Reversing PAL speedup.

[rcavanah]

OK, so there are a few threads on this, but most of them are about 10 years old so I'd love to know about modern methods.

I'm working with some progressive PAL source material, which I can tell has been sped up from 24fps to 25fps. I have some 23.976 source that I want to cut in with it, so the best course of action for me would be to revert the speed back down to its original film speed and, of course, slow the audio as well; I can do this manually, but if there's a one-shot method that's great. I DO want to reduce the pitch with it, because the source is higher-pitched than it should be. One portion of this project may involve slowing 5.1 audio though, dunno if that's more difficult.

Also, I dunno if this requires using a pulldown in the file for rendering to DVD, but oftentimes Vegas doesn't display pulldown properly for editing, so if there's a way for me to get it all to 24p(?) and then put the pulldown flags on after editing, that'd be ideal. Or maybe I don't need the pulldown at all; I dunno. Not gonna be widely distributed, so wide compatibility isn't an issue. I'll also be rendering an AVCHD version, for whatever that's worth.

I'm wondering about the easiest way to do this. It's 1080p, so no resolution conversion necessary. So, in short, what I'm looking for is the slow-down method which doesn't remove or duplicate frames, but simply changes the speed and length of the video. I've never used AVISynth scripts, so if that's a part of it, I may need a simple explanation.

[poisondeathray]

OK, so there are a few threads on this, but most of them are about 10 years old so I'd love to know about modern methods.

I'm working with some progressive PAL source material, which I can tell has been sped up from 24fps to 25fps. I have some 23.976 source that I want to cut in with it, so the best course of action for me would be to revert the speed back down to its original film speed and, of course, slow the audio as well; I can do this manually, but if there's a one-shot method that's great. I DO want to reduce the pitch with it, because the source is higher-pitched than it should be. One portion of this project may involve slowing 5.1 audio though, dunno if that's more difficult.

Also, I dunno if this requires using a pulldown in the file for rendering to DVD, but oftentimes Vegas doesn't display pulldown properly for editing, so if there's a way for me to get it all to 24p(?) and then put the pulldown flags on after editing, that'd be ideal. Or maybe I don't need the pulldown at all; I dunno. Not gonna be widely distributed, so wide compatibility isn't an issue. I'll also be rendering an AVCHD version, for whatever that's worth.

I'm wondering about the easiest way to do this. It's 1080p, so no resolution conversion necessary. So, in short, what I'm looking for is the slow-down method which doesn't remove or duplicate frames, but simply changes the speed and length of the video. I've never used AVISynth scripts, so if that's a part of it, I may need a simple explanation.

If this is sped up 1920x1080p25 material, pulldown isn't necessary. 1080p23.976 is native progressive and supported by AVCHD and blu-ray. But for SD DVD authoring, you need to add pulldown flags to bring up 23.976=>60i signal .

For the audio part you can use eac3to or besweet, and import the audio track separately

e.g. (assuming it's 5.1 ac3)
eac3to input.ac3 output.ac3 -slowdown

For the video portion, I would edit in a 1080p23.976 timeline . There will be no pulldown problems with vegas, because soft pulldown flags are only added after you edit and go to SD DVD. From that edited timeline, you can go to AVCHD/blu-ray or SD DVD within vegas

You might be able to change the header FPS and rewrap with tsmuxer, but sometimes it doesn't work, or vegas might have problems with it. Give it a try first

A sure fire way to do this is re-encode to a digital intermediate. I would use cineform, there is a free version now since gopro bought them out. This will make your editing experience very fluid. You can feed the avs script into vdub to encode to cineform for example. You need lots of HDD space

e.g.
DirectShowSource("video.m2ts")
AssumeFPS(24000,1001)

[rcavanah]

OK, fantastic...

By the way, deathray, got my hands on the source for this project (as you can see), and the PAL conversion seems to have been done improperly before; that seems to be why I had so much trouble with the VOB source. But, this way, I can get a 1080p version out of it, so it's all good.

As far as cineform, seems like a good idea because I have had some trouble with the source crashing vegas, even just editing in 25p mode (had to render out to MPEG2 HD and work from there). Do you have a basic idea of the size of a 2-hour 1080p cineform file with a moderate bitrate? I have decent HDD space to work with, but not tons.

EDIT: Ah, found it. Looks like 60gb to 80gb per hour, so totally doable. Thanks for the recommendation, didn't know there was a free version!

[poisondeathray]

I don't know if the free version has selectable quality levels, but the typical bitrate for an HD stream is around 120-240 Mb/s . Obviously it's higher for the higher quality levels like "filmscan2". So if your HD stream is a typical 20-30Mb/s , expect a ~5-10x increase in size

Filesize = bitrate x running time , so you can calculate more exact if you need to