Interlaced and Progressive Video in one MPEG2?

[MYoung]

With DVD, is it possible to mix interlaced and progressive video in one VOB? I'm trying to put together some stop-motion animations. I have some that are 14.985fps and recently I concluded that making my animations at 23.976fps would be better since my camera is progressive. That way, on a progressive display the image wouldn't be deinterlaced through BOB and softened.

I figured the way to go was to telecine the 23.976fps, progressive video to 29.970fps and just cut it in with my interlaced video portions that I have. But in TMPG I don't know how to get it to make an MPEG2 that will know when to do BOB or 3:2 pulldown in the same video -- that is, if it is even possible to have progressive and interlaced video mixed into one video. I thought it was possible through selecting "3:2 pulldown" in the "encode mode" part of TMPG.

I know it's possible to just create different "titles" and link them in DVD-Lab, but that creates a slight delay as it switches titles. I'd hate to go that route if there is a more streamlined way of doing this. Any suggestions? Thanks!

[adam]

Whether the video is stored at 29.97fps interlaced or stored at 23.976fps with pulldown flags (which instruct it to be played back at 29.97fps) its viewed as 29.97fps by the dvd authoring software.

In TMPGenc enable the 3:2 pulldown during playback option under encode mode on the video tab and set output framerate to 23.976fps. You should then be able to author DVDs with 29.97fps and 23.976fps material in the same title.

If you have already encoded to 23.976fps, you can use pulldown.exe to add the pulldown flags to your video stream.

[MYoung]

Hmm, I'm still not understanding...

So, say I have 2 AVIs -- 1st clip: a minute of 23.976fps progressive video; 2nd clip: a minute of truly interlaced (like from a low-end interlaced camcorder) 29.970fps video.

In that case, how do I go about encoding those videos together into the same title? I cannot simply join them as AVIs because they have different frame rates. So what I thought I should do is telecine the progressive video using this code...

AssumeFrameBased
SeparateFields
SelectEvery(8, 0,1, 2,3,2, 5,4, 7,6,7)
Weave

Then my 23.976fps video is now 29.970fps (and can be joined with my other, truly interlaced video), though when the telecined video is played back on a progressive display, the player needs to do inverse-telecine on it so that intelacing lines aren't seen. Am I totally thinking about this wrong?

[MYoung]

Well, I think I got it to work. I dunno if I did it optimally. Here's what I did: I encoded the progressive and interlaced video portions seperately. Then I joined them using TMPG's MPEG Tools. Does that sound like the way to do it? I checked out the video properties in PowerDVD and it was a beautiful thing to see it tell me it was doing bob on my native interlaced video and weave on my progressive! Thanks for pointing me in the right direction, Adam! I've been scratching my head for a long time on this one. Hopefully I found the proper solution. We'll see...

[racer-x]

Why couldn't you just put both videos in the same Tittle in DVD-Lab, then have the 1st video connect to the 2nd video when it finnishes? There would be no delay in the transition.

[adam]

If you must encode them as one stream than yes there is no way getting around a hard telecine, which is physically encoding your first clip to 29.97fps. But as racer-x noted this is not necessary with DVDs since different cells can be linked seamlessly. You can encode the one clip to 29.97fps, encode the other clip to 23.976fps but add pulldown flags, and then link them together in the same title and they can playback seamlessly.

I don't use DVD-Lab so I have no idea of its limitations. For true seamless playback you would need to set the link to seamless, but if racer-x is right than it can do this just by putting both clips in the same title. The framerate of the clip, as far as the authoring software is concerned, is determined by the rate at which it plays back. A 23.976fps clip will playback at 29.97fps as long as you have the pulldown flags enabled. So if you simply enable them than you can author both of these clips in the same title. This is in fact what is done on the vast majority of NTSC DVDS. The opening logos are 29.97fps and the movie is 23.976fps and they are linked together seamlessly.

[racer-x]

It's very simple really. Just go in the Connections window and use the Draw Connections Tool to link the two clips. When the 1st ends, the 2nd will start.

I have linked as many as 9 videos for my last music compilation DVD this way with no problems whatsoever.

[MYoung]

racer-x, do you mean doing something like this? ...



If so, I'm pretty sure that is really just making 2 different titles that are linked. The link between two titles is not seamless -- there is a slight studder in audio and video. DVD-lab doesn't seem to allow me to put more than one video track per "movie" (I think movie => title in DVD-Lab). I need a seamless connection.

Are there any consequences to just "joining" the MPEG2s using TMPG's MPEG Tools? The join looks to be seamless, but I just worry that their might be audio sync issues for long files. Then again, if my audio is dealt with seperately as one big wav, then maybe there wouldn't be a problem.

