IVTC an m2v w/o re-encoding

[lacto]

I'm unfamiliar with DVD authoring details so don't know if it makes sense to say I don't want to "re-encode," but...

'Sneakers' (R1, NTSC) seems to have been stored telecined on the DVD. Looks fine on my TV of course, but less than optimal on a computer screen and one of these days, in the not-too-distant future, I'd like a projector.

I'm shooting for a DVD-to-DVD conversion where the copy is stored progressive but (other than the IVTC) I didn't have to change any of the data. (Please correct me if I'm wrong, I understand IVTC as a re-ordering, not changing, of frame/field data.) I want the original movie content without it having been piped through a de/re-compression process.

I removed the content I wasn't interested in using IfoEdit then stripped out the video stream as a .m2v file using vStrip. I brought the .m2v into TMPGEnc and selected the frames to keep according to the IVTC guide. I went with the manual method of identifying the discard/keep pattern. (Got lucky with this movie -- only had to adjust the pattern once because of a cut.)

I can save the TMPGEnc project and create an AVI from the .tpr using VFAPIConv, but what would I do with the AVI? The VFAPI pluggin will serve the frame info to an encoding program in raw form and the encoder will then compress the raw info into another format (DivX, ...). I’m pretty sure that's not what I want. Even if my output format is MPEG2 the new frames will be different than the ones I selected to keep (right?).

At this point I'm not sure what to do. I would like to IVTC the .m2v directly into a new .m2v and remux the VOBs. It should just be a matter of removing frames and setting a new framerate, right?

I've scoured the guides here and elsewhere (and will continue to do so) but everything I find seems geared toward dropping the image quality to fit the info into smaller spaces.

I’d appreciate any help on this. Maybe the answer is right in front of me, I’ve read it a dozen times and just need someone to say, Hey, it’s all right here for ya!

Thanks!
Lacto

[mpucoder]

Where to begin - movies are stored in 23.976fps progressive on NTSC DVDs, but they contain flags which produce a 3/2 pulldown in the player. These flags are preserved in the m2v file, so the video appears to be telecined, but in reality, it is not.
If you really want to mess it up, use a program like pulldown.exe to remove the flags. Then, of course, you're stuck with 23.976fps video, which the authoring program will have to reinsert pulldown flags into.
You don't need to IVTC the video, the authoring software should recognize it as what it is. Also, IfoEdit will recognize that the video has been flagged for NTSC and remux it properly, providing all you did was extract it (or transcode with ReMPEG2).

[lacto]

Thanks, mpucoder. I'm not sure what to think now...

When I open either the original VOBs or the stripped-out m2v in DVD2AVI it shows a frame rate of 29.970, a film value of 99%, and the frame type oscillates between interlaced and progressive throughout the movie. When I open the m2v in TMPGEnc I can step through the IVTC process exactly as described in the guide, picking out the interlaced frames, etc. It plays as interlaced on my monitor. Though I knew such beasties existed, I would not have guessed flags to be the culprits here. But, live and learn.

Of course I don't want to mess it up (who ever purposely messes things up?), what I want is for the movie to play back as progressive. I've read enough posts and articles that mention the occasional DVD with telecined source that I thought I'd stumbled on one. But if I don't have to go through the IVTC process then great! So, what do I do?

I tried your suggestion of remuxing the stripped-out m2v with the VOBs and got nothing but sync errors from IfoEdit. I've not touched the m2v - it's straight from vStrip. I'll keep at it though, maybe there're options I'm not seeing.

Thanks again for your help! If you think of something else I can try, a reference I can read, or even a keyword I can search on (the obvious ones haven't been much help) please let me know.

[mpucoder]

Now that (sync errors) shouldn't happen. I'm getting to the point where I need a database to remember everything, but I think I read something about Vstrip m2v files not being quite right. Since I don't do what you described, that's all I can rely on - but IfoEdit also has an extract feature (which is what I use).
If your major concern is the appearance on a computer monitor screen I should tell you that varies depending on the player program and hardware. On most of my computers (especially those equiped with either AIW or hardware decoders) DVD plays as progressive, unless the TV out is enabled.

