Issue with writing YUV image frame in C/C++

Question

I am trying to convert an RGB frame, which is taken from OpenGL glReadPixels(), to a YUV frame, and write the YUV frame to a file (.yuv). Later on I would like to write it to a

Answer 1

I compiled your code and surely there is a problem when computing upos and vpos values. For me this worked (RGB to YUV NV12):

vpos = length + (windowWidth * (j/2)) + (i/2)*2;
upos = vpos + 1;