Reading the online help it would seem that both frame rates add pulldown. The 23.97 + 2-3 Pulldown uses 2-3-3-2 pulldown also know as 24pA (Advanced). According to the manual this allows for more efficient pulldown removal. As far as I know it also creates more judder compared to the traditional pulldown. Google will find you heaps of info on this. In terms of compatibilty it would make no difference. It would make a difference in terms of how motion appears. 24pA seems not recommended for viewing, only editing, as it allows complete recovery of the original frames.

Bob.

24pA seems not recommended for viewing, only editing, as it allows complete recovery of the original frames.

Bob, if 24pA (aka 23.97 + 2-3 Pulldown, if I understand correctly) is recommended for editing, not viewing - then why is it the default fps in the 24p, DVDA NTSC widescreen DVD template? Anything going to DVD is obviously intended for viewing, not editing...

I guess my decision making problem boils down to whether I should trust SCS this default fps is there intentionally or not. I mean, what would a person not aware of intricacies involved do, facing my dilemma? Well, I've got my project ready; it's 25p but what the heck - good old Vegas offers a ready template to transcode it into what I need at the moment, i.e. a 24p, NTSC DVD...

It's a pity we learned not to trust SCS blindly...

Reading the online help it would seem that both frame rates add pulldown

Bob, I followed you and studied the Vegas Help/manual; it seems the above statement is correct as the files, resulting from rendering using either fps, are of similar sizes.

But this only adds to my confusion! The only explanation that comes to my mind is that the NTSC DVD players/TV's expect all 59.97 fields anyway, and would either remove the pulldown or not, depending on the progressive flag presence. If this is the case, encoding with or without the 2-3 puldown added shouldn't make any difference.

HAving said that, I wouldn't like Vegas to create 60 fields out of my 25 frames !

Very, very few SD players and TVs can display 24p natively, only 60i which means by one means or another it will have pulldown of one form or another. So no, what kind of pulldown you use will affect what the viewer sees.

Bob.

OK, let me reword my question, and address it to our American friends on this forum:

Please forget for a moment that my project and source material are both 25p, and tell me which fps do you use when preparing video stream for your progressive NTSC DVD's: 23.97, or 23.97 + 2-3 pulldown (Vegas default for this format)?

No body's replied, so I'm trying to reply myself counting some knowledgeable NTSC person would chime in finally. In the Wikipedia, one can read:

DVDs, however, are capable of storing the native 24p frames. Every Hollywood movie is laid to disc as a 24p (actually 23.976p – see below) stream. With a progressive-scan DVD player and a progressive display, such as an HDTV, only the progressive frames are displayed and there is no conversion to an interlaced format – eliminating the appearance of any interlace or de-interlacing artifacts. When displayed on a standard NTSC TV (which only display 60i) the DVD player will add 3:2 pulldown to the signal.

This would mean that I'd be OK encoding to just 23.976 without the pulldown added. But 2 questions bite me:

- if so, why does Vegas DVDA 24p NTSC default template contain pulldown?

- also, why do my encodes with and w/o pulldown not differ in size (I'd expect the files with pulldown added to be larger)?

- if so, why does Vegas DVDA 24p NTSC default template contain pulldown?

Probably because this gives 'maximum compatibility' (just because something is in the spec it doesn't mean all players handle it as well as they should....)

- also, why do my encodes with and w/o pulldown not differ in size (I'd expect the files with pulldown added to be larger)?

The pulldown is done by adding flags to the stream which indicate to the MPEG decoder the fields to be repeated - that way no extra (redundant) video information needs to be added to the stream. This is the direct equivalent of how a telecine machine moves (pulls) the film past the image sensor, which is where the term 'pulldown' comes from.

(As an aside, the size of an MPEG file is determined by the duration and the target average bitrate - when using CBR or controlled VBR encoding - not by the video content).

Tony

Thanks for this answer, Tony.

I have just took one step further and it seems that - apart from the "maximum compatibility" reasons Tony mentioned - only the 23 + pulldown version can be swallowed by DVDA without recompression. DVDA doesn't provide NTSC DVD in 24p format (progressive as such is only available for BD). When set to 29.97 (the only option), it can encode a progressive 24p with pulldown added without recompressing it - which is what I want.

On another note: some time ago when I first encoded my PAL DVD we had a long discussion on the aspect ration change when rendering to the Vegas PAL widescreen DVD template from a 1080 timeline. The output seemed to be stretched horizontally (very slightly, but noticeably); at those time Robert W came up with the advice to change the horizontal and vertical HD frame sizes to avoid that.

I'm now preparing for lengthy rendering into NTSC; am I to expect similar aspect ratio problems, or (given that NTSC has always been the "more loved child" of SCS) will Vegas take care of it?

You want the truth, you can't handle the truth. Grazie read that and he's still in therapy. I warned you.

Bob.

I took a short look, and I'm afraid I'd be following Grazie if I wanted to figure it out :)

Not at the moment; I guess I prefer the old good trial and error method - at least from my HD to PAL conversion experience, I know which way to go when.