[lacto]

I didn't find an extract option in IfoEdit, only a strip streams option. Using that resulted in a different set of VOBs and IFOs, when what I was after was just the MPEG2 video file. Hence the use of vStrip. But, maybe that's not really what I wanted after all.

I thought I was fairly well read on the transcoding processes before but the more I research this problem the more aware I become that I've not always been careful with my wording. Also, I may have chosen an unnecessarily difficult solution. Maybe I can do something at the player-end to get the results I want w/o mucking w/ the DVD.

As I stated, all plays great on my TV. Interlaced, of course, because that's the nature of the device. On my monitor the display is progressive, also (of course) because that's the nature of the device. However, on my monitor both H+ and WinDVD display the video telecined (via 3:2 pulldown?) at 29.97 fps.

My primary question: How do I play the DVD at 24fps (or 23.976 fps) w/o the telecining?

That's the question that's driving me right now. I can see the combing effect on the screen. It's too fast for me to actually claim to see the overlapping fields but I can see the resulting quality difference. I have to use tools like Flask, DVD2AVI, and TMPGEnc to actually discern the combing.

My second question is more curiosity driven and geared toward the mechanics of the m2v storage format and how TMPGEnc works. (I've not read the m2v file format specs yet, will search for those soon.) If telecined playback is really the result of flags in the m2v file, I would expect the pulldown pattern to be constant throughout. However, (as I mentioned) there was one place in the movie where the pattern failed and I had to find the "cut point" and permute (rotate) the pattern. Question: why is there a cut point in the movie if it's stored non-telecined?

Thanks for your help with this. Sorry if my questions (phrasing and whatnot) sound ignorant... I'm researching this as tenaciously as possible and am constantly learning. Unfortunately, I'm finding a ton of mediocre references and few that are truly useful. It's slow.

- Lacto

[mpucoder]

My mistake, it's VobEdit that can extract an m2v file.
The only time I notice any "combing" is when the picture is blown up to huge proportions (like 1600x1200), I can view at actual (720x480) resolution, and it looks OK. You may be seeing the result of resizing. But there is no reason for a software player to abey the pulldown flags, since the source and display are both progressive.
Don't get me wrong, NTSC DVDs can also have 29.97 camera source (without the flags), and they can be intermixed. But virtually all movies (not the made-for-TV features) are 23.976 progressive.
Now, as for the sequence changing, that is possible, and usually the result of editting. Each frame of source contains 2 flags that control pulldown, repeat first field (rff) and top field first (tff). These control the generation of the fields (not frames).
The sequence goes like this:
source frame 1 tff=1, rff=0 - this results in 2 fields - T B (which will make up display frame 1)
source frame 2 tff=1, rff=1 - this results in 3 fields (rff set) - T B T (which makes up display frame 2, and half of 3)
source frame 3 tff=0, rff=0 - this results in 2 fields - B T (which is the other half of display frame 3, and half of 4)
source frame 4 tff=0, rff=1 - this results in 3 fields - B T B (which is the other half of display frame 4, and all of 5)
Net result is 5 frames from 4 - T1 B1, T2 B2, T2 B3, T3 B4, T4 B4

If a splice is made the sequence can be disturbed.

[thegeezer]

i have got this program called rempeg because i want to shorten the size of dvd movies and still keep them in mpeg2.
when i rempeg my movie it comes out with no sound and if i try to use the audio transcoder side of it, it just stops a 6% and hangs there forever.
is there a process that will rempeg my dvd and keep the sound all in 1 action.
or can some1 tell me whats going wrong with rempeg

any help would be much appriciated cheerz

[Stabmaster-Arson]

Simple solution to play your dvd movies progressive /23.976. Buy a progressive scan dvd player. They can see the pulldown flags, and ignore them, but not on a TV of course.