Inverse telecine & 3:2 pulldown

[Shadowmistress]

I'm thoroughly confused and I can't find a decent guide for this. My goal is to convert several avis to 23.976 with pulldown and fit many of them onto one dvd. My reasoning is that I figure I can squeeze a bit of extra quality out of them for the space alotted using a higher bitrate compared to 29.97fps. If this works correctly, I'll be converting all my future mpgs to 23.976.

My problem is that I'm a total newb when it comes to telecine and tmpgenc settings and I'm having trouble classifying my source video(s). Any help would be appreciated as I'm trying to build a foundation of understanding here.

The Source
Right now I have 15 avis and 39 mpgs all with the roughly the same attributes:

When I load one of these avi's into tmpgenc, it defaults to 30fps instead of 29.97 though. Any avi or mpg that I load will always change back the framerate to 30fps regardless of what I'd set it at when I first open the file(s).

Question 1: Can you add pulldown to divx? Could these files already have it?

When I look at these frame by frame in tmpgenc's inverse telecine filter I see 1 frame with interlace lines after 1 frame without. In other words, all my (a) pictures are clear and all my (b) pictures have lines. (Yes I checked really thoroughly and that's the pattern.) But on playback they're hardly noticable.

Question 2: Is this an interlace source or progressive? Do I have to worry about fields?


The Conversion
Now considering this is a 30fps/29.97fps (whichever) source and I'm trying to convert down to 23 then back up again with pulldown, tmpgenc is behaving really weird when I open the file and just tick the 3:2 pulldown box. I open it and it shows 30fps. In the video tab I change that to 23.976 fps. Then I tick the 3:2 pulldown. When I look back at fps I see tmpgenc has changed that automatically to 50fps.

Question 3: Is that right? Has tmpgenc set it correctly? I don't want to convert all my files only to find the audio has gone out of sync or the pulldown doesn't work after I burn them. And I won't really know by just playing them on computer, right? (No, I don't have any DVD-RW on hand.)

Question 4: Should I be ticking inverse telecine to shrink it from 30/29 to 23fps instead of changing the framerate under the video tab? If that's the case, what 'setting method' and 'deinterlace' options should I be using for my (a) (b) pattern? And does this work on a progressive source as well?

Question 5: If the answer to the above question is yes and I convert using inverse telecine, can I set the 3:2 pulldown flag as well? What I mean is can it all be done within one encode using just tmpgenc or are the two settings cancelling eachother out?

Question 6: When this file is finally converted properly, should it report that it has 23.976 fps or 29.97? How on earth can I tell whether the 3:2 pulldown has already been applied to an mpg file?

Question 7: Will PowerDvd play 23 fps correctly even if I've screwed up the pulldown or will it show me if I've messed it up? I know WMP will just play any framerate without fuss so that's not going to be any help. But does PowerDvd accept true film sources without protest or warn me by stuttering the video? (I tried playing raw 23 fps on my dvd player and the video just stuttered.)


So, can someone give me a method to this madness please?

[FulciLives]

Just about any downloaded DivX or XviD is progressive. A progressive 29.970fps source CANNOT be telecined back to 23.976fps. It just cannot be done.

Sorry.

- John "FulciLives" Coleman

P.S.
Chances are the source was VIDEO and VIDEO footage at 29.970fps cannot be reversed telecined to 23.976fps anyways which is probably why the DivX/XviD was encoded progressive 29.970fps

[Shadowmistress]

All right, so my source is progressive. That's what I initially thought anyway but got confused. I understand why it can't be telecined so I'll drop the idea of reconstruction.

Now forgetting about quality for a moment and talking purely about saving disk space, is there any way I can still convert to 23fps and use pulldown flags just to get it to play in my dvd player without stuttering? I realize it will drop frames and lose quality, but a smooth 23fps is preferable to me just for the size savings IF it plays right in my dvd player. (Hell, I could even go as low as 14.985 if my dvd player would play it.) So can fooling the player be done using 3:2 pulldown?

Otherwise, I guess I'm looking into converting to pal with an ntsc resolution

[manono]

Hi-

If it's supposed to be 29.97fps, then there's no way to get it to 23.976fps without dropping unique frames and making it play jerky. Applying pulldown later won't help in the least. If it was supposed to be 23.976fps originally, the original ripper was incompetent, and there's no way to get it back to 23.976fps at this point and have it play smoothly.

