[Libav-user] Motion estimation : replacement for deprecated AVFrame::motion_val ?

cyril poulet xenosender at gmail.com
Sat Mar 29 14:46:33 CET 2014

Thanks for the advice.
On my particular case, I'm interested in detecting overlays, so it's not
really about estimating the motion but more estimating what's not moving.
Recent papers have obtained good results by estimating a first approximate
overlay position directly on these MVs, though after that you effectively
have to work on parts of the decoded frames.
Anyway, thanks for the explanation !

2014-03-28 23:38 GMT+01:00 Camera Man <i.like.privacy.too at gmail.com>:

> On 03/28/2014 12:18 PM, cyril poulet wrote:
>  As a matter of fact, I wanted to use them for computer vision, where
>> calculating edge densities and motion estimation are important.
>> Now that these are deprecated, the only way is to first decode each frame
>> then re-calculate MVs and DCTs, which is computationnally costly...
> You probably don't want to use them for computer vision; They are
> specifically optimized for minimizing visual artifacts on one hand, and
> staying within protocol constraints on the other (e.g. some streams have no
> I-frames but do have guaranteed "frame convergence" - which means the
> motion on those is guaranteed to be "wrong").
> It's not that they can't be useful, it's that the MV information is "very
> noisy" compared to what you'd get from computer vision stuff. Doing a
> pyramid Lucas-Kanade (openCV and libccv both have good implementations,
> supposedly) does not require a lot of CPU and provides vastly better motion
> estimation for computer vision.
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