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View Full Version : deinterlacing to 60fps question


BabaG
16th September 2007, 23:46
i'm taking some video i've worked on (shot on video, not from
film source) and have been playing with some of the techniques
described on the 100fps website; essentially using avisynth to
separate the fields and send this image to vdub as 720x240
at 59.94fps. it's then interpolated back up to 720x480 using
Gunnar Thalin's 'deinterlace - smooth' filter. this produces 60fps
full frame video. my question: can this be played out from a
dvd to a digital display like an hdtv screen? if i wanted to make
the file portable, how would i do this?

the images are for art shows and would likely display in an
installation context so being able to send the file burned to
dvd would be good. would this be something an mpeg2 file
and settop dvd player could handle? can mpeg2 do 60fps?

what would be a good alternative if this type of dvd
scenario is not practical?

the main thing i find makes these images look good is the
progressive conversion so decimating to 29.97 would
maybe be an acceptable alternative. could someone
recommend a process for how to take 60fps down to 30fps
without recombining into fields or blending two frames into
one? details and links much appreciated, this is not my forte.

thanks,
BabaG

foxyshadis
17th September 2007, 05:04
The information on 100fps is pretty out-of-date; still a good introduction, but the state of the art has advanced a long way along with the processing power able to work with it. For real-time high quality bobbing, avisynth has yadif, tdeint, and a newer smoothdeinterlace, no need for virtualdub, which is very limited in its ability to process interlaced material. This is especially useful in combination with ffdshow, which has a direct interface with avisynth. Alternately, graphics cards also come with powerful deinterlacing now, but it's tricky to get them to work.

DVD is naturally 50i or 60i. There's no way to get full 50/60p, but then again, most CRT TVs can't do that anyway, and on PC most DVD playback software will bob it (double-rate) rather than same-rate deinterlacing, as will LCD TVs. It generally won't look as good, they tend to have a lot of vertical jitter unless they can use the newer graphic cards' power. To get an interlaced stream from a double-rate one, you need to use this avisynth snippet:
SeparateFields().SelectEvery(4,0,3).Weave()
This will give you TFF video.

If you do decide to go the 30p route, and aren't concerned about realtime, you can use any of avisynth's bobbers and simply use SelectEven() afterward. Besides the fast ones (tdeint, yadif), there are very slow ones (securebob, mvbob, mcbob). More can be found by searching the avisynth forum.

Try making a short DVD, see if interlaced encoding is sufficient for your needs, and if not, you can always use 30p instead. You can put either on a DVD, just remember to choose whether or not it's interlaced when you encode.

jjoshua2
19th September 2007, 05:01
I just did some deinterlacing with the 100fps method. Could you detail a process for your favorite highest quality (in your opinion) way? I am recoding to 320x240 as well.

foxyshadis
19th September 2007, 11:18
By which method? There are several on the site. The highest quality methods are mvbob and mcbob, both of which are motion-compensated deinterlacing, but they're also by far the slowest. A sample script is really nothing more than

include("path\to\mvbob.avs")
mvbob()

Since they take care of most of the finicky bits. The main difficulty is just gathering all the required plugins, but I think there are packages. However, if you're shrinking to QCIF, you really don't need that kind of extreme quality, probably, and can get away with Yadif or TDeint, which are pretty balanced speed/quality. Both have plenty of examples in their docs.

2Bdecided
19th September 2007, 13:45
Just burn your original 60i footage to DVD.

Or take a PC and play the 60p footage directly from that. The only advantage is the possibly superior deinterlacing in the PC.

However, if you use a decent TV, or a decent upscaling (HD/)DVD player with the 60i content, the deinterlacing is probably good enough. Cheap TVs and cheap "progressive" or upconverting DVD players don't deinterlace that well.

FWIW I've been taking HD, and converting it to 1024x576p50 (PAL country) and it looks better than normal 720x576i50 - especially the chroma. You can only play it on a PC though.


As foxy said, lots of people drop to 30p or 24p as part of a film-ish look. You can put both onto a normal DVD and watch on any TV. Beware motion judder.

Cheers,
David.