Red and Green color channels are swapped in ffmpeg rendered video

Question

I'm using code similiar to this to pipe OpenGL image data directly to ffmpeg. I'm using this readpixels call:

qglReadPixels( 0, 0, glConfig.vidWidth, glConfig.vidHeight, GL_RGB, GL_UNSIGNED_BYTE, 0 );

however I have to use GL_RGB instead of GL_RGBA. In the ffmpeg command line I change RGBA to RGB24 accordingly. However, the output videos color channels are messed up (red is swapped with green). I can't seem to find any color formats that are GRB, so is there some way to swap red and green channels in ffmpeg using colorchannelmixer ?

edit: this would involve setting RR to 0, RG to 1, GG to 0, GR to 1? What would the syntax for that be?

Thanks.

Answer 1

Assuming that only the red and green channels have to be swapped, use

colorchannelmixer=rr=0:rg=1:gr=1:gg=0