av_image_fill_max_pixsteps(max_step, max_step_comp, desc);
s = (max_step_comp[plane] == 1 || max_step_comp[plane] == 2) ? desc->log2_chroma_w : 0;
av_image_fill_max_pixsteps(max_step, max_step_comp, desc);
s = (max_step_comp[plane] == 1 || max_step_comp[plane] == 2) ? desc->log2_chroma_w : 0;