根据YUV420P格式格式化缓冲区

Question

我有一个图像大小,640 x480我想使用yv12作为输出格式.一些API正在处理图像,我希望得到YV12格式的输出.

我现在正在尝试的是那个

int width = 640;
int height = 480;

byte [] byteArray = new byte [Convert.ToInt32((width*height +(2*((width*height)/ 4)))*1.5)];

captureDevice.GetPreviewBufferYCbCr(字节阵列)");

            int YLength = Convert.ToInt32(width * height * 1.5);

            // UVlength multipled by 2 because it is for both u and v
            int UVLength = Convert.ToInt32(2 * (width / 2) * (weight / 2)) * 1.5);

            var inputYBuffer = byteArray.AsBuffer(0, YLength);
            var inputUVBuffer = byteArray.AsBuffer(YLength, UVLength);


            var inputBuffers = new IBuffer[] { inputYBuffer, inputUVBuffer };
            var inputScanlines = new uint[] { (uint)YLength, (uint)UVLength  };
            /////Creating input buffer that supports Nv12 format

                Bitmap inputBtm = new Bitmap(
                outputBufferSize,
                ColorMode.Yvu420Sp,
                inputScanlines, // 1.5 bytes per pixel in  Yuv420Sp mode
                inputBuffers);



            //As v length is same as u length in output buffer so v length can be used in both place.
            int vLength = UVLength / 2;
            var outputYBuffer = byteArray.AsBuffer(0, YLength);
            var outputVBuffer = byteArray.AsBuffer(YLength, vLength);
            var outputUBuffer = byteArray.AsBuffer(YLength + vLength, vLength);

            var outputBuffers = new IBuffer[] { outputYBuffer, outputVBuffer, outputUBuffer };
            //
            var outputScanlines = new uint[] { (uint)YLength, (uint)vLength, (uint)vLength };


            Bitmap outputBtm = new Bitmap(
                outputBufferSize,
                ColorMode.Yuv420P,
                outputScanlines, 
                outputBuffers);**strong text**

所以我想问的是,我是否正在根据YUV420P格式正确创建outputbuffer.有一个API,我在其中传递NV12的输入缓冲区,我假设它将给我YV12(YUV420P)格式的输出缓冲区.所以我创建了Y平面,它有width x height x 1.5字节.1.5因为YV12是垫子的12比特,类似地U盘子具有width/2 x height/2 x 1.5字节并且类似地是V平面.我不关心YUV420P和YVU420P,只要我的格式正确,我只需要交换U和V平面.

Answer 1

YUV 4:2:0平面看起来像这样:

----------------------
|     Y      | Cb|Cr |
----------------------

哪里:

Y = width x height pixels (bytes)
Cb = Y / 4 pixels (bytes)
Cr = Y / 4 pixels (bytes)

Total num pixels (bytes) = width * height * 3 / 2

这是像素放置在4:2:0子采样中的方式:

如您所见,每个色度值在4个亮度像素之间共享.