For that example you posted, I have a feeling the original encoder was an idiot anyway because he resized to 352x240 which is 1.47:1, so I think he just resized down the NTSC DVD to quarter resolution without taking DAR into account. In addition, you say you see some interlacing lines when going over it in TMPGEnc, and since 240 is half of 480, he could have gotten rid of the interlacing by just saving every other field and then resizing only along the horizontal axis, rather than doing a straight resize. Make any sense? The point I'm trying to make is that for that sample anyway, the encoder messed it up completely, and prevented you from taking it back to 23.976fps, even if that's the original framerate. Maybe some of your other examples are encoded better than that one was.

[Shadowmistress]

Hi manono

I'm not looking to avoid dropping unique frames - in fact I have to and I know it. But there's jerky and then there's stuttering. Let me explain.
If I took this file and dropped the framerate to 15fps in the video tab, yes I might notice some jerky motion during high motion scenes but it will play back relatively smoothly in WMP. Mostly, I don't notice it and don't mind that particular framerate. But there's a big difference if I try to play it on my dvd player though because it looks like the picture snags and freezes every few frames, then continues to sync itself with the audio. (I'd done tests on it with mpeg-1 on vcd using 12-23fps a long time ago.) In fact, it looks like it plays the 12-23 frames at the 29.97 framerate then runs out of frames to play and just pauses until the start of the next GOP where it syncs again to the audio only to freeze again until the next GOP. The audio plays uninterupted. This is what I call stuttering and this is what I'm trying to get around by fooling the player.

Now I imagine most dvd players only understand the two framerates, 29.97 and 25, so I'm actually wondering if I can use the cheat 3:2 pulldown offers to my own advantage and save disk space. At this point I don't know how it will look - it may not even be worth it in the end - but I just want to know if it can be done at all even if it looks like crap.


Everything you said in your second paragraph went completely over my head. I can tell you that all the files are the same resolution and have the same (a)(b) pattern and that they all look like they've been taken from VHS (so they kinda look like crap anyway which is why I don't mind messing with them further.)

[jagabo]

I'm actually wondering if I can use the cheat 3:2 pulldown offers to my own advantage and save disk space. At this point I don't know how it will look.

Creating 23.976 fps from a 29.97 fps source will be done by dropping every 5th frame. You will see small jerks every 1/5 second when you play it back on the TV.

The interlace comb lines you saw on the IVTC dialog of TMPGEnc appear because the program is showing you every combination of fields to help you figure out the pulldown pattern. IVTC can create interlaced frames (in addition to making a jerky result) if you apply it to a progressive 29.97 fps source.

[manono]

There's no question that storing 23.976fps with pulldown provides better and more efficient compression than storing 29.97fps. But at what price? Do you really want to purposely create jerky playback? If it's already progressive 29.97fps then there's not much you can or should do, I don't think.

You mentioned possibly getting it down to 15fps by knocking out every other frame. If your end goal is DVD, the lowest framerate you can apply pulldown to is 20fps (19.98fps), and you'll need DGPulldown to do that.

So, if you really want to knock out as many frames as possible from your 29.97fps AVI and still create a compliant DVD, then Decimate(3) in an AviSynth script will do it for you. Or you can ConvertToFPS->19.98 in VDubMod before frameserving, if that's how you do it. Maybe there's a way to do it directly in TMPGEnc. I don't know as I don't use it. Then when the encoding is done, run DGPulldown for 19.98->29.97 and it'll flag it properly. It'll play jerky, but shouldn't stutter the way you described before.

[FulciLives]

IVTC can create interlaced frames (in addition to making a jerky result) if you apply it to a progressive 29.97 fps source.

I did not know this ... good to know.

Although I know enough NOT to try an IVTC on a progressive 29.970fps source

- John "FulciLives" Coleman

[Shadowmistress]

So, if you really want to knock out as many frames as possible from your 29.97fps AVI and still create a compliant DVD, then Decimate(3) in an AviSynth script will do it for you. Or you can ConvertToFPS->19.98 in VDubMod before frameserving, if that's how you do it. Maybe there's a way to do it directly in TMPGEnc. I don't know as I don't use it. Then when the encoding is done, run DGPulldown for 19.98->29.97 and it'll flag it properly. It'll play jerky, but shouldn't stutter the way you described before.

