On Fri, Jan 29, 2021 at 2:01 AM pdr0 <p...@shaw.ca> wrote: > Mark Filipak (ffmpeg) wrote > > I've never heard of "optical flow errors". What could they be? (Got any > > links to > > explanations?) > > The artifacts in your video are optical flow errors :) > > If you've ever used it - you'd recognize these artifacts. There are very > common > > > > There are about a dozen prototypical "fail" categories or common errors > that > plague all types of optical flow > > These are errors either of motion vectors, or object flow (object > boundaries > or "masks"), occlusion errors. > > Internet is full of examples, explanations. The topic is rather large, just > search google, there is lots of info. If you have a specific question then > ask. > > Sometimes you get clean interpolated frame results; but sometimes there > are > massive distracting errors. It varies by situation and sources. > > Your example has one of the common categories of "fail" where there are > repeating patterns and textures. It falls under the "Picket Fence" fail . A > prototypical tracking or dolly shot by a picket fence, or brick wall will > come up with interpolation errors > > The peripheral edges error are common because there is less data beyond the > periphery of the frame, for n-1, n+1 and the motion vectors are less > accurate compared to the center of the frame > > Another common one is when objects pass over another. The flow masks aren't > perfect and you end up with blobby edge artifacts around objects > > > > > > > > >>...For artifacts around frame edges, letterbox edges usually some form > >> of padding is used. I don't think ffmpeg minterpolate has those. > > > > I've done that. The result was just okay. The slight riffling on the > frame > > boundaries during camera > > panning isn't all that objectionable to me. It occurs to me that > > minterpolute could queue frames and > > look 'forward' to later frames in order to resolve boundary macroblock > > artifacts -- afterall, it has > > the motion vectors, eh? > > Some algorithms can use N-3, N-2, N-1, N, N+1, N+2, N+3, I don't think > minterpolate can. More is not always better. Often you get more > contamination with a larger "window" > > Sometimes just changing the blocksize can produce better (or worse) > results. > The problem is ffmpeg minterpolate is soooo slow, and you have no usable > preview. Some of the other methods mentioned earlier do have previews - so > you can tweak settings, preview, readjust etc.... > > Why you ignore fact that libavfilter also allows usable preview and readjust of parameters.
Amount of false information propagation here is astounding. > > > > > > > > > -- > Sent from: http://ffmpeg-users.933282.n4.nabble.com/ > _______________________________________________ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
