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View Full Version : CCE: how to PAL > NTSC and keep same length


afterdub
10th September 2006, 22:15
I'm encoding a 25fps PAL .avi file of 49 minutes to NTSC. I read the excellent CCE 2.70 guide. It says

If you want, you can change the framerate of the source by checking one of the options in the Frame rate area. ...
In case you select 29.97 fps, the Inverse 3:2 pulldown option will become active.

When I do this, I get a file of 41 minutes, according to DVD-Lab. What am I doing wrong?

Another question: when I encode at a 25fps rate, the output plays fine on my dvd player. Do I really need to worry about converting to NTSC any more?

Thanks for your help.

Skelsgard
10th September 2006, 23:18
Another question: when I encode at a 25fps rate, the output plays fine on my dvd player. Do I really need to worry about converting to NTSC any more?
Is it possible that your player is PAL compatible? Wich will eliminate the need to transform to NTSC...

afterdub
10th September 2006, 23:42
Apparently my player can handle PAL. But, having blundered into that realization, I'm still left wondering how to do the conversion properly. Did I misunderstand the Guide article?

Skelsgard
11th September 2006, 00:45
If you want, you can change the framerate of the source by checking one of the options in the Frame rate area. ...
In case you select 29.97 fps, the Inverse 3:2 pulldown option will become active.

1) when u change the framerate, the file is gonna change its duration. 49 minutes at 25 fps will play for 41 minutes at 29.970. So u did nothing wrong there. It would be different if u had "converted" the framerate from 25 to 29.970.
2) About the Inverse 3:2 pulldown option, I think it means it will be active for selection, as opposite of being greyed (not selectable), in case u intend to use it.

Anyway, if your player is PAL compatible, then u donīt need (and I recommend u against it) to convert to NTSC.

afterdub
11th September 2006, 01:16
Thanks, I see what you mean by the difference between changing and converting.

In looking around more, I've ended up in the VirtualDub universe. Apparently it's not possible to do this without introducing some choppyness that you then have to use Avisynth filters to take care of. Or so it seems.

manono
11th September 2006, 13:15
Hi-

When I do this, I get a file of 41 minutes, according to DVD-Lab. What am I doing wrong?

Quite a bit. You speeded it up. If you also speeded up the audio by the same amount, you're close to having chipmunk or helium voices. You should have slowed it down to 23.976fps.

I'll back up though. There are 2 good ways to do the conversion. One is to resize to 720x480 and slow it to 23.976fps, slowing the audio as well. When done (or during the encoding) you apply pulldown to output 29.97fps.

The other good way is not to change the framerate at all. You resize to 720x480, but keep the 25fps framerate. The audio no longer needs to be slowed down as the video length stays exactly the same. When done you use DGPulldown with the Custom Box checked for 25->29.97fps to output 29.97fps for NTSC. Both ways are best accomplished using an AviSynth script file for frameserving. And don't forget to uncheck "For DVD" at the top of the CCE main screen.

Assuming the PAL source is progressive, there's no choppiness when done right.

afterdub
11th September 2006, 20:24
Thanks, Manono.
It sounds like you're referring to the procedure at http://neuron2.net/dgpulldown/dgpulldown.html:

A typical workflow is as follows (assumes you are starting with PAL source material):

* Demux the video and audio streams.
* If the video is interlaced, deinterlace it to make it progressive. If it is already progressive, skip this step.
* Resize the video to 720x480.
* Encode the video to MPEG2 at 25fps progressive.
* Run DGPulldown on the video MPEG2 stream to flag it up to 29.97fps (using the 25fps --> 29.97fps conversion).
* Mux the audio and video into a program stream, or author a DVD using the audio and video streams.

I'll take a shot at it later, it sounds like an easy flow right into DVDLab. Bunches o' thanks to you all.

manono
12th September 2006, 03:00
Yes, you have it. The only thing I might qualify is the bit about deinterlacing. Be darned sure it's really interlaced before you go around messing it up with a deinterlacer. That means actually having a look at the frames, and not relying on something like DGIndex to tell you. The vast majority of PAL DVDs have been encoded as interlaced and are reported as such by DGIndex. However, the vast majority of PAL movies on DVD come from progressive sources, and do not need deinterlacing. There's a big difference there. If you don't see interlacing lines upon examination of the frames, don't deinterlace.