Yes, this is what I want to do but I didn't know if it was possible. 20fps? Really? That's pretty cool! Ok.... but I've never used any of the programs you mentioned. I have virtualdub 1.3 - never used mod, don't know scrap about scripts, and frankly, DGPulldown is virgin territory for me.

Most of this stuff - especially what jagabo wrote - hovers just beyond my understanding threshold. Will VdubMod work with mpgs as well? If I just convert using tmpgenc to a regular 20fps and then use DGPulldown, is that the same thing? Anything I should know about DGPulldown since I've never seen the software before?

By the way, I'm planning to author with dvdlab pro afterwards if that makes a difference.

[mikiem]

FWIW in hopes it might help...

"if I try to play it on my dvd player though because it looks like the picture snags and freezes every few frames, then continues to sync itself with the audio. (I'd done tests on it with mpeg-1 on vcd using 12-23fps a long time ago.) In fact, it looks like it plays the 12-23 frames at the 29.97 framerate then runs out of frames to play and just pauses until the start of the next GOP where it syncs again to the audio only to freeze again until the next GOP. The audio plays uninterupted. This is what I call stuttering and this is what I'm trying to get around by fooling the player. "

To me sound like more of an encoding, media type problem. That said...

At 352 x 240, a lot of the original picture has already been thrown out, which was made worse unavoidably using high compression (DivX). Most of the stuff like telecine, IVT, Pulldown etc is intended to work with the original full frames, so you're limited to anything that might help, might work for you with minimal time/effort & max quality.

You might want to check here: http://www.thedigitalbits.com/officialfaq.html
One option to save space on a DVD is *not* to enlarge to 720, leaving that to the player. Using that option, shouldn't have to bother with fps etc.

If you do want to cut fps, you can just drop frames, or you can re-render. As posted already, if the source was film at 24 p, extra frames (fields really) were added. When it's played back, we see *ghost* images that fools us into seeing smooth motion. Sizing the frame to 240 basically screwed up those ghosts if you see stuttering.

More inteligent filters rely on detecting telecine and interlace in fields which aren't there anymore. Dropping frames by doing a by-the-numbers IVT, hopefully the frames that were added to get 29.976, are the ones that will be removed, & you'll lose the stuttering. THe hopefully part is because sometimes they use different patterns adding frames and fields, and your ivt pattern might not match the original.

Re-rendering OTOH should create new frames based on averages from those before & after. Vegas, particularly with it's supersampling, can do a good job of this, but it's a hefty render time, & frames will look softer on your PC.

Maybe something there will help. Myself, I'd probably just try running the worst scenes through IVT in V/Dub, trying both the manual types of IVT listed, & see what it looks like. Might try the Avisynth routines too. Then I'd burn a couple of short clips to DVD RW, both small and enlarged to see the quality difference, if there was one -- I've done a lot of SVCD that looks about as good as DVD, but never tried VCD resolutions at all.

Good luck

Edit: adding this on as trivia really... IVT can operate like some deinterlace filters, looking for artifacts to blend or eliminate, or it can just blindly conform to a pattern -- results vary depending on how a particular IVT routine works. With any of the blind type filters, ones that don't attempt to analyse frames, you can sometimes get improvement where by definition they shouldn't work at all -- all you can do is try a short test clip and see, and results will vary, probably with each video.

[jagabo]

After thinking about this some more -- I don't think you can use any type of pulldown on a 352x240 MPEG file. I think you would have to increase the vertical frame size to 480. But that gives you twice as many pixels to encode. So any savings you get from a lower frame rate would be offset by the larger frame size.

I think you should just encode as MPEG2 at 352x240, 29.97 fps. I ran a quick experiment with a Xvid (~750 Kbps, VBR), 320x240, 29.97 fps, progressive, AVI file. I set TMPGEnc to encode with Constant Quality at 65 percent, 352x240, 29.97 fps, progressive. The resulting MPEG file had an average video bitrate of 1362 kbps. The final file size for the 25 minute episode was 323 MB (even with 384 Kbps audio). You should be able to fit a dozen half hour episodes on a DVD with setting like that. Do you really need more than that?

[adam]

There's no correlation between framesize and storing video at 23.976fps internal (pulled down.) You can do this with 352x240 mpeg2 on a DVD just fine, I do it all the time. VCD, which of course only supports 352x240/288, supports 23.976fps natively and doesn't even require pulldown flags. The player performs the telecine automatically.

