IVTC ???

[Ripper2860]

I've determined that a DVD I wish to convert to SVCD is telecined. I will be watching the SVCD only on a regular interlaced TV (non-HD, non-progressive). Do I need to run an Inverse Telecine (IVTC) process or is that really only needed for proper display on a PC or progressive scan TV?




Thanks !!

[fmctm1sw]

On a TV, I'd do it. Telecined material looks jerky on my TV when there is side to side movement (and top/bottom) but that's less noticeable.... I need to save off a small clip because I harp on this every time I see it. I'll make a note to do it this weekend...

[pijetro]

For your situation, the main advantages would be better compression during encode, and 2 less frames out of every 5 to encode...

If you leave it as is, then that's okay too.. Since it was made to display originally for what you're viewing...

Good luck!!

[FOO]

When it plays it will be telecined. You are asking for trouble
if you IVTC .

[pijetro]

Yeah, but Foo, if he runs Pulldown.exe on the .m2v file, I can't see there being a problem..

Whatddya think??

[lordsmurf]

Waste of time when playing on tv. Plus IVTC is not perfect.

[fmctm1sw]

I sense a debate coming....

[lordsmurf]

On a TV, I'd do it. Telecined material looks jerky on my TV when there is side to side movement (and top/bottom) but that's less noticeable.... I need to save off a small clip because I harp on this every time I see it. I'll make a note to do it this weekend...

I'd like to see this.

[FOO]

I've seen quite a few videos that
are mixed 24 30 or have non uniform pulldown sequences.
and if you edit it , you are sure to disturb the sequence.

I've had enough problems to be wary of it.
If it's from a NTSC FILM video you don't have to IVTC anyway
it's already progressive , and can be re-encoded like that

[SLK001]

First off, I doubt that your DVD is hard telecined (why don't you tell us what the source is so we can confirm this).

Second, a properly telecined video looks normal on a TV. If not done properly, then it will look lousy. Remember that you have been watching telecined material all of your TV viewing life, and there is very seldom a complaint of "jerky" video. Anyway, fmctm1sw, you recommend that he IVTC his video because of "jerkiness". The last process that he will need to do is telecine the material again. You got it right, but for the wrong reasons.

Third, there is the opportunity for having higher bitrates (or less space needed) with a proper IVTC. But you encode 4 frames out of 5 (not 3 out of 5).

Fourth. Trouble from IVTC'ing? Not if it is done correctly. There are filters that will IVTC quite accurately.

Fifth. I can assure you that performing an IVTC is definitely worth the effort. Without the one extra frame out of every five, this action alone will allow you to encode at a bitrate about 20% higher than if you don't IVTC. Either that, or you can pack more video on your disc.

I sense a debate coming....

No doubt.

Sixth. Videos that the FOOmeister is refering to are called hybrids. These are by far the most difficult to IVTC. Fortunately, they are not that common (unless you are doing TV shows with CGI in them - like Star Trek TNG, or Enterprise). For most peoply, hybrids are better off left as hard telecined products.

[j1d10t]

Videos that the FOOmeister is refering to are called hybrids. These are by far the most difficult to IVTC. Fortunately, they are not that common (unless you are doing TV shows with CGI in them - like Star Trek TNG, or Enterprise).

I've been capturing Enterprise for about a year now, and never run into a "hybrid" episode - they have all had the same, standard telecined pattern of 3 progressive 2 interlaced, and I've preformed IVTC on all of them, without any problems... (Well, OK, I had problems when I first started, but that was because I was still learning how to IVTC)

I use VirtualDub to do the IVTC, and it's been working fine. I've run into other shows that have had a "hybrid" TC issue, but not Star Trek.

[SLK001]

I don't do these episodes, so I was just guessing about Enterprise. I have heard that ST-TNG is definitely a hybrid offering.

I imagine the these hybrids would even give the studios headaches.

[dphirschler]

Put me in the camp that suggests you try inverse telecining. It's well worth it. And it is not so hard. The 3:2 pattern rarely changes (unless you dropped a lot of frames while capturing).

I just recently wrote my own manual IVTC function in AVIsynth. It's easy to get synched with the pattern, easy to identify the pattern change points, and easy to correct for pattern changes. Chances are you will not have to correct for pattern changes more than you have breaks in the video such as disc changes or commercials (or dropped frames).

Give it a try. The benefits far outweigh the costs.


Darryl

[j1d10t]

I've done some (less than a dozen) of TNG's episodes, as well as some DS9 episodes, and so far I haven't run in to any that are hybrids, but maybe I've just been lucky so far

[SLK001]

Instead of a completely blind IVTCing process in AVISynth, I recommend Donald Grath's DECOMB filter. If you use the "High Quality" modes of TELECIDE and DECIMATE, you can get near 100% accuracy.

