I have noticed these, too. These should all be from the original video, however; I've seen it in multiple. Yoimiya x Beat had some pretty bad ones on the waves in the background. It's definitely not the interpolation process, but maybe it's somehow related to my hardware, and that's why I'm getting it in the original, too. If anyone can confirm this, I would be grateful.
It's a
bug limitation in some hardware decoding implementation. The original has no such artifact when decoded with software deecoder. If it's in your interpolated video then probably the initial decoding when you did the interpolation is faulty. The only way to fix it is to do the interpolation again with software decoding.
This
bug thing still presents in the latest RTX 40 card...
Edit: it may not be a bug, but a hardware decoder capability limitation. Hardware decoders usually have some constraints of some features (in this case, probably the ref frame number), while the HW decoder API can refuse out-of-capability streams, some programs actually force the HW decoder to accept it, and can sometimes (like this time) result in decoding errors.
In this case, the problematic video streams are of AVC High Profile Level 6.0, as per nvidia documentation said, it should only supports up to High Profile Level 5.1 for AVC, so this video shouldn't be HW decoded, but in tests I did, FFmpeg and MPV will force the HW decoder to decode it.
This approach is probably for better compability, but is not safe enough. I assume that because SW decoder is the default in FFmpeg (mpv is using ffmpeg library), they decided if a user told it to use HW decoder, the user may not happy to see it refuses to do so.
