Blackmagic Forum

Hi!
All three deinterlace methods give me strange artefacts on the DV material:



It seems that artifacts take place in uncontrast areas with quick moving parts.

Try uploading the images again and describe each one.

I see artifacts that look identical to this, deinterlacing HDV 60i -> 60p using all three methods in Resolve Studio 17b6. It doesn't happen in all cases, but the first where I noticed it is a quickly moving person against a background of breezy trees (which does seem like an algorithmic nightmare to me, but FCPX deinterlacing and ffmpeg yadif both handle it okay).

It appears and disappears in alternate frames (leading edge one frame, trailing edge the next, then back to leading edge). I've got a clear zoomed-in video export but I dunno what will happen if I try to upload that, so have a screen grab instead:

It's the dreaded chroma subsampling error. Your source is probably DV, right?
QTGMC is handling that better, and I'm just about to test the new beta of VEAI, which has de-interlacing now.

De-interlacing is a complex science!

Yup, HDV. Just confirmed still the case in beta 7.

Try Video Enhance AI, they now have a de-interlacer too. I didn't see same chroma artefacts there, but instead there are some soft shadows between contrasting areas of fast moving objects. Well, as the famous Yves Faroudja once said (after working on it for decades): "de-interlacing doesn't work"…

I got excited about 'improved deinterlacing quality' in the tweet announcing Beta 8, but same behavior.

I do notice that this happens when I'm deinterlacing from the original HDV, but not when I'm deinterlacing from the same video exported to ProRes still interlaced, which supports the theory that it's a chroma subsampling issue.

I'm pretty sure about that, it looks exactly like some TVs with faulty chips did years ago.