check length
    int size_a = mListShort_1.size();
    int size_b = mListShort_2.size();

    if (size_a > size_b){
        // adding series of '0'
        for (int i = size_b+1; i <= size_a; i++) {
            mListShort_2.set(i, (short) 0);
        }
    } else if (size_a < size_b) {
        for (int i = size_a+1; i <= size_b; i++) {
            mListShort_1.set(i, (short) 0);
        }
    } else {
        //do nothing
    }
}




private byte[] shortArrayToByteArray(short[] shortArr) {
    /**
    int index;
    int iterations = shortArr.length;
    ByteBuffer byteBuffer = ByteBuffer.allocate(shortArr.length * 2);

    for(index = 0; index != iterations; ++index){
      byteBuffer.putShort(shortArr[index]);    
    }

    return byteBuffer.array();
    */

    int short_index, byte_index;
    int iterations = shortArr.length;

    byte [] buffer = new byte[shortArr.length * 2];

    short_index = byte_index = 0;

    for(/*NOP*/; short_index != iterations; /*NOP*/) {
        buffer[byte_index]      =   (byte) (shortArr[short_index] & 0x00FF); 
        buffer[byte_index + 1]  =   (byte) ((shortArr[short_index] & 0xFF00) >> 8);

        ++short_index; byte_index += 2;
    }

    return buffer;
}

private 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;
}

private byte[] shortToByteArray(short data) {
    byte[] b = new byte[2];
    b[0] = (byte) (data & 0xff);
    b[1] = (byte) ((data >> 8) & 0xff);
    return b;
}

public static long byteArrayToLong(byte[] b) {
    int  start = 0;
    int      i = 0;
    int    len = 4;
    int    cnt = 0;
    byte[] tmp = new byte[len];
    for (i = start; i < (start + len); i++) {
        tmp[cnt] = b[i];
        cnt++;
    }
    long accum = 0;
    i = 0;
    for (int shiftBy = 0; shiftBy < 32; shiftBy += 8) {
        accum |= ((long) (tmp[i] & 0xff)) << shiftBy;
        i++;
    }
    return accum;
}

}

你能幫助我嗎。 非常感謝你！

Answer 1

您的主要問題在於此功能：

/**
 * createMusicArray reads the stream and returns a list of short objects (the samples)
 */
public List<Short> createMusicArray (InputStream ins) throws IOException {
    List<Short> musicList = new ArrayList<Short>();

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] byteArray           = new byte[50*1024];
    int i = Integer.MAX_VALUE;
    while ((i = ins.read(byteArray, 0, byteArray.length)) > 0) {
        baos.write(byteArray, 0, i);
    }

    for (int j = 0; j < byteArray.length; j++) {
        short objShort = (short)(byteArray[j]); 
        musicList.add(objShort);
    }

    return musicList;
}

看來您正在獲取原始字節並將其簡單地轉換為短褲，但是每個短褲都需要從文件中的兩個字節讀取數據。 （請參閱如何在shortArrayToByteArray函數中正確處理此問題）。 讀取文件的原始短褲的最簡單方法是使用DataInputStream。 不幸的是，您還需要擔心字節順序，因此您需要從guava獲取LittleEndianDataInputStream，或者如果您不想導入整個guava庫，則可以編寫自己的類來執行相同的操作，例如this 。 嘗試以下操作（未經測試，因此您可能需要對其進行調整）：

/**
 * createMusicArray reads the stream and returns a list of short objects (the samples)
 */
public List<Short> createMusicArray (InputStream ins) throws IOException {
    LittleEndianDataInputStream dis = new LittleEndianDataInputStream(ins);

    while (true) {
        try {
            short d = dis.readShort();
            musicList.add(d);
        } catch( EOFException e ) {
            break;
        }
    }

    return musicList;
}

附帶說明一下，將所有數據存儲在列表中然后將其傳輸到數組中是非常低效的（而且令人困惑）。 您應該考慮只使用ArrayList，或者更好地獲取媒體數據的大小，並首先使用它來構建正確大小的數組。 但是，所有這些都不能確保您仍可以執行該操作，因為您正在嘗試將整個文件放入內存中。 取而代之的是，嘗試讀取每個文件的較小塊，並將其混合，然后讀取下一個塊。

但是在您開始工作之前，我不會擔心所有這些。