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Old December 1st, 2009, 07:56 PM   #1
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Please help - 30p DVD hell.

I am having some trouble putting a 30p project on DVD. Hopefully someone can help me.

As far as I know (and someone correct me if I am wrong), the average DVD player will take the 30p content on the disc and pass it along to the TV as a 60i stream. Then, the TV is supposed to recognize that the 60i stream originated as 30p, reconstruct the original frames from adjacent fields, and then play each frame twice to achieve its native 60p playback.

However, I have tested my 30p DVD on two different DVD players, and two different HDTVs, and the 60i stream coming from the DVD player is NOT being handled correctly. Instead of recreating the original progressive frames, the TV is performing its own 60i-to-60p conversion (i.e., using each field to create its own full frame), and this results in a flickering mess.

I have no idea where the problem lies. Do I need a special DVD player and/or TV to correctly play a 30p DVD? That would seem strange considering that all Hollywood DVDs are 24p and seem to work fine. I realize there are progressive scan DVD players, but it was my understanding that even normal DVD players should recognize and pass along a progressive flag to the TV, so that the TV can correctly reassemble the original frames.

Or is the problem in the DVD itself? I know for a fact the m2v files created by Compressor are indeed 30p. Could it be that DVDSP is not flagging the video as truly progressive? How can I be sure?

Please help!

Thanks,

Mike
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Old December 1st, 2009, 08:13 PM   #2
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To really dig deep into what's going wrong a great deal more info is required to fully understand your workflow and output.

- What was the original editing format in the FCP timeline?
- How did you export your finished sequence to Compressor?
- What settings did you use in Compressor to make your MPEG-2 compliant files?
- In Compressor did you force a frame-rate conversion to 30p from 29.97 (see screen-grab)? If so, this is not a DVD-spec compliant format and is the source of your screen-flickering.

Answer these questions and those of us that have time will chime in.
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Please help - 30p DVD hell.-screen-shot-2009-12-01-7.09.09-pm.png  
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Old December 1st, 2009, 08:51 PM   #3
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i will answer your questions, but i am pretty sure my workflow is not the problem.

Original footage is 29.97p, and FCP timeline is a 29.97p Prores422. And yes, I am sure that the "Interlaced" checkbox in the Prores settings was left unchecked.

Exported a quicktime reference file using "current settings"

Opened the reference file in Compressor, which correctly identified the video as 29.97p. Created a m2v DVD file (NTSC, 29.97, 4:3, progressive) with all frame controls OFF.

Imported into DVDSP, which analyzed the file and gave it the green light. It was never re-encoded.

In short, the file is definitely DVD-legal 29.97p.

Another forum suggested that when a DVD player passes along a progressive source at 60i, most HDTVs will ONLY recognize and correctly display a 24p source, and NOT a 30p source. The thought was that 24p sources will be recognized, deinterlaced, and played back in a 3:2 cadence to make the 60p, while 30p sources will not be recognized. This woudl explain what I am seeing, but is really true that most HDTVs can't deal wth 30p correctly?

Thanks for any and all help.

Mike
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Old December 1st, 2009, 08:56 PM   #4
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I'd think it's right that very few TV's will display 30p correctly. If it's not a known broadcast format, or something that is enforced/distributed by the big boys, then you are out of luck.

24P is known because the pull down is required to play feature films correctly. Nobody at all commercially distributes as 30P, except online.
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Old December 1st, 2009, 09:27 PM   #5
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Quote:
Originally Posted by Mike Dominic View Post
... but is really true that most HDTVs can't deal wth 30p correctly?

Thanks for any and all help.

Mike
No, that's absolutely not true. 29.97 AND 30p are both supported by 60hz (NTSC) HDTV systems. In fact ABC broadcasts it's HD content in 720 30p for most of it's material (with exception to sports), so if HDTV sets couldn't translate that signal then nobody would be watching ABC channels. See the Wiki page about broadcast HD formats:

High-definition television - Wikipedia, the free encyclopedia

This same information is also covered in the "HD and Broadcast Formats" PDF guide included in the built-in FCP users manual.

