Optical flow using Hybrid -- Possible?

[Selur]

Apparently, no one uses the motion vectors stored in the source frames. Do you know why?

Oh there was an old discussion about that over at doom9s years ago as a side discussion whether they could be used using compression.
Is I recall correctly the main points were:
a. you need a specific source filter to extract them properly. (lot of work, but propably not too complicated)
b. motion vectors from the compressed formats are often not ideal and usually reusing them would give you only a roughly relyable compression. Through some tests it was determined that recalculating motion vectors produces waay better results.
c. also the motion vectors from the compressed formats might need different interpretation depending on the video format

Here's an example of the sort of stuff I've posted to Doom9, Vapoursynth: ...

I never really had time and motivation to really dive into the whole motion interpolation issue so much, but I'll probably keep an eye on the thread.

Cu Selur