注意：我的帖子中的所有信息仅适用于Samsung Galaxy S7设备.我不知道模拟器和其他设备的行为方式.

在onImageAvailable中,我将每个图像连续转换为NV21字节数组,并将其转发到期望原始NV21格式的API.

这是我初始化图像阅读器和接收图像的方法：

private void openCamera() {
    ...
    mImageReader = ImageReader.newInstance(WIDTH, HEIGHT,
            ImageFormat.YUV_420_888, 1); // only 1 for best performance
    mImageReader.setOnImageAvailableListener(
    mOnImageAvailableListener, mBackgroundHandler);
    ...
}

private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
        = new ImageReader.OnImageAvailableListener() {

    @Override
    public void onImageAvailable(ImageReader reader) {
        Image image = reader.acquireLatestImage();
        if (image != null) {
            byte[] data = convertYUV420ToNV21_ALL_PLANES(image); // this image is turned 90 deg using front cam in portrait mode
            byte[] data_rotated = rotateNV21_working(data, WIDTH, HEIGHT, 270);
            ForwardToAPI(data_rotated); // image data is being forwarded to api and received later on
            image.close();
        }
    }
};

将图像转换为原始NV21(from here)的功能,工作正常,在纵向模式下使用前凸轮时,图像(由于android？)转动90度：
(根据Alex Cohn的评论,我对其进行了修改)

private byte[] convertYUV420ToNV21_ALL_PLANES(Image imgYUV420) {

    byte[] rez;

    ByteBuffer buffer0 = imgYUV420.getPlanes()[0].getBuffer();
    ByteBuffer buffer1 = imgYUV420.getPlanes()[1].getBuffer();
    ByteBuffer buffer2 = imgYUV420.getPlanes()[2].getBuffer();

    // actually here should be something like each second byte
    // however I simply get the last byte of buffer 2 and the entire buffer 1
    int buffer0_size = buffer0.remaining();
    int buffer1_size = buffer1.remaining(); // / 2 + 1;
    int buffer2_size = 1;//buffer2.remaining(); // / 2 + 1;

    byte[] buffer0_byte = new byte[buffer0_size];
    byte[] buffer1_byte = new byte[buffer1_size];
    byte[] buffer2_byte = new byte[buffer2_size];

    buffer0.get(buffer0_byte, 0, buffer0_size);
    buffer1.get(buffer1_byte, 0, buffer1_size);
    buffer2.get(buffer2_byte, buffer2_size-1, buffer2_size);


    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
    try {
        // swap 1 and 2 as blue and red colors are swapped
        outputStream.write(buffer0_byte);
        outputStream.write(buffer2_byte);
        outputStream.write(buffer1_byte);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    rez = outputStream.toByteArray();

    return rez;
}

因此需要轮换“数据”.使用此功能(from here),我得到一个奇怪的3次隔行扫描图片错误：

public static byte[] rotateNV21(byte[] input, int width, int height, int rotation) {
    byte[] output = new byte[input.length];
    boolean swap = (rotation == 90 || rotation == 270);
    // **EDIT:** in portrait mode & front cam this needs to be set to true:
    boolean yflip = true;// (rotation == 90 || rotation == 180);
    boolean xflip = (rotation == 270 || rotation == 180);
    for (int x = 0; x < width; x++) {
        for (int y = 0; y < height; y++) {
            int xo = x, yo = y;
            int w = width, h = height;
            int xi = xo, yi = yo;
            if (swap) {
                xi = w * yo / h;
                yi = h * xo / w;
            }
            if (yflip) {
                yi = h - yi - 1;
            }
            if (xflip) {
                xi = w - xi - 1;
            }
            output[w * yo + xo] = input[w * yi + xi];
            int fs = w * h;
            int qs = (fs >> 2);
            xi = (xi >> 1);
            yi = (yi >> 1);
            xo = (xo >> 1);
            yo = (yo >> 1);
            w = (w >> 1);
            h = (h >> 1);
            // adjust for interleave here
            int ui = fs + (w * yi + xi) * 2;
            int uo = fs + (w * yo + xo) * 2;
            // and here
            int vi = ui + 1;
            int vo = uo + 1;
            output[uo] = input[ui];
            output[vo] = input[vi];
        }
    }
    return output;
}

导致这张图片：

注意：它仍然是相同的杯子,但你看到它3-4次.

