How to swap bit U with bit V in YUV format - image-processing

Question

I want to swap the U and V bit in YUV format, from NV12
YYYYYYYY UVUV // each letter presents a bit
to NV21
YYYYYYYY VUVU
I leave the Y planar alone, and handle the U and V planar by the function below
uchar swap(uchar in) {
uchar out = ((in >> 1) & 0x55) | ((in << 1) & 0xaa);
return out;
}
But I cannot get the desired result, the colour of the output image still not correct.
How can I swap U and V planar correctly?

Answer 1

Found the problem. UV should be manipulated in byte format, not bit.
byte[] yuv = // ...
final int length = yuv.length;
for (int i1 = 0; i1 < length; i1 += 2) {
if (i1 >= width * height) {
byte tmp = yuv[i1];
yuv[i1] = yuv[i1+1];
yuv[i1+1] = tmp;
}
}

Answer 2

try this method (-_-)
IFrameCallback iFrameCallback = new IFrameCallback() {
#Override
public void onFrame(ByteBuffer frame) {
//get nv12 data
byte[] b = new byte[frame.remaining()];
frame.get(b);
//nv12 data to nv21
NV12ToNV21(b, 1280, 720);
//send NV21 data
BVPU.InputVideoData(nv21, nv21.length,
System.currentTimeMillis() * 1000, 1280, 720);
}
};
byte[] nv21;
private void NV12ToNV21(byte[] data, int width, int height) {
nv21 = new byte[data.length];
int framesize = width * height;
int i = 0, j = 0;
System.arraycopy(data, 0, nv21, 0, framesize);
for (i = 0; i < framesize; i++) {
nv21[i] = data[i];
}
for (j = 0; j < framesize / 2; j += 2) {
nv21[framesize + j - 1] = data[j + framesize];
}
for (j = 0; j < framesize / 2; j += 2) {
nv21[framesize + j] = data[j + framesize - 1];
}
}