[Libav-user] motion vectors extraction

[Carl Eugen Hoyos]

2016-12-05 22:07 GMT+01:00 Štěpán Šigut <sigut.stepan at gmail.com>:

> I am trying to efficiently extract motion vectors from h264 live
> stream for analysis and motion detection. Is there any way to parse
> motion vectors without actually decoding the whole frame? I am aware
> of 'extract_mvs.c' code, but when I was experimenting with it, the
> performance was pretty much the same as decoding h264 to rawvideo (I
> think it completely decodes every frame) so right now I see no benefit
> in performing analysis in compressed domain vs. pixel domain.

> In theory it should be possible and performance gain could be impressive.

Patch probably welcome, I suspect you need to add a new decoding
flag "only provide motion vectors".

Carl Eugen