Pulldown etc. in dvd2svcd dvd to dvd R's

[peclark]

I thought I understood progressive and interlaced, but now I believe I am very confused. confused. I am using dvd2svcd to make dvd backups to dvd+r. I have read conflicting information. When you use bitrate viewer, etc. most dvd's show as progressive frames. But I understood that progressive films are stored as interlaced material so analog tv's can play them and progressive DVD players use deinterlacing chips to make progressive frames for digital tv's. So are dvd's progressive source and dvd player interlaces them for analog tv's? Or are they stored interlaced and dvd player deinterlaces for digital tvs? Another question is when you use dvd2svcd or others for film dvd's and it does the pulldown, is the movie stored on backup disc as 30 or 24 fps. If it is 24 fps, then there isn't any reverse pulldown for the dvd player to do? And if it is stored as 24 fps, does the dvd player than convert to 30 fps for analog tv's? I have a progressive dvd player, but it doesn't say in manual that it does 3:2 pulldown, but I assume this is a given with progressive players. Thanks

[r6d2]

Hi, peclark, and welcome to the forum. You will find a way out of confusion by reading some guides too, but in short, this is it:

Movies are shot at 24 fps. NTSC movies are converted to 30 fps, interlaced, by a telecine process. DVD2SVCD uses DVD2AVI to tell if the telecine originally applied can be reversed by another process called force filming. Then it encodes progressive at 24 fps. The pulldown process then sets some flags on the output stream in order for the player to apply these flags and produce an "interlaced on the fly" picture on the TV.

You can encode the movie as originally interlaced too, but you will likely get a lower quality because more frames must be encoded and then your limited BR is allocated sub-optimally.

When force film is not possible, DVD2SVCD attempts to run a process called IVTC, which is sort of the same as force filming but applying mere brute force.

This (http://www.doom9.org/ivtc-tut.htm) guide may be useful to get the insights of the matter. It is not trivial at first, but you'll get closer to the subject by reading through it.

[peclark]

Thanks, that clears some things up. I have been a lurker on this site for probably a year making svcd's. Now I have a DVD burner and just got a Toshiba 57 digital TV. So the flags tell dvd player to convert 24 to 30 fps and progressive back to interlaced? How does dvd2svcd encode as progressive? Does it take the interlaced from dvd and deinterlace it depending on deinterlacing mode you select in Conversion tab. I have it set to No deinterlacing and I usually have Progressive frames checked in Advanced area of Encoder tab. So am I backing up as interlaced at 24 fps? I have a sub $100 progressive dvd player and in a forum for Toshiba tv's I have read to feed it in interlaced mode from player because my tv's deinterlacing is supposedly better than most dvd player's (my TV's options are for 480i it converts to 1080i and for 480p it converts to 540p or 1080i. If the dvd player does convert 24 to 30 I assume it only does that when in interlaced mode on player and not progressive so the 3:2 pulldown feature on the player is a moot point for dvd2svcd backups. If I do encode as interlaced and send it that way to my tv, my tv does the pulldown. Now I need to find out if best for dvd2svcd to encode as progressive or interlaced, like I said I am not sure what I have been doing given my settings. Thanks a lot for help. The fog is starting to lift. On a side note I remember a few months ago I encoded a Farscape episode. Force film or IVTC was not triggered. When playing on my old analog tv at that time I could see the interlaced effects. I saw it had 2 frames interlaced and 3 progressive and I reencoded and forced IVTC and it looked fine then. But I could never figure out why it still didn't look ok encoding as original without IVTC.

[peclark]

After reading guide a bit, maybe I misunderstood your post. I think when you said dvd player does "interlaced on the fly" is that it converts 24 to 30 for analog tv's and not that it takes progressive frames from dvd2svcd encoding and interlaces it? With my dvd2svcd settings I believe for film dvd's my backups are interlaced 24 fps. And you will only get 24 fps progressive if you have dvd2svcd do deinterlacing, which you should only do if you watch them on computer/digital tv and your computer software or dvd player or TV doesn't do its own deinterlacing. Am I correct or still missing it? :eek:

[peclark]

Hmmm.. I think I have it wrong. I remember reading once that dvd players can't take progressive frames and do interlacing, but that is probably wrong. Does the force film/IVTC process only convert 30 to original 24 or does it also convert interlaced back to original progressive frames? If thats true then deinterlacing only is applied to true video interlaced source? I get confused when hearing the progressive players have deinterlacing chips to display progressive frames, so I took that to mean film interlace back to progressive involves deinterlacing and reverse telecine only is reversing fps to 24.

[r6d2]

I see you're still confused. :) But don't despair. It is not a trivial matter.