[jagabo]

There's no correlation between framesize and storing video at 23.976fps internal (pulled down.) You can do this with 352x240 mpeg2 on a DVD just fine, I do it all the time.

You are right. I just tried it and it worked properly.

I still don't think converting a progressive (probably blend or drop field deinterlaced) source to 23.976 fps just to save on bitrate is worth the loss of fluid motion. Although ShadowMistress may not mind the jerkiness since she doesn't mind 15 fps video!

[manono]

Hi-

I have virtualdub 1.3 - never used mod,

I have Mod and no longer use VDub. If you know how to frameserve using VDub, then have a look in Video->Framerate->Framerate Conversion and check if that same Convert To FPS is available.

Using DGPulldown is easy. Load your encoded MPV in it, tick the "Custom" box, fill in 19.98 and 29.97, uncheck the 2 boxes that come already checked, and hit "Convert". It'll spit out an M2V when done, ready for authoring.

[Shadowmistress]

VCD, which of course only supports 352x240/288, supports 23.976fps natively and doesn't even require pulldown flags. The player performs the telecine automatically.

Does DVD support 23.976fps natively? What I mean is that I intend to keep the resolution at 352x240 but author it as dvd with several episodes of course. Would I still need the pulldown?



I tried converting to 19.98 with tmpgenc but I got screwed on the filesize. The GOP defaults to I P pictures only and what I save in frames I lose in crunchability of B pictures so that 19.98 turns out to actually be a bigger filesize than 23.976. (I maxed out picture spoilage.)

Currently I'm doing tests on the 23.976 with pulldown on cd-rw by making mini dvds to see what plays in my player. I'll let you know how it goes.

[adam]

No the DVD standard does not support 23.976fps natively. Are you talking about putting multiple 23.976fps VCDs onto a DVD? If so yeah that's a problem since I don't believe it is compliant and converting to mpeg2 or up to 29.97fps will lose quality. I'm sure lots of players will autotelecine it just fine though.

But if you are talking about using anything else as the source just use mpeg2 instead of mpeg1 and keep it 23.976fps with pulldown flags. Its not like the flags take any extra work to add, or affect quality in any way. Just always add pulldown flags whenever you encode mpeg2 at 23.976fps.

[jagabo]

The only difference between a 23.976 fps MPEG2 file and a 23.976 fps MPEG2 file marked for 3:2 pulldown are the few bytes per GOP that specify the 3:2 pulldown pattern.

Standard definition NTSC television sets only accept one input format, 59.94 fields per second. So whether you use 23.976 frames per second without 3:2 pulldown flags and the DVD or VCD player automatically performs the pulldown to make 59.94 fields per second, or 23.976 frames per second and explicitly add the 3:2 pulldown flags to create the 59.94 fields per second, the final result on the TV screen will be exactly the same.

[adam]

Except that 23.976fps w/out pulldown on a DVD is not compliant and not all DVD players will perform the telecine. My apex is like this. Without the pulldown the playback is noticably jerky, it basically stops completely every couple of seconds. I've seen this happen on several other players as well.

I agree that as far as the NTSC tv is concerned its 29.97fps or nothing but sometimes you can't get there without the pulldown flags.

[jagabo]

Yeah, I didn't mean that there was no difference in terms of DVD, just that there was no difference in the file (and hence the file size as you pointed out) except for the pulldown flags.

My player can play just about any MPEG1 or MPEG2 file on an ISO data disk. 24 fps is a little jerky because it simply repeats every 4th frame.

ShadowMistress -- you might try that. If you don't need pretty menus, just burn some MPEG file onto a data DVD and see if your player plays them. The behaviour may be different than when playing movie DVDs.

[Shadowmistress]

I need pretty menus. I'm a hard-core Dvdlab fan.

I tried burning 23.976 on VCD a while back and my player stuttered them. I didn't know about pulldown then. (I'm not even entirely sure DGPulldown works quite right with MPEG-1's. Dvdlab accepts mpeg-1 but it gave my some weird GOP results. But to be fair, I was trying to author a dvd with them.)

I can't wait to get Blue-ray.
I've not been keeping up on the news. Does anyone know how much a player costs, how much a burner costs (if they even have them available yet) and how much disks go for?