I did a 130 minute movie from a laserdisk capture over the holidays and I have yet to find where the decisions made by this filter were incorrect.

[SLK001]

I've done some (less than a dozen) of TNG's episodes, as well as some DS9 episodes, and so far I haven't run in to any that are hybrids, but maybe I've just been lucky so far

Look at the scenes where there is definite CGI. These CGI scenes were created in interlaced video at 29.97fps, while the normal scenes with people were shot in film at 24fps. The film part was telecined, then the CGI parts were merged into the final product. This is my understanding of how these eps were made.

[dphirschler]

Yeah, Decomb is great. I use it all the time. But I wrote my own function because of decomb's failure. It usually does a great job, but for some reason Star Wars confused it.

I'd be interested in checking out some Star Trek episodes. I've read before that they are hybrid, and it just seems stupid to me. I'd like to see it for myself. What would be the reason behind that? The CGI renders would take longer, you would have to edit video instead of film frames (which seems more difficult). I mean if you are hell bent on editing video instead of film, why not shoot the whole thing in video?


Darryl

[j1d10t]

Look at the scenes where there is definite CGI. These CGI scenes were created in interlaced video at 29.97fps, while the normal scenes with people were shot in film at 24fps. The film part was telecined, then the CGI parts were merged into the final product. This is my understanding of how these eps were made.

If they are (and granted, I haven't examined each and every frame), then I must have had a happy accident, and lucked out on my IVTC (and I don't think I do anything special when I IVTC), because they've come out smooth on playback.... I can't see even a slight jump, or jitter.

[Ripper2860]

Thanks for all of the replies. This has certainly become a very informative thread.

Here is some addtional info ...

The DVD is a Music Video -- Eagles: Hell Freezes Over. It appears to be a pattern of interlaced and non-interlaced as follows: PPP-II-PPP-II-PPP, etc. I assume that this is a telecined video that was originally FILM and is now NTSC.

Again -- my intent is to convert to SVCD and play on a standard NTSC/interlaced TV.

[SLK001]

That pattern is the standard 2:3 pulldown pattern for telecined material. For putting on an SVCD, I would IVTC it. This would buy me a higher bitrate.

[j1d10t]

I agree with SLK001 - IVTC whenever you can. It saves bitrate, or gives you more bitrate per sec, so you get a better picture....

If you're not comfortable with AVISynth, try VirtualDub to IVTC it - there is a good guide on this site about how to do it.

[fmctm1sw]

Remember that you have been watching telecined material all of your TV viewing life, and there is very seldom a complaint of "jerky" video. Anyway, fmctm1sw, you recommend that he IVTC his video because of "jerkiness". The last process that he will need to do is telecine the material again. You got it right, but for the wrong reasons.

You know, I did think about that a while back. I was thinking, "why do my vhs tapes not do this when I play them?" I don't have the answer to that (maybe I just never noticed it), but I did notice one thing about a movie I was testing last night. Telecined material will have a flickering effect when I play it on my PC. An example of this is an overhead shot of a building (like from an airplane or something). As the camera moves, the windows will flicker. I noticed I can stop that by doing an IVTC. I don't even have to decimate, it will look better with just the telecide() command. I'll tinker around more this weekend....

[j1d10t]

but I did notice one thing about a movie I was testing last night. Telecined material will have a flickering effect when I play it on my PC. An example of this is an overhead shot of a building (like from an airplane or something). As the camera moves, the windows will flicker.

That's because your computer monitor is progressive, and your TV is interlaced.

If you play a telesinced MPEG file in a software DVD player (like PowerDVD), it will automatically de-interlace it, removing that "combing/flickering" effect you are seeing.

[fmctm1sw]

That's because your computer monitor is progressive, and your TV is interlaced.

If you play a telesinced MPEG file in a software DVD player (like PowerDVD), it will automatically de-interlace it, removing that "combing/flickering" effect you are seeing.

Understood, but I watch the stuff on TV mainly, and it flickers there too. I only use my PC to make sure the audio isn't totally out of whack and things of that nature.

[SLK001]

...I watch the stuff on TV mainly, and it flickers there too. I only use my PC to make sure the audio isn't totally out of whack and things of that nature.

Are you saying that your VHS tapes also flicker on your TV? I'm assuming that the answer would be "no".

A properly applied 2:3 pulldown will not result in the flickering that you noticed. The persistance of the TV's phosphor will ensure that it doesn't happen. Also, remember that the video also plays faster (each frame only plays for 33mS as opposed to 41mS). It could be the settings that you are using for your pulldown.

Also, the software players will not deinterlace the video, but they will remove the telecining (or just not apply a pulldown), and play the video at it's original 24fps frame rate. However, if your video is hard telecined, then it will be displayed "as-is", and at the display rate of 29.97fps.