Separate Y and UV of a video frame C++

Question

I am receiving a video frame in a GstVideoFrame structure of a gstreamer element which is written in C++.

The frame is in YUV420 NV12 format

In this gstreamer element, I am trying to copy y-frame and uv-frame in separate buffers.

According to videolan.org, the YUV420 NV12 data is stored as following in the incoming frame buffer : (info copied from website)

NV12:

Related to I420, NV12 has one luma "luminance" plane Y and one plane with U and V values interleaved.

In NV12, chroma planes (blue and red) are subsampled in both the horizontal and vertical dimensions by a factor of 2.

For a 2×2 group of pixels, you have 4 Y samples and 1 U and 1 V sample.

It can be helpful to think of NV12 as I420 with the U and V planes interleaved.

Here is a graphical representation of NV12. Each letter represents one bit:

    For 1 NV12 pixel: YYYYYYYY UVUV
    For a 2-pixel NV12 frame: YYYYYYYYYYYYYYYY UVUVUVUV
    For a 50-pixel NV12 frame: Y×8×50 (UV)×2×50
    For a n-pixel NV12 frame: Y×8×n (UV)×2×n

but I cant seem to calculate the offset of y-data and uv-data in the buffer.

Update_1 : I have height and width of the frame to calculate the size of y-data and uv-data as:

y_size = width * height;
uv_size = y_size / 2;

any help or comments regarding this will be appreciated.

thanks

Answer 1

Thanks to @Ext3h, this is how I was able to separate y-data and uv-data from incoming YUV frame.

y_data = (u8 *)GST_VIDEO_FRAME_PLANE_DATA (in_frame, 0);
uv_data =(u8 *)GST_VIDEO_FRAME_PLANE_DATA (in_frame, 1);