in sense my mod apparently  just leaks (swsContext?) so it can't play even 20 sec of 1440*1080 video to completion in termux, running on tablet with 3Gb ram.

There seems to be difference if I set thread count manually (on file reading only for now) but it looks negative, in other words higher thread count -> slower total playback .. tried 8, 4,1,16 on 8 cpu tablet. Speed was going down from 18 fps for unaltered cingg to 13 with 8 threads and crash/oom with 16 ;)

And if I try to use sws_scale_frame I just got all blank/black frames  on timeline ....

I think switching to sws_scale_frame is important if we want to try new colormanagement support in ffmpeg.git ...

Resources used, apart from that Blender diff: