Resolution x Deinterlacers

[acrespo]

I am usually capture with 640x480 then deinterlace with TomsMoComp (-1,5,0). I tried capture with 720x480 yesterday and deinterlace process is better than in 640x480 source.

There are a resolution rule to get better deinterlacers performance?

[toysoldier]

thanks for your experience�B
I want to ask "deinterlace with TomsMoComp (-1,5,0)" is better
than decomb511.dll?
about capture resolution please looking for guru "trevlac"'s postes.

[trevlac]

Beats me if Tom's Motion Compensation does better on a larger frame or not. I don't know what it really does. Don't even know much about deinterlacing ...

However, here is a comparison writeup by a real 'Guru' who writes deinterlacers.

http://neuron2.net/journal/journal.html


My Guess... Deinterlacers interpolate. Depending on how they do this, there may be less bluring in 720 vs 640. Your eyes and experience are your best guide. You can use what people say to help you decide what options to test, but look for yourself is the best policy. ;)

[pelmen]

my understanding has always been that deinterlacing works best when the captured file is precisely the same height as the source signal. Otherwise either hardware or software interpolation can take place before the deinterlacing can take place.

depending on your intentions deinterlacing may not even be the best idea. if your are for example turning your vhs collection into dvds then keeping it interlaced as per dvd spec would be desirable. even on progressive scan displays some deinterlaced content can look worse or jumpy since deinterlacing is really a destructive process (ie you are losing video information). but if you're just looking to dump to avi/qt/rm etc files to store on cdr or whatever then deinterlacing is one of the least destructive things the video will be subjected to :)

bottomline: test and experiment. if a different technique/setting seems to make a visible improvement then go with it :) test with something precise and short like a movie trailer from a dvd (rip the trailer, dont record the analogue) and then you can easily frame step to an identical frame in each of your test runs and visually compare them to see which ones look clearer, less smeared and without the fringing issues some deinterlacers will produce. choose a shot with plenty of movement of course to test.

[Wilbert]

my understanding has always been that deinterlacing works best when the captured file is precisely the same height as the source signal.
There is a difference between height and width :)

[bb]

Originally posted by Wilbert
There is a difference between height and width :)
Indeed there is. To avoid misunderstandings: pelmen is right; the height is more important, because changing the height means destroying the interlaced structure.

bb

[drcl]

if you must deinterlace use a smart bob like dgbob from the aformentioned Guru Donald Graft or an area based deinterlacer which is almost the same thing.

as for horiz res; I read a hugely technical discussion about ntsc resolution(I tink it was on arstechnica) and it came to the concusion 640 is the optimum - for reasons i cant even begin to explain. it seems any higher and you are merely picking up signal noise which is not improving the picture.

[trevlac]

Originally posted by drcl
as for horiz res; I read a hugely technical discussion about ntsc resolution(I tink it was on arstechnica) and it came to the concusion 640 is the optimum - for reasons i cant even begin to explain. it seems any higher and you are merely picking up signal noise which is not improving the picture.

What do you mean? 640 is optimum for deinterlacers? Would you would be so kind as to post a link? I'd like to read the thread.

If you are speaking of signal noise -- you must be referring to the bandwidth of a frame.

For practical purposes, I think one should capture at their desired output ... keep at or above 480, and avoid resizes. DVD=720, PC=640, SVCD=480. All NTSC of course. And if you make VCDs ... well, VHS is better. :)

This would mean that post processing (like deinterlacing) would be done at 720 for DVD output and 640 for PC output. But I have no basis for saying 720 looks better than 640. However, 640 resized to 720 is worse than 720. Just as 720 resized to 640 is worse than a 640 cap. As far as detail goes.

[acrespo]

I did some tests with 640 and 720 sources. My conclusion is best to deinterlace at 720. My tests include Decomb, TomsMoComb and AlignFields. All did a perfect job at 720 but at 640 I see some residual combs.

Now I am capturing at 720, deinterlace and resize to 640 to final video. Anybody have some comments about it?

[drcl]

i think the discussion was specific to bt cards of I wouldn't have read it and it wasn't specifically about deinterlacing. It was merely about horizontal res in ntsc capturing inducing noise above 640. I'll see if I can find the source.

[Arachnotron]

It is not clear to me if we are talking about VHS tape here or broadcast (or another analogue source). That would make a huge difference for the outcome, since broadcast can have up to twice the horizontal detail of a VHS tape. (depending on the country you are in)

For VHS I would not expect much difference between 640 and 720 (none at all actually)
For broadcast in PAL country on the other hand...

Another thing I don't get is why this would be better specifically for deinterlacing. I would expect the higher resolution to be better for any filter, and even for the raw capture.