changefps vs pulldown

[45tripp]

hi,

I have an avi with 23.976 progressive xvid content.
I've been converting samples to mpeg2.
When converting with CCE i get the following:

[45tripp]

the 4 frame sequence I guess goes aa, ab, bc, cc.

Whereas if I feed it with avisynth using changefps()
One gets the below which I suppose is a, b, b, c.

Obviously when freezing frames and looking at them on a pc it's better looking at the below but what's better for encoding, using pulldown or changefps?
for viewing as final product on DVD?

[guns1inger]

Pulldown. Encode as 23.976, then apply pulldown (or let CCE do it while encoding), then author. Your playback hardware will do a much better job at creating the missing frames than you will do in software.

[45tripp]

I suspected as much.

Some encoders produce results like changefps(). (mainconcept)
Drawback?
Should each encoder be able to produce both results? (settings)
Or are you to encode to 23.976 and use external pulldown software for such encoders?

How do you pulldown in avisynth?

ty

[jagabo]

Some encoders produce results like changefps(). (mainconcept)
Drawback?

Choppy video playback.

Should each encoder be able to produce both results?

MPEG encoders -- yes.

How do you pulldown in avisynth?

You don't. It's the MPEG encoders job to add pulldown flags.

[45tripp]

Choppy video playback.

Yea...
made the mistake in the distant past...

MPEG encoders -- yes.

Not used to mainconcept. Didn't realise there was a specific option for progressive,
which has to be enabled for pulldown to be available.
Are all pulldown options equal?
It seems simple enough but would you prefer to have your authoring program flag the
pulldown rather than the encoder?

You don't. It's the MPEG encoders job to add pulldown flags.

All you can do in avisynth is change framerate and convert 23.976 to 29.97 interlaced?
What is assumefps?

[manono]

Hi-

Are all pulldown options equal?

I've never used MainConcept, but if you're asking if 2:3 pulldown is about the same as 3:2 pulldown, then for all intents and purposes, yes. 2:3 pulldown is far and away the most commonly used, though.

It seems simple enough but would you prefer to have your authoring program flag the
pulldown rather than the encoder?

Either do it during the encoding phase, or apply pulldown afterwards using DGPulldown or Pulldown.exe. I do it afterwards. Personally, I'd be hesitant about letting any authoring program do it for me. It's liable to want to reencode the entire thing, since you're feeding it a non-compliant video.

All you can do in avisynth is change framerate and convert 23.976 to 29.97 interlaced?
What is assumefps?

You can do a lot in AviSynth. ChangeFPS, ConvertFPS, or even hard telecine a perfectly good progressive video. AssumeFPS changes the length of the video (and creates out-of-synch audio unless you stretch it) by adjusting the framerate, at the same time keeping the number of frames constant. You know, you could read up on these things yourself, and get the answers more quickly:

http://avisynth.org/index.php?page=FPS

[guns1inger]

I haven't used an authoring tool that applies pulldown. Most I have used refuse to load 23.976 fps source if it doesn't have the pulldown already applied, as it isn't compliant without it. CCE's pulldown seems to be very good, and so far I have had no problems with it. Ditto for ProCoder. But there is always DGPulldown to fall back on if you have doubts or a healthy level of paranoia.

[manono]

I was wondering about that. The authoring programs I use won't take a progressive 23.976fps video either, but I haven't used all that many different ones, so I wasn't sure about some of the others. Thanks.

[guns1inger]

NTSC for DVD is 29.970 fps. That can be either 29.970 actual frames per second - as in NTSC video - or come from pulldown. So you source can be 23.976 with 2:3 or 3:2 pulldown, or it could even be 720 x 480 @ 25 fps, with pulldown applied to reach 29.970. This last option is often used when doing PAL to NTSC conversion. The hardware then takes care of how it should be displayed.

[Pinstripes23]

DVDLab Pro will warn you then do pulldown for you if you import a 23.976fps mpv file into the assets section. I accidentially discovered this when I forgot to run dgpulldown on the file after encoding. I just let dvdlab do it this one time on this file and had no problems with playback. But for the most part I use dgpulldown.

[guns1inger]

That's right - it does. I had forgotten because I just do it as a matter of course long before I get to authoring.

[AlanHK]

I haven't used an authoring tool that applies pulldown. Most I have used refuse to load 23.976 fps source if it doesn't have the pulldown already applied, as it isn't compliant without it.

Actually, MPEG1 at 23.976 is compliant. At least with VCD.

I was converting some VCDs at that rate to DVD.
I couldn't find any way to convert them to 29.97 short of reencoding to MPEG2. Pulldown doesn't work on MPEG1.
Finally I just tried authoring the video at 23.976, converting the audio to 48k as usual. It worked, at least on my player....

[guns1inger]

Even What is DVD, our first point of reference, doesn't mention VCD @ 23.976 being compliant.

As I can't actually stand VCD resolution, I don't encode or author with it, so it's never been an issue.

[AlanHK]

Even What is DVD, our first point of reference, doesn't mention VCD @ 23.976 being compliant.

It's ambiguous. It says "352 x 240 pixels MPEG1 (Same as the VCD Standard)". And 23.976 is supported in the VCD standard. And in practice it does work at least on some players.

Not to disparage, but useful as they are, these pages aren't "official", and the links from it (to mpeg.org) are dead.

As I can't actually stand VCD resolution, I don't encode or author with it, so it's never been an issue.

So reencoding would only make that worse. Short of throwing them away, this seems the best solution.

[45tripp]

You know, you could read up on these things yourself, and get the answers more quickly:
http://avisynth.org/index.php?page=FPS

You assume I'd understand it
I guess I'll have to try them out.

But there is always DGPulldown to fall back on if you have doubts or a healthy level of paranoia.

Paranoia...
Was just asking. I've had pulldown done a few times by dvd-lab.
I guess there's absolutely no difference but as I was talking about the subject I thought I might ask. You never know.

[guns1inger]

There should be no difference. I remember using the DLP pulldown function beck when I started encoding NTSC material. I had no idea what it was for back then. Then along cam DGPulldown, which allowed me add pulldown outside any particular authoring tool, which made the it easier to produce universally acceptable video.

Now I just let ProCoder/CCE do it, and have no problems. I haven't tested the latest HCEnc fully yet, so I don't know if the bugs have been ironed out there. If not, DGPulldown is the perfect solution.

I believe the pulldown done by DLP is sound, so don't be put off.