My preference would have been to do a hard telecine of my progressive video (using the AviSynth script I referenced previously) and joining that to interlaced clips (again, using AviSynth), then encoding that huge scripted AVI instead of joining MPEG2s, but whatever works I guess. I just couldn't seem to get TMPG to do whatever it needed to do to specify the hard telecined footage to be IVTC'd when played back on a progressive display. I probably had the wrong TMPG options for doing that. I hope that makes sence.

[duhmez]

Join them with tmpgenc before authoring. problem solved. A telecined video will merge fine with a true 29.970 video. (I am assuming of course that you have already applied 3:2 pulldown)

Do know, if you will ever want to edit from this finished dvd, it will be a pain beause you won't be able to force film in dvd2avi once a hybrid source like this is used, it will fugger up

[adam]

If you really want to hard telecine in TMPGenc then set output framerate to 29.97fps on the video tab, and set output to interlaced (non-progressive.) On the advanced tab enable the 3:2 pulldown filter. Note that this is entirel different than the 3:2 pulldown while playback option on the video tab, the one on the filter actually performs a hard telecine.

There are two disadvantages to hard telecining your video and joining them. First is that hard telecining "can" substantially lower quality. You now have 20% more frames, which requires substantially more bitrate to offset. If you have a high bitrate then this is not a problem though. A larger problem though is that you are encoding interlaced fields rather than progressive frames. This is inherantly harder to encode, and pretty much all encoders do a poorer job of it. Again, using a high bitrate will offset this quite a bit though. So, in reality you may not even notice a quality difference, but technically this is a lower quality route to take, and in my opinion its much more work to do, and it definitely takes more time.

Now the second problem. Joining mpegs can be messy business. Doing so often does cause sync problems, usually in the clip(s) after the join point. Of course if it plays ok then there is no problem.

Assuming your DVD authoring software allows seamless links, there is no reason to take the route you are taking. But I'll have to leave it to racer-x or someone else to determine whether DVD-Lab can do this, since I've never used it.

[MYoung]

duhmez,
Yeah, I joined them before I authored and it works fine, though I need to assertain if I'm going to have sync problems. If not, I think this is the way I'm going to go because I'd certainly not edit the MPEGs when I have the sources in uncompressed AVI. Thanks for the advice.

adam,
Thanks for the explaination! That puts some of the puzzle pieces together for me!

racer-x,
Thanks for the advice too.

I'll just have to try these routes and see what yields the best result.

[MYoung]

Not to beat this horse to death but...

If I hard telecine in TMPG than the AVI that I perform that hard telecine on has to be entirely 23.976 fps, right? So if I did that I'd still have to join that resulting MPEG2 with any native interlaced MPEG2s OR join them in the authoring phase, in which case I'm just better off not doing the hard telecine and having TMPG do its 3:2 pulldown when playback because it takes up less space and encodes better, right?

But...

If I hard telecine my progressive clip using AviSynth and join it with another native interlaced AVI, resulting in a so called hybrid AVI that is part hard telecined and part native interlaced, then what encoding options in TMPG would be correct for allowing the resulting encoded MPEG2 to IVTC the hard telecined portion and BOB deinterlace the native interlaced part on playback? Or is there even a way to do that?

[duhmez]

If you really did hard telecine with avisynth, then all you would do is encode interlaced and make sure you check the field ore first. no other filters. IVTC is what you do when you are de/recompressing, your source is 23.976 already so tmpgenc won't do it for you. Now however you do it, via pulldown or hard, simply join the mpeg2 files when done and play them. if they are in sync all the way through, then you can be confident they will remain in sync after you make a DVD out of it.

Your "hybrid" avi is merely a 29.970 avi, with the 3:2 pattern, and the interlaced section remianing interlaced. you would get the same effect by hard telecining right in tmpgenc.

Encoding 23.976 and applying pulldown will get you the best results quality and size wise. If audio sync issue crops up when you join them, then author them with a program that wil let them seamlessly play one after another without a pause, and then sync won't be an issue.

Is there a reason why you don't want to just encode interlaced instead? Looks best on a tv that way. if you do want to bob or something, bob using avisynth filters before it gets fed into tmpgenc, then encode both clips progressive and add pulldown to first.

[MYoung]

I did the hard telecine and joined them and encoded as interlaced, but the problem was that that I saw interlacing lines when it was played back in PowerDVD. Shouldn't those hard-telecined frames have been reconstructed in realtime back to progressive frames by PowerDVD? That's what baffled me. But as you said, it sounds like doing the 3:2 pulldown on playback or authoring them together is a better idea for size and quality issues.

