KDVD: Convert 24 to 30fps
 

All right. Now we process our video at 24fps, progressive.

However, our output video has to be 30fps for DVD.

How do I re-convert it to 30fps, and keep the new encode progressive?

You don't reconvert anything :!:
You encode your progressive video at 24fps, with :arrow: 3:2 "pulldown" enabled.
That makes it DVD compliant.

-kwag

Alright, that's what I was thinking.

But doesn't 3:2 Pulldown convert 24fps to 30fps by interlacing two frames together?

That being the case, haven't I ruined my progressive image?

There is almost no progressive display nowaday. Except if you are using a progressive player, with a brand new progressive HDMI projector or a plasma screen, you have to interlace your picture before you can see it.

So then, what you're telling me is that Progressive Scan is a farce? Some kind of marketing tool?

For DVD ? Yes I do.
Progressive scan will be used fully with HD formats (HD-DVD or BluRay). It's just the begining then.

Well then does the DVD Hardware eliminate those lines (or frames), or is it up to your television to get rid of the interlace lines on 2:3 pulldown?

That's the part you miss : a television does not know how to display other thing than interlace. You never noticed it, but all what you are watching on your TV is interlaced ;)

Don't be fooled by the artefact (combos) that you see on a PC monitor when watching such interlaced material : monitors are progressive, and that is why you see artifacts !

Now when you say artifacts, are you talking about the imaging noise around edges (JPEG or MPEG Compression) or are you talking about jagged looking lines or edges?

Also, does an LCD Projection or DLP Projection do this same thing?

I mean this :
http://www.100fps.com/distortion2.jpg

DLP I'm sure they are interlaced. LCD I don't know if they are progressive or not. I don't think the low cost ones are.

Sorry about this, now I feel like I am just pushing. But I do have one more question.

I really want to understand all this. I feel like I encode better when I understand what is actually going on during the encoding.

Alright, with DVD2AVI when you decode with Forced Film on, it decodes to 24fps, and there are NO interlaced frames. Now, I am doing the math in my head, if you eliminated the 2 interlaced frames from 2:3 Pulldown in 30fps, you would come up with 18fps. So something isn't right mathematically, unless I am looking at it differently.

Does the DVD Hardware interlace the frames, or is it interlaced on the DVD?

When you ivtc an mpeg from a capture or telecined DVD, you restore the 2 interlaced frames to 2 progressive frames, that is what happens when you use Telecide(). Now every fifth frame is an extra progressive frame and that is why we use Decimate(cycle=5) to elimnate it. The original 30 fps (29.97) is changed because if you remove every fifth frame out of 30 you end up with 24 fps, 30/5=6 and 30-6=24, thus the 24 fps, which is the original film framerate. Most DVD's on the other hand are in 24 fps with pulldown flags added to the mpeg header to tell the DVD player to telecine the mepg's for proper display on an interlaced display.

The main reason why a Pulldon is applied is cause the original movie mostly will be shot at almost 24fps for cinema purposes and a final TV playback will be done under 60Hz circumstancies (NTSC).

@ PAL we do have 50Hz in our Power systems, so a Television does use the 50Hz for displaying 50 fields per second and 50 fields per second do equal 25 frames per second. So we just apply a speedup to reach the 25fps playback.

@ NTSC its more difficult as 24fps are more far away to 29.97 where a simple speedup would cuause the characters acting and speaking like litte "roadrunners". So to playback faster by maintaining the total lenght, we have to ADD fields and NOT full frames as that would end up in jerky playbacks.
So a pulldown does separate the fields, does double some fields at given points and finally does weave the fields back into frames.

In Avisynth:
Reference:
http://home.arcor.de/scharfis_brain/...rlacing/#2.3.1

But a bistream at 29.97fps would end up in a much more bitrate needed encode, not even mention the plus of needed bitrate as its now interlaced!

So thats why NTSC encoders dont apply a Pulldown direktly, but a Puldown "flag"! This flag included in a 23.976 stream does tell the SAP that "he" (the SAP) should do the pulldown in the given manner as shown above before sending the signal to the NTSC 60Hz TV Set.

This stuff have caused a lot of trouble to me lately 8O

I have some retail DVD,"Hollywood" movies,that I demuxed and
remuxed.The DVD are R1,ordered from U.S.

Some of them is reported as 23.976 fps and others 29,97
when I preview the in DVD2AVI/DGIndex.

My question is,should I run the demuxed .m2v file that has
23,976 fps through DGPulldown to get 29,97 fps when playback,or should I leave it as it is?

And what about .AVI? if the avi is 23,976 fps ,I use to encode with
encode mode "3:2 Pulldown when playback" in TMPGenc.

If the avi is 29,97 fps I just encode it as it is.

Am I doing this stuff right,or should I change my methods?

And the main purpose with pulldown is to get films/movies
compatible with the NTSC standards,right?

Thanks
------------

It depends about what you plan to do with this m2v ?