使用另一个建议的旋转功能from here给出了正确的结果：

public static byte[] rotateNV21_working(final byte[] yuv,
                                final int width,
                                final int height,
                                final int rotation)
{
  if (rotation == 0) return yuv;
  if (rotation % 90 != 0 || rotation < 0 || rotation > 270) {
    throw new IllegalArgumentException("0 <= rotation < 360, rotation % 90 == 0");
  }

  final byte[]  output    = new byte[yuv.length];
  final int     frameSize = width * height;
  final boolean swap      = rotation % 180 != 0;
  final boolean xflip     = rotation % 270 != 0;
  final boolean yflip     = rotation >= 180;

  for (int j = 0; j < height; j++) {
    for (int i = 0; i < width; i++) {
      final int yIn = j * width + i;
      final int uIn = frameSize + (j >> 1) * width + (i & ~1);
      final int vIn = uIn       + 1;

      final int wOut     = swap  ? height              : width;
      final int hOut     = swap  ? width               : height;
      final int iSwapped = swap  ? j                   : i;
      final int jSwapped = swap  ? i                   : j;
      final int iOut     = xflip ? wOut - iSwapped - 1 : iSwapped;
      final int jOut     = yflip ? hOut - jSwapped - 1 : jSwapped;

      final int yOut = jOut * wOut + iOut;
      final int uOut = frameSize + (jOut >> 1) * wOut + (iOut & ~1);
      final int vOut = uOut + 1;

      output[yOut] = (byte)(0xff & yuv[yIn]);
      output[uOut] = (byte)(0xff & yuv[uIn]);
      output[vOut] = (byte)(0xff & yuv[vIn]);
    }
  }
  return output;
}

现在结果很好：

顶部图像使用纹理视图的表面显示直接流并将其添加到captureRequestBuilder.底部图像显示旋转后的原始图像数据.

问题是：

>这对“convertYUV420ToNV21_ALL_PLANES”的攻击是否有效
设备/模拟器？
>为什么rotateNV21不起作用,而rotateNV21_working工作正常.

编辑：镜像问题已修复,请参阅代码注释.挤压问题是固定的,它是由它转发的API引起的.
实际的开放问题是一个适当的不太昂贵的功能,将图像转换并旋转到在任何设备上工作的原始NV21.

解决方法:

所以,这是将Image转换为NV21 byte []的正确代码.这将工作我们imgYUV420 U和V平面有pixelStride = 1(如在模拟器上)或pixelStride = 1(如在Nexus上)：

private byte[] convertYUV420ToNV21_ALL_PLANES(Image imgYUV420) {

    assert(imgYUV420.getFormat() == ImageFormat.YUV_420_888);
    Log.d(TAG, "image: " + imgYUV420.getWidth() + "x" + imgYUV420.getHeight() + " " + imgYUV420.getFormat());
    Log.d(TAG, "planes: " + imgYUV420.getPlanes().length);
    for (int nplane = 0; nplane < imgYUV420.getPlanes().length; nplane++) {
        Log.d(TAG, "plane[" + nplane + "]: length " + imgYUV420.getPlanes()[nplane].getBuffer().remaining() + ", strides: " + imgYUV420.getPlanes()[nplane].getPixelStride() + " " + imgYUV420.getPlanes()[nplane].getRowStride());
    }

