25fps (50i) - 23.98 fps conversion

Author: DVD-BOY
Date: 18-Oct-2005, 9:47 AM

Author: DVD-BOY
Time: 18-Oct-2005 9:47 AM
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Oh sources of video wisdom!

If I capture in a 50i PAL Video source, which was originally based on a Feature Film, what is the best technique to create a new progressive encode?

I'm assuming I have to somehow slow down the (de-interlaced) captured file, and then encode the file out with 2:3 flagging so that I ultimately get a 29.97fps file with 3:2 pulldown.

This will only work if the film has been produced from a sped-up film source, and not if the content has gone film > NTSC > PAL ?

Many Thanks for any pointers!

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Author: Moth3r
Time: 18-Oct-2005 10:54 AM
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If your video is standard PAL-film, and assuming your capture drivers don't get the wrong field order, then your 50i capture will be 25 progressive frames per second.

Put simply, my recommended technique is thus:

- demux the audio, and slow it down to 960/1001 (~95.904%).
- write an AVISynth script that resizes the 576 vertical resolution down to 480, and changes the framerate to 23.976 fps.
- encode the script output with CCE as an NTSC DVD - this will make an MPEG-2 file with 2:3 pulldown flags inserted to give an effective framerate of 29.97.
- mux, author, etc. as usual.

There is an alternative method which involves keeping the framerate at 25fps, and then using DGPulldown to set flags to output 29.97fps. This means no adjustment to the audio is necessary. I would check out Doom9 for details.

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Author: DVD-BOY
Time: 18-Oct-2005 4:31 PM
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Thanks Moth3r, I'll let you know how I get on - never done any AVISynth scripts, so that ought to be fun for starters

What do you reccommend for the audio? Is Soundforge up to the task?

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