You are doing right.

Yes it is.

Dialhot wrote:
Nothing directly to the m2v,I demux the DVD in order to add
subtitles in my own language.(No, nothing to do with piracy and filesharing if anyone thinks so :roll: ).

After adding subs,I mux everything back together again.

The pulldown flag is included in the mpeg stream. It is not removed by a demux operation. So you don"t have to put it back : it is still there.

So then, if I understand Phil correctly...

the pulldown flag is in the MPEG Stream. Then is the decoder what produces the interlaced frames on your television?

Exactly. :)

-kwag

Dialhot wrote:
Ok.But does the the pulldown flag only work with SAP?

Cause when I playback the remuxed DVD in MPC, the video renderer
filter shows a playback rate of app.23.976 fps.
And previewing the remuxed DVD in DGIndex shows also
23.976 fps.

All that is normal. For DGIndex, this is even a feature ! This is how you can tell that your DVD is 23.976 or 29.970 (interlaced or progressive)*. Few DVD are like this, but there are some.

Remember that the flag is for displaying the stream on a interlaced only display (like a TV). PC monitors are progressive, and if tools like MPC honor the flag, and send an pulled down picutre to the screen, you will see combos !

*Note: I think taht on DGIndex if you set it to "honor pulldown flags" then you will see it as 29.970 and not 23.976. This is a new setting in the last releases.

Yep,tried with "honor pulldown flags",and
it shows 29,97 fps.So the flags are there even in demuxed state.

But when you Honor the pulldown flags with DGIndex, you are getting a source that has 2 interlaced frames.

With forced film, your source (usually) has 24 progressive frames.

So I guess on a progressive scan DVD, is the video encoded at 24(23.976)fps with Pulldown enabled in hardware?

And on a regular DVD, the video is encoded at 30(29.97)fps with pulldown encoded in the frames.

Did I get this right?

Not at all. There is no "progressive" or "regular" DVD. All DVD issued from a cinema movie are encoded in 23.976 and pulled down during playback. Dvd issued from a TV are generallyt be 29.97o trully interlaced.
There are also "hybrid" disc that mix the two but they are rare.

So a true progressive DVD has no interlaced frames in the video at 23.976fps, but will do pulldown to 29.97fps on playback. Basically your player generates the extra interlaced frames.

But on some DVD's, the source is already interlaced the same as 3:2 pulldown. And other DVD's the source is interlaced on every frame.

Does that about cover it?

Actually, these are considered as very bad sources ;)
Fortunally, they are rare.

Yes it is.

I have a dvd which shows up as 20 fps in dvd2avi and 60 fps in tmpgenc. the screen is 16:9. do I encode using the frame rate tmgpenc tells me the video is using. and after use the custom pulldown 20->29.97 fps in dgpulldown? This kvcd is for private use only.

First stop using dvd2avi and go to DGIndex.
Second, you seems to have a PAL source and DVD2AVI is set to "force film". Set it to "None" (or "honnor pulldown flags" in DGIndex).

That's not possible. Tmgenc must be wrong.

It's up to you to tell to the programms what is the correct fps to use, not the opposite. If you don't know the fps of your source, then forget that source.

Just wondering, after all the mucking around with the fps between the two sources, isn't the audio way out of sync now?

How can you fix that?

I have a 25 fps PAL source, i'm trying to turn into a 29.967 fps dvd, the video conversion is done and i'm happy with it, just no idea how to get the audio to sync now.

I'm guessing the answer is to just let TEMPG handle it, and instead of converting them de-muxed, let TEMPG convert the fps of both the audio and the vid and hope it all works out?

I'm kinda tired right now, and confused and new, so i honestly won't be surprised if you say this doesn't make sense, but please help? :?

The easiest way for progressive PAL to NTSC DVD transfers is to

1) encode the video at 25fps but at an NTSC resolution (i.e. n x 480)
2) use DGPulldown on the resulting video and do a 25->29.97fps pulldown
3) author using the pulldowned video and the original audio track

No sync issues and you can use the original audio. Perfectly DVD compliant and easy as 1-2-3.

But does it really works ? I tried once, a long time ago, with DGPulldown 1.0.3 I think, and this doesn't work at all.

No reason for it not to work. What was the problem? The thing you need to ensure is that you use a maximum of 12 frames per GOP, I forgot to mention this.

I've tried what you suggested boulder, and works spectacularly for some conversions, not so well for others. I'm unsure how to check what the min amount of frames in all the GOPs are, though, so don't know how to find out if that's the culprit in the ones that aren't working.

Also, i'm having issues with the ones that are 23.976 fps, so I'm trying to encode it as an NTSC 720 x 480 23.976 fps, with a 3:2 pull down and hoping that the audio synchronizes with it, if you can think of anything else i might be doing wrong, would be greatly appreciated.

Boulder talk about MAX gop length, and you are controlling it as this is a setting of the encoder.

If you are fooling around with AVIs, we cannot help you with that.