Deinterlacing Question

[hizzy7]

Hi Folks,

After my last restoration project (thanks again by the way!), I fell in love with QTGMC for deinterlacing. I have tried using it on other videos, though, and I have found that the frame rate changes on NTSC 29.97 to 59.94. What is QTGMC doing? Is it doubling the frames? What would I use in my avisynth script to counter that?

Thanks again for you help!

hizzy

[enim]

If you post your script, may be some script expert will have a look and assist your further.
I do not have experience with avisynth. I am still pulling out my hairs to tune-up avisynth as a music/midi synthesizer.

[sanlyn]

If you don't know what interlacing is, don't know what deinterlacing means, don't know the pros or cons behind either, and don't know what QTGMC or other deinterlacers do, why are you using it?

Make a copy of QTGMC.avsi and call it QTGMC.txt. Then read the introductory remarks section of that .txt file and browse the .html documentation that came with QTGMC.

https://www.videohelp.com/glossary?I#Interlace,%20Interlaced,%20Interlacing,%20non-progressive
https://www.videohelp.com/glossary?D#Deinterlace,%20Deinterlacing

If you have a 29.972 interlaced video and you bob-deinterlace it by interpolating full frames from each of 2 interlaced fields, you double the number of frames and, ergo, the frame rate is doubled.

[blud7]

Try this.

SelectEven() # Add this line to keep original frame rate, leave it out for smoother doubled frame rate

[jagabo]

Each frame of interlaced video contains two half-pictures -- called fields. They are intended to be viewed separately and sequentially. So your 29.97 frame per second interlaced video is really a 59.95 field per second video. QTGMC() turns each of those half-pictures into full pictures creating a 59.94 frame per second video.

[hizzy7]

Each frame of interlaced video contains two half-pictures -- called fields. They are intended to be viewed separately and sequentially. So your 29.97 frame per second interlaced video is really a 59.95 field per second video. QTGMC() turns each of those half-pictures into full pictures creating a 59.94 frame per second video.

Hi!

What would you recommend to make this DVD compliant? Is 59.94 DVD friendly?

Thanks!

Hizzy

[hizzy7]

If you don't know what interlacing is, don't know what deinterlacing means, don't know the pros or cons behind either, and don't know what QTGMC or other deinterlacers do, why are you using it?

Make a copy of QTGMC.avsi and call it QTGMC.txt. Then read the introductory remarks section of that .txt file and browse the .html documentation that came with QTGMC.

https://www.videohelp.com/glossary?I#Interlace,%20Interlaced,%20Interlacing,%20non-progressive
https://www.videohelp.com/glossary?D#Deinterlace,%20Deinterlacing

If you have a 29.972 interlaced video and you bob-deinterlace it by interpolating full frames from each of 2 interlaced fields, you double the number of frames and, ergo, the frame rate is doubled.

Hi!

I thought QTGMC is a deinterlacer. It helped get rid of interlacing artifacts from my last project. I used it with Srestore.

Thanks!

[jagabo]

What would you recommend to make this DVD compliant? Is 59.94 DVD friendly?

If you source is truly interlaced leave it interlaced. DVD fully supports 29.97i. If your video is progressive with a native frame rate between 19.98 and 29.97 fps you can encode progressive at that frame rate and add pulldown flags.

[sanlyn]

Is 59.94 DVD friendly?

No, I'm afraid not. Here are the DVD specs for PAL, NTSC, and NTSC Film transfers: https://www.videohelp.com/dvd#tech

Your other comments lead me to suspect you might have a different problem. All PC displays will show "interlace artifacts", i.e., PC's don't deinterlace on playback unless you use a media player that deinterlaces during play. If you see these "artifacts" on TV, something is amiss on the TV or the DVD itself. If it's a retail DVD issue, you'd see interlace or telecine effects on a PC but not likely on TV. If it's an improper transfer to DVD from some other source, and you see problems on TV, then something's wrong with the transfer (such as field-blend deinterlacing, which is ugly no matter how it's displayed).

If using something like QTGMC or yadif to deinterlace, there are two ways to restore the original frame rate:

a) re-interlace:
QTGMC(whatever settings)
SeparateFields().SelectEvery(4,0,3).Weave()

b) keep as progressive:
QTGMC(whatever settings)
SelectEven() #-< or "SelectOdd()", whichever looks better)

If the DVD video uses telecine or pulldown, or some odd form of deinterlacing/blending, you have to use other methods.

[hizzy7]

Hi,

I have been given the impression that interlacing is the ultimate evil, so I thought I had to avoid it at all costs. I only see the interlacing when I turn off the deinterlace filters on my media player. Is it preferable to always deinterlace?

Thanks!

[sanlyn]

Is it preferable to always deinterlace?

No.

[hizzy7]

I am sure that this is an VERY dumb question, but can an interlaced video be progressive, too?

[jagabo]

yes, it's also possible for progressive sources to be broadcast interlaced. That can be restored to progressive frames. It's also possible for a file to contain a mixture of interlaced and progressive sequences.

