Implement a safe get_write_ptr() that respects COW and allow get_read_ptr() to safely work on all frames as well
Implement a safe get_write_ptr() that respects COW and allow get_read_ptr() to safely work on all frames as well

vapoursynth/vapoursynth,vapoursynth/vapoursynth,vapoursynth/vapoursynth,vapoursynth/vapoursynth