Does the DVD Specification Support 30p?

[Michael Sacci]

Dude how many time have I said yes it does.

[Michael Spooner]

Whoop, sorry. Didn’t realize you were the same guy. I’m just getting mixed messages from people around the net so I think I’m going to stick with 24p.

[Eric Pautsch]

Never heard of 29.97 progressive on DVD. Its either 29.97 interlaced or 23.98p with pulldown flags. Not sure how you are encoding but its definitely not a 30p MPEG2 stream.

EDIT: Correction! So its still an interlaced picture, but there is no time difference between fields?

[Michael Sacci]

[eric pautsch] “Not sure how you are encoding but its definitely not a 30p MPEG2 stream. “
Both Bitvice and Compressor will handle 30p source, maybe it is adding interlace flags.

The problem when deiinterlacing true interlaced footage is the some information is thrown away, you cannot simply display two fields as a single frame. So there maybe flags in the encode similar to 24p (minus pulldown). That way the progressive player knows to use all the info of the frame and not do some type of averaging or line doubling.

All this being said 30p is not something that is normal used, but the like is smoother than a 24p but still keeps the most filmic quality of progressive.

[eric pautsch] “EDIT: Correction! So its still an interlaced picture, but there is no time difference between fields? “
Well I would say that it CAN be, just like the 24p can be, it is just a simpler process, since there no pull down.

My head is now hurting. I know what your saying, I know what the spec are saying, I know what a progressive play should do, so I put it as a your are correct but…

[Enrique Orozco]

…again…. I’ve made many DVDs encoding my progressive HD source files as progressive mpeg2 and DVDarchitect doesn’t reencode the files…. the DVDs are 100% fully compatible with any player, looks great and if you “check” the VOB file-properties appears as 720 x 480 29.97 progressive files !!!!

good luck

Enrique Orozco R.
iDEA DigitalVideoStudio

[Eric Pautsch]

The only problem Enrique is that the spec only supports 29.97 interlaced and 23.98 with PD flags – the spec is very clear on this. So there’s a missing piece of the puzzle here.

My guess is that the “30p” is actually interlaced just that each frame has NO temporal differences. A “faux” 30p if you will. I’ll have to post this on the Tully List to see what the rest of the DVD world thinks.

I’ve never worked with 30p material before myself – find all this very confusing 🙂

[Michael Spooner]

I’m under the impression that 24p on DVD is also “faux” progressive, but for all intents and purposes it looks and behaves exactly like a progressive image should. The same is true when I tried encoding 30p on dvd. The image is most definitely progressive (no interlace lines or artifacts), and it’s running at 30fps. The motion of 60i with the picture quality of 24p.

I think I noticed a bit of flicker when I played it back on an interlaced TV. I think I read elsewhere that trying to interlace is where 30p has problems on some players/TVs.

[Eric Pautsch]

Here’s good thread to read:

https://forums.creativecow.net/thread/8/1040702#1040702

The thing to remember is DVD is 20 yr old technology. Progressive video was not a thought in the late eighties. A DVD compliant NTSC MPEG-2 video file must be stamped with a frame rate of 29.97 fps. There is only place for one frame rate code in the MPEG-2 headers, so you cannot stamp it with two different rates. This is regardless whether the original movie comes from film or not. There is no doubt about that. It is just a matter of fact.

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[Michael Sacci]

how about this for an answer, from https://www.dvddemystified.com/dvdfaq.html#1.40

There’s enormous confusion about whether DVD video is progressive or interlaced. Here’s the one true answer: Progressive-source video (such as from film) is usually encoded on DVD as interlaced field pairs that can be reinterleaved by a progressive player to recreate the original progressive video.

This is different from being interlaced footage being de-interlaced.

[Eric Pautsch]

Bingo! There’s the answer.

So to make it clear:

1. DVD is an interlaced format only
2. All MPEG 2 streams are stamped 29.97; 23.98 with PD flags=29.97
3. Progressive-source video (such as from film) is usually encoded on DVD as interlaced field pairs that can be reinterleaved by a progressive player to recreate the original progressive video.

This is different from being interlaced footage being de-interlaced.

So the 30p is actually encoded 29.97 interlaced field matching pairs

Do we agree on this? 🙂 I would love to put this away for good. lol