    byte[] rez = new byte[imgYUV420.getWidth() * imgYUV420.getHeight() * 3 / 2];
    ByteBuffer buffer0 = imgYUV420.getPlanes()[0].getBuffer();
    ByteBuffer buffer1 = imgYUV420.getPlanes()[1].getBuffer();
    ByteBuffer buffer2 = imgYUV420.getPlanes()[2].getBuffer();

    int n = 0;
    assert(imgYUV420.getPlanes()[0].getPixelStride() == 1);
    for (int row = 0; row < imgYUV420.getHeight(); row++) {
        for (int col = 0; col < imgYUV420.getWidth(); col++) {
            rez[n++] = buffer0.get();
        }
    }
    assert(imgYUV420.getPlanes()[2].getPixelStride() == imgYUV420.getPlanes()[1].getPixelStride());
    int stride = imgYUV420.getPlanes()[1].getPixelStride();
    for (int row = 0; row < imgYUV420.getHeight(); row += 2) {
        for (int col = 0; col < imgYUV420.getWidth(); col += 2) {
            rez[n++] = buffer1.get();
            rez[n++] = buffer2.get();
            for (int skip = 1; skip < stride; skip++) {
                if (buffer1.remaining() > 0) {
                    buffer1.get();
                }
                if (buffer2.remaining() > 0) {
                    buffer2.get();
                }
            }
        }
    }

    Log.w(TAG, "total: " + rez.length);
    return rez;
}

如您所见,可以非常轻松地更改此代码,从而在一个步骤中生成旋转图像：

private byte[] rotateYUV420ToNV21(Image imgYUV420) {

    Log.d(TAG, "image: " + imgYUV420.getWidth() + "x" + imgYUV420.getHeight() + " " + imgYUV420.getFormat());
    Log.d(TAG, "planes: " + imgYUV420.getPlanes().length);
    for (int nplane = 0; nplane < imgYUV420.getPlanes().length; nplane++) {
        Log.d(TAG, "plane[" + nplane + "]: length " + imgYUV420.getPlanes()[nplane].getBuffer().remaining() + ", strides: " + imgYUV420.getPlanes()[nplane].getPixelStride() + " " + imgYUV420.getPlanes()[nplane].getRowStride());
    }

    byte[] rez = new byte[imgYUV420.getWidth() * imgYUV420.getHeight() * 3 / 2];
    ByteBuffer buffer0 = imgYUV420.getPlanes()[0].getBuffer();
    ByteBuffer buffer1 = imgYUV420.getPlanes()[1].getBuffer();
    ByteBuffer buffer2 = imgYUV420.getPlanes()[2].getBuffer();

    int width = imgYUV420.getHeight();
    assert(imgYUV420.getPlanes()[0].getPixelStride() == 1);
    for (int row = imgYUV420.getHeight()-1; row >=0; row--) {
        for (int col = 0; col < imgYUV420.getWidth(); col++) {
            rez[col*width+row] = buffer0.get();
        }
    }
    int uv_offset = imgYUV420.getWidth()*imgYUV420.getHeight();
    assert(imgYUV420.getPlanes()[2].getPixelStride() == imgYUV420.getPlanes()[1].getPixelStride());
    int stride = imgYUV420.getPlanes()[1].getPixelStride();
    for (int row = imgYUV420.getHeight() - 2; row >= 0; row -= 2) {
        for (int col = 0; col < imgYUV420.getWidth(); col += 2) {
            rez[uv_offset+col/2*width+row] = buffer1.get();
            rez[uv_offset+col/2*width+row+1] = buffer2.get();
            for (int skip = 1; skip < stride; skip++) {
                if (buffer1.remaining() > 0) {
                    buffer1.get();
                }
                if (buffer2.remaining() > 0) {
                    buffer2.get();
                }
            }
        }
    }

    Log.w(TAG, "total rotated: " + rez.length);
    return rez;
}

我真诚地推荐网站http://rawpixels.net/来查看原始图像的实际结构.