24p to PAL workflow

Spot|DSE wrote on 12/31/2005, 1:26 AM

Pray.
Seriously, getting good 24p footage to convert to PAL if it was shot in 720 x 480, is tough, especially for someone who has the work output quality as you do. It's not the framerate that will create havoc, it's the resize of the horizontal rez.
Open a PAL project, and drop your 24p footage into it. Pan/Crop to aspect ratio using a script. Edit. Output as PAL to a PAL deck, and that's the best you can do.
For giggles, I just tested this in Vegas 6 using some 24p footage (24pA) and it's not awesome, just acceptable. I'm viewing it on a laptop, full frame size, but it's also interlaced once it becomes 50i, and I can only look at it on a computer display, so maybe it's not as bad as I think.

Wolfgang S. wrote on 12/31/2005, 2:26 AM

I have done a small test too, simply by changing the render format:

PAL-DV-avi 25 fps, interlaced --> NTSC DV avi 24p --> PAL-DV-avi 25 fps, interlaced

What I have seen is that you loose a significant amount in sharpness, during that conversion. So, that is in line with your finding that the resizing will be the beast there. Maybe it is a good idea to add an additional step, where you apply a sharpness filter.

Douglas, why do you recommend to use pan/crop here? You always have to resize from 720x480 to 720x576 - is pan/crop better here then the way described above?

Spot|DSE wrote on 12/31/2005, 2:29 AM

I tried it both ways, and it appeared slightly sharper on my laptop using pan/crop than the straight drop-in and render. I didn't add sharpness or unsharp filter, which would help a little, I'm sure. I wasn't looking for a recipe, just wanted to see how better (if at all) Vegas 6 does the resample than Vegas 5 does. It does manage it better, btw. IMO, anyway.

Wolfgang S. wrote on 12/31/2005, 2:37 AM

Well, I have done my tests with Vegas6c - and did not compare it with Vegas5 at all.

The question is: why is pan/crop better then the direct conversion? In terms of the video signal flow - pan/crop takes place later then the media interpretation. Maybe that makes a difference.

tomadonna wrote on 12/31/2005, 6:39 AM

I have done this many times before:
Render the 24p project to an avi file, and then use a program such as Canopus Procoder to convert to PAL - works great...

Patryk Rebisz wrote on 12/31/2005, 8:42 AM

thanks for your responses. too bad i can't check the results on my external monitor... still thanks for sugestions.

Patryk Rebisz wrote on 12/31/2005, 3:55 PM

just a folow up question.... If i use Vegas' PAL preset and go with 1.2 pixal aspec and off for interlacing... Will the quality still suffer? I mean why is it that people shooting film have it easy when transferring to PAL?

farss wrote on 12/31/2005, 5:12 PM

Because they simply run the film at 25fps and scan it at PAL resolution, that's why film is still a very popular acquistion medium in TV production.
Bob.

Patryk Rebisz wrote on 12/31/2005, 5:16 PM

what about Hollywod productions? I guess the frame isn't a real issue here as the loss of resolution when upresing... right?

farss wrote on 12/31/2005, 5:41 PM

That's right,
in PAL land film is telecined at 25fps. Not done much these days, not too many stations have telecines themselves, thank goodness too, they used to grade the print on the fly and sometimes, particularly around this time of year, the results were spectacular spectacles of biblical propotions.
Today the master tapes for broadcast will be from 25fps transfers.
I think the Hollywood DVDs are done the same way, I think the results of a film scan is discrete frames at very high res and digitally it's easy enough to convert to either 24p or 25p with a 4% speedup.

I do recall some of the DVX100 crowd in the USA buying the PAL version of the camera just to get the extra resolution and suffering the 4% slowdown for film out or NTSC video out. 25p PAL would seem to convert very nicely to 24p NTSC and then apply pulldown to give good 60i. Going from 25p to 50i is a no brainer, still looks filmic, so with that workflow you have PAL and NTSC distribution covered.
There's two caveats to that though.
Shooting 25p in a 60Hz country can lead to flicker problems with some types of lighting.
If you ever need to shoot 60i with the camera, you're screwed.
Bob.