The reason I just don't encode interlaced is because I want to offer those people with progressive displays a treat! Besides, I own a sweet high-def CRT projector and I gotta go progressive with that!

Thanks again!

[duhmez]

Maybe powerdvd has to have a manual setting to deinterlace? Ive not watched interlaced content with powerdvd before.

In any case you know what you have to do. Enjoy.

[MYoung]

You know, maybe I just wasn't understanding what PowerDVD is supposed to do in the case that is has hard telecined video to display. It IS deinterlacing the hard telecined video (applying bob). So I'm not seeing horizontal lines (I know I said otherwise before -- my bad). What I am seeing, however, is motion blurring from interlacing lines being deinterlaced by bob.

Now... if I hard telecine then is bob the proper behavior for a progressive player (like PowerDVD) to be doing on the video? I figured that on the fly IVTC was the proper behavior as that way there would be no motion blurring from bob deinterlacing. But maybe I had that misunderstood from the beginning.

[SLK001]

If you HARD TELECINED the video, then you will ALWAYS have the interlace lines. When I first read your initial post, I thought that you were trying to combine 29.97fps video with 23.976fps video This is done all the time, but just insure that the FILM portion has the correct 2:3 pulldown applied before joining, so the whole thing has a 29.97fps.

I was imagining that your 29.97 part was true 29.97 (ie, captured from live TV), and not just a hard telecined film clip (if so, then REMOVE the telecine with a IVTC filter).

I am also not sure about what you mean here:
"That way, on a progressive display the image wouldn't be deinterlaced through BOB and softened. "
This doesn't happen.

As for your 14.985fps part, it would be a simple thing to convert it to 29.97fps at the expense of double the frames.

All in all, I guess that I am still confused about what you want to do.

[MYoung]

I am combining 23.976fps video with 29.97fps video. I just wanted to combine them as AVIs as opposed to combining them as MPEG2s, that way I wouldn't have to worry about sync problems.

The problem that I'm having is that when I hard telecine my 23.976fps video to 29.97fps video, join it with my native interlaced 29.97fps video (as a big 29.97fps AVI), and then encode it to MPEG2, when it's played back on a progressive player and progressive display I can see motion blur that wouldn't exist if progressive frames were being reconstructed on the fly. Instead, it's applying bob deinterlacing to the whole video, including the 23.976fps content that I hard telecined.

However, when I encode the videos seperately -- as 23.976 fps with 3:2 pulldown on playback (29.97fps internally) and join that with the 29.97fps native interlaced material, all is fine -- no motion blur (as for the progressive portions of the video PowerDVD does weave, not bob).

I know I'm probably not taking about the terms correctly. I'm still very much a newb at this stuff. Thanks for the patience and help! I really appreciate it!

[SLK001]

You will see the lines on hard telecined videos on a progressive computer screen. You won't see them on a TV, because the persistance (of the phosphers) is much longer.

Anyway, PowerDVD doesn't BOB deinterlace. BOBing is taking one field and creating a frame by interpolating between the lines (or you lose about half the detail).

Two MPEGs with properly sync'ed audio joined together should result in one MPEG with properly sync'ed audio.

[duhmez]

3:2 pulldown removal during playback would be the ideal method, but of course with hard telecining it will display every frame, and every 2 out of 5 is _very_ ugly on progressive display.
hard telecine=very bad, very bad indeed!

[lordsmurf]

I think the short answer to the question is "NO". The MPEG-2 must be encoded the same. That is not to say however, that they cannot be placed back-to-back in the same VTS/Track ... easily done in TMPGEnc DVD Author.

[vmesquita287]

MYoung,

This is possible, but the only encoder I know that supports this feature is CinemaCraftEncoder SP 2.6x. You have to feed 29.97 interlaced/telecined video and check the 3:2 box. It will detect 3:2 pattern and do IVTC when needed, and will encode interlaced when it's the case.

[MYoung]

Dang-nam! The SP version is just a BIT outta my budget range, where BIT = $1900.

Hey lordsmurf,
The method you described, do you think that's the same as connecting two movies/titles in DVDLab? Because I know that does not result in a seamless connection in DVDLab -- the audio and video both studder at the connection. Then again, DVDLab is not TMPGEnc DVD Author. Using TMPGEnc DVD Author, would such a back-to-back placement (of encoded MPEG2s, right?) in the same VTS/Track be seemless? What are the limits to the number of back-to-back placements you can have?

[lordsmurf]

I did this a while back on 5 videos in one VTS. It was seemless to me. Try it at least. The program is free to try. Author from it and then playback in PowerDVD to see for yourself.