My advice is you don't get into trouble, keep it simple. If you are encoding an NTSC movie, DVD2SVCD will do the work for you. Select Auto in field operation. Don't deinterlace. IMHO the movie will look better if you let DVD2SVCD encode it interlaced if neither force filming nor IVTC worked.

Read the guide again, and again. Then reread your posts and see if you can answer your own questions, which you seem to be doing already. Come back afterwards if you have any more questions, but don't ask us to requote the guide here. :)

My advice is: Do your homework and feel proud at the same time by learning a tough subject! ;)

[peclark]

Thanks, I read some more guides and I think I have it mostly figured out now, like you said earlier dvd2avi gives you a 24 fps progressive backup with flags for dvd player to convert to interlaced 24 fps if not in progressive mode. I understand now there is a differece between film deinterlacing (reverse telecide) and video deinterlacing (blending, etc. fields). BTW, even though a Toshiba TV forum says to set player to interlaced, when I slow down movie, I can definetely see some jaggies in interlaced mode that I don't see when player set to progressive. Also, the resolution screen on Avia disc looks much better.

[r6d2]

Originally posted by peclark
like you said earlier dvd2avi gives you a 24 fps progressive backup with flagsYou mean DVD2SVCD, right?

You may try to remove the Pulldown step alltogether, which may look tricky at first sight but IIRC there are some posts about this you can search.

My player, for instance, plays 24 fps and interlaces on the fly with or without the pulldown flags. I really don't see much point in this as a general rule, since it saves only time and not space, but it might (just guessing here) avoid some "jaggies" problems on your player.

[manono]

Hi-

Mind if I comment? Everything that r6d2 has said is correct, and although you're slowly getting it, you're not all the way there yet. But as r6d2 also said, it's tough to get a handle on this subject.

I may be repeating some things that r6d2 said. Whenever possible, you want your NTSC SVCDs or DVDs encoded as progressive 24fps. This is particularly true if you're outputting to a progressive display (as you are). Not only will you have the same number of bits being distributed among 20% fewer frames resulting in better quality video, but you'll be free of the artifacts associated with displaying interlaced material. And by running pulldown after the encoding process, you'll have the flags set to output 30fps (really 29.97fps, or even more really, 59.94 fields per second).

All NTSC DVD players output 30fps, either by following the flags set during the Pulldown stage, or by just outputting 30fps material as stored on the DVD. However, if you have a progressive scan DVD player, combined with a progressive display (as you do), then that 30fps material, originally 24fps film sourced, and stored on the DVD that way, can then be converted back to 24fps. Yes, it is done in 2 steps-first 24fps progressive on the DVD to 30fps interlaced, and then back to 24fps progressive. All those review places call what's being done deinterlacing, and that's real confusing, as well as being incorrect for 24fps progressive material. Some of them call it more properly 2:3 (or 3:2-synonymous, sort of) pulldown detection. Or in terms that we, as encoders, are more familiar with, it runs a Force Film or IVTC on the material to get it back to 24fps.

Getting that 30fps telecined material back to 24fps can be done either in the DVD player, or in your display (your HDTV). If your player is sub-$100 as you said, then, as you read, it probably is better to do it in your TV, particularly if your TV has a Faroudja deinterlacing chip built into it. In that case you'd set the player to output 480i, and your TV will convert it to 480p. You'd have to turn that feature on for your TV. In mine, it's called Film Mode. Cheapo progressive scan DVD players have cheapo deinterlacing chips. Material properly encoded as progressive can be handled just fine (it runs a simple Force Film-reads the flags to get it back to 24fps). But if you're watching some poorly encoded anime, for example, it'll give your DVD player fits, and the chances are good that you'll notice the interlacing from time to time.

Want some more reading material? There's a pretty good and easy to understand explanation of what's going on right here on this site, with Robshot's Article (http://www.doom9.org/synch.htm). And for a really in-depth look at the subject, try This Article (http://www.hometheaterhifi.com/volume_7_4/dvd-benchmark-part-5-progressive-10-2000.html). Some of that article was written a while back. At one point they say, But sources which are truly progressive in nature are hard to come by right now. And that's no longer true. Almost all Hollywood-type movies are properly encoded these days. That wasn't always true, and it's not yet always true of DVDs produced by smaller companies, or of imported DVDs, or many DVDs made from "foreign" films. And it's with those that a good "deinterlacing" chip, whether in the DVD player, or in the HDTV can make a world of difference.

[r6d2]

Originally posted by manono
All those review places call what's being done deinterlacing, and that's real confusingVery good point, manono. I took me quite a while to understand the difference when learning this stuff.