Pal 25p (on Panasonic AGDVX100) and Vegas + DVD Architect

PDB wrote on 7/7/2003, 6:21 AM
Hi everyone!

I was hoping to get some advice on this topic given that the SF Whitepaper on 24p has little info on 25p...

Anything special we should be aware of when working with 25p as regards settings etc? Any points worth considering if for some strange reason we need to mix 25p with 50i in the same project? Does a 25p DVD play on any setop box? any settings to ensure compatibility?

Many thanks in advance for any advice: can´t wait to put my first project onto dvd...:-)

All the best,

Paul.

Comments

AlexB wrote on 7/7/2003, 7:50 AM
Hi, Paul.
While the DVX100 is an interesting machine in PAL, too, there's nothing special about 25p. While 24p is a complicated format with some tricky pulldown to pack 24 full frames into a normal 60i DV stream, 25p rathe compares to 30p: just two fields of a progressive frame one after the other. So in Vegas, it's just another PAL DV setup with the field order set to none(progressive). Settops can play 25p DVDs and while I can't positively state that I mixed 25p and 50i on a DVD myself, I think it should work. By far the quickest way to test that: put your project on a RW disk and try!
Regards A.
mikkie wrote on 7/7/2003, 9:03 AM
In case it helps, *Might* want to do a bit of research on the web etc. regarding the flags set in mpg2 video, then play around with it yourself.

My understanding is that when frame rates are mixed on a DVD, the player reads the mpg2 flags and displays the video accordingly. In NTSC you would have a flag that forces 29.97 throughout the DVD, flags for interlaced or progressive frames, flags to add pulldown etc., the latter being the difference between the two 23.976 frame rates in the Mainconcept encoder in Vegas. RE: pulldown flags, a sequence instruction of sorts, tells the player which frames to display when to simulate fields. Because of these flags, 29.97i and 23.976p are often mixed seamlessly in/on NTSC DVDs, as with a 29.97i leader into a 23.976p film.

On the other hand, I've seen 23.976p video displayed by a set top box more accurately and smoothly, using internal routines/circuitry, then video with these flags set. Mpg2 from VV4c doesn't seem to have this limitation, plays at least as well, often beter - perhaps because of the extra box for field prediction selected in the custom dialog when pulldown is chosen?

Know PAL is a simpler routine, but alas don't have any info I'd consider concrete, rather a few contradictory statements I've come across. And there's not a huge amount of info on this stuff that I could find anywhere. If you're concerned about compatibility, definitely worth looking into I think.
RBartlett wrote on 7/7/2003, 11:14 AM
Some DVD players can play 25p PAL, namely the recent Tag McLaren range.
This range is for elitist home cinema for those who drive Aston Martin cars etc. Those who pay folk to press the remote for them or receive speech command!

25p PAL is limited for players that can drive a PAL progressive TV, another premium feature. Sure, you can watch 25p data encoded as 50i on an interlaced monitor but without truly being what you ask for PDB. Many TVs in PAL regions operate only in 29.97p on an NTSC frame size when they kick into progressive mode.

Best step is to serve the 24p features of worldwide equipment as NTSC format.
So reduce your frame(, or AR squish) to 720x480. Stretch your video so that it fits into a 24p project, 24 of the original 25 frames go into a given second, with the remainder passed into the next unit second etc etc. Then pitch convert +4% the audio (which you've already stretched in time).

It would be better if these cameras were multistandard.
I think 25p PAL DVD is a DVD-forum specified option. It is a minority one though.

There is much coverage of these foibles in the UK Home Cinema journal press.