int w = width, h = height;
int wo = height, h0 = width; // add this

Then, for every transformation to output, use the (wo, ho) in place of (w, h). Example:

output[wo * yo + xo] = input[wo * yi + xi];

Sorry, I know it’s a little vague. Play around and see what you get. Good luck!

Thanks for the wonderful blog, very informative and helpful.
The rotateNV21toYUV420 you provided works great but the dimensions of the byte[] are kept intact, I mean byte[] obtained from onPreviewFrame() in portrait mode is 176*144 and after applying the method you provided the dimensions are still 176*144, could you please point to me what changes would be needed to make it 144*176 dimensions.

The output format is IYUV, which is supposed to be compatible with I420. However, see http://www.fourcc.org/yuv.php#IYUV for a discussion of this topic…it isn’t clear if they really are the same. Wish I could tell you more.

Chris

You could try playing with the swap/flip flags. Invert one (flip = !flip) then the other (swap = !swap) and see what you get.

Chris

I used Your function to rotate bytes in ‘onPreviewFrame’. And the thing is that the image gets rotated for 90 degrees but is also mirrored and flipped. Do You have any suggestions on how to just get image rotated.

Regards,
Domagoj

Sorry, my mistake! The NV21 format has the UV planes interleaved, so my original statement was wrong. I’ve just written and tested the following code on an NV21 stream, and it worked fine.

public static void rotateNV21toYUV420(byte[] input, byte[] output, int width, int height, int rotation) {
	boolean swap = (rotation == 90 || rotation == 270);
	boolean flip = (rotation == 90 || 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 (flip) {
				xi = w - xi - 1;
				yi = h - yi - 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;
			// and here
			int vi = ui + 1;
			int vo = qs + uo;
			output[uo] = input[vi]; 
			output[vo] = input[ui]; 
		}
	}
}	

Hope that works for you!

Regards,
Chris

In the NV21,

output[uo] = input[vi];
output[vo] = input[ui];

to read:

output[uo] = input[ui];
output[vo] = input[vi]

not work well.How can I do?

NV21 should be very close to YV12, except the U and V color planes are swapped. You should be able to get it working just by changing these lines:

output[uo] = input[vi];
output[vo] = input[ui];

to read:

output[uo] = input[ui];
output[vo] = input[vi];

Give that a try.

Regards,
Chris

where you rotate NV12 image I want to rotate NV21 image comes from android camera I checked your function but I loose color information of image using that.May be due to NV12 and I pass NV21 to function as input. can you help lil bit in this please ? its very useful function for me.