[hizzy7]

What would the Jedi here recommend to use with this clip?

http://files.videohelp.com/u/183506/live%20and%20die.demuxed.m2v

What do you think of:

Mpeg2Source("VTS_01_1.d2v")
QTGMC(Preset="placebo")
Selectodd()

Thanks again!

[jagabo]

http://files.videohelp.com/u/183506/live%20and%20die.demuxed.m2v

What do you think of:

Mpeg2Source("VTS_01_1.d2v")
QTGMC(Preset="placebo")
Selectodd()

No. It looks like normal telecined film. Use:

Mpeg2Source("VTS_01_1.d2v")
TFM()
TDecimate()

[hizzy7]

Hi Jagabo!

If I can ask, how were you able to tell what script to use? What does telecined film look like? I know what interlacing looks like. How does telecined film differ?

Thank you!

[hizzy7]

Oh, here is another clip, if I am learning something, I don't think it's a fixable one.

http://files.videohelp.com/u/183506/karate%20clip.demuxed.m2v

Thanks!

[jagabo]

The first hint is to look at the MPEG video in VirtualDub. When you have a 29.97 fps video, and you see a pattern of three progressive frames, two interlaced frames, repeating over and over you have telecined film with normal 3:2 pulldown. If you apply a bob filter you'll see fields repeating in a 3:2 pattern. Ie, one frame is repeated for two fields, the next for three fields, etc. These can be restore to their original 23.976 progressive frame rate with TFM().TDecimate().

[hizzy7]

The first hint is to look at the MPEG video in VirtualDub. When you have a 29.97 fps video, and you see a pattern of three progressive frames, two interlaced frames, repeating over and over you have telecined film with normal 3:2 pulldown. If you apply a bob filter you'll see fields repeating in a 3:2 pattern. Ie, one frame is repeated for two fields, the next for three fields, etc. These can be restore to their original 23.976 progressive frame rate with TFM().TDecimate().

That is amazing! Thank you so much for the tip!!!!!

[hizzy7]

For the clip I posted in post # 17, does the clip have 4 interlaced frames followed by 1 progressive one? Is that at all possible?

Thanks!

[jagabo]

For the clip I posted in post # 17, does the clip have 4 interlaced frames followed by 1 progressive one? Is that at all possible?

Close. But even that one progressive frame has some light comb artifacts. That video has been through a very bad PAL/NTSC with severe field blending. Possibly twice, NTSC to PAL then back to NTSC. Or maybe very strong temporal noise reducer. Most field blended PAL/NTSC conversions can be restored to the original film frames relatively free of blending artifacts (with Yadif(mode=1).SRestore()). But that one can't because there's too much blending. Some frames are a blend of four different film frames.

[2Bdecided]

I have been given the impression that interlacing is the ultimate evil

A little knowledge is a dangerous thing.

[hizzy7]

Hi Friends!

I am back with another question for you. Is there such a thing as pull down that isn't 3:2? I have a clip here, but it didn't follow the 3:2 rule above. Is it fixable? Here is the clip:


http://files.videohelp.com/u/183506/kidnap.d2v


Thanks again!!!


h

[jagabo]

Is there such a thing as pull down that isn't 3:2?

Yes. Pulldown can be used to output 59.94 fields per second for any progressive frame rate from 19.98 to 29.97 fps. Only 23.976 to 59.94 uses 3:2. 19.98 would use 3:3, 29.97 would use 2:2. 25 uses 3:2:3:2:2 (except for every 500 frames a 3 is changed to 2 to make up for the difference between 60 fields per second and 59.94 fields per second).

[hizzy7]

Hi!

I tried this on the clip from post #23, but it created some weird effect when people moved. It was almost like they seemed to be moving faster at times, or the motion was not fluid.


Mpeg2Source("VTS_01_1.d2v")TFM()TDecimate()

Also, with this clip, I think I'm seeing 3 interlaced frames, followed by 3 progressive, but, at times, I am counting 4 progressive frames. Am I mixed up? lol!

[jagabo]

You'll probably have to change to TDecimate(cycle=6,cycler=1). That will give 24.98 fps. Or TDecimate(mode=2, rate=25). But you should upload a sample of the source.

And you might as well give TFM() access to the d2v file: TFM("VTS_01_1.d2v").

[hizzy7]

Here is a sample, sir!

http://files.videohelp.com/u/183506/kidnap.d2v


Thank you!

[manono]

What am I missing here? All I see is a D2V which is useless. If you want help how about cutting off a chunk using the [ and ] buttons in DGIndex, going File->Save Project and Demux Video, and then uploading the resulting M2V

[hizzy7]

What am I missing here? All I see is a D2V which is useless. If you want help how about cutting off a chunk using the [ and ] buttons in DGIndex, going File->Save Project and Demux Video, and then uploading the resulting M2V

Whoops!! Sorry!!!!

[hizzy7]

Here it is! Sorry for the mix up!!

http://files.videohelp.com/u/183506/kidnap.demuxed.m2v