With regard to the SD encodes for DVD my guess is that something small has gone unnoticed in the workflow to cause a non-standard MPEG file. The DVD-spec allows for a broad range of formats that DVDSP will allow with "green" indicators but that doesn't mean it's optimized for progressive DVD players.

I'd try re-encoding very short test runs, no more than a 10 second clips using various Compressor settings and making sure there isn't anything in your DVDSP image with regard to flags/preferences that might cause a conflict in playback.

It's going to take some digging - and possibly a fresh set of eyes to physically look over your project to make sure everything's setup properly, but my gut tells me this is a simple fix.
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Old December 1st, 2009, 09:49 PM   #6
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According to everything I have ever heard/read, there are only three DVD-legal framerates for NTSC:

23.98p, 29.97p, and 29.97i (or 59.94i if you want to call it that). In fact, Compressor will not even allow the creation of anything else in its NTSC DVD template. The only other options in Compressor deal with data rate, GOP structure, etc., and I have already messed with those to see if I could get the video to play back correctly. Basically, all Compressor is doing in this case is taking a 29.97p 4:3 Prores quicktime file and changing it to a 29.97p 4:3 mpeg-2 file. It really is a very transparent encode and I don't know what I could possibly be missing.

What other specs are you suggesting are legal for NTSC DVD?
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Old December 1st, 2009, 09:55 PM   #7
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On the surface it sounds as if everything is being done properly but unless someone else sees something obvious I haven't then I'd suggest bringing in someone to physically look at everything from the FCP timeline to the DVDSP project setup. It's even possible the physical media itself is causing the problem - there are so many small things it *might* be, I still feel this should be a simple fix.
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Old December 1st, 2009, 09:56 PM   #8
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Well, after some more tests and some more forum browsing, i think i may have found someone with the answer. This is quoted from a user on a different forum:



"Of course 30p can be encoded as 60i, however interlace presentation has flicker issues if the source vertical bandwidth is too high. 30p to 60i can cause twittering (inter-line flicker) when a display converts 60i to 60p for HD display (most displays aren't expecting 30p over 60i sources, so they do the interpolation wrong.) ... Bascially most modern display can do 2-3 pulldown reconstruction, but not all do 2-2 (30p in 60i) pulldown detection, mainly because 2-2 sources are rare in professional sources.

DVD -- doesn't have either 24p or 30p profiles, only 60i, but all progressive DVD player can remove 2-3 pulldown, but not all 2-2, so same issues as BluRay. So 24p looks go on progressive displays, yet the 30p experience is varied. CRT display is fine for both, its the move to 60p progressive displays that is the issue.

Note: 24p on DVD/BluRay, pulldown is added automatically by the authoring sotware, you don't want to add pulldown manually with After Effects or elsewhere as the authoring software will like encode the image as regular 60i source (20% less efficient = lower quality) and not set the repeat flags -- many progressive DVD players use the repeat flags to extract pulldown. 30p on DVD has no repeat flags, making progressive detection more difficult."



It seems most HDTVs do not correctly detect a 30p source in a 60i stream, resulting in the flickering I was seeing.

Thanks to all for responding.

Last edited by Mike Dominic; December 2nd, 2009 at 01:48 AM.
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Old December 2nd, 2009, 04:14 AM   #9
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Quote:
Originally Posted by Robert Lane View Post
No, that's absolutely not true. 29.97 AND 30p are both supported by 60hz (NTSC) HDTV systems. In fact ABC broadcasts it's HD content in 720 30p for most of it's material (with exception to sports), so if HDTV sets couldn't translate that signal then nobody would be watching ABC channels. See the Wiki page about broadcast HD formats:
I should have been more specific in my response that I was referring to SD/DVD deliverables, not HD. And as the original poster has pointed it out many HDTV's aren't set up to handle this sort of conversion correctly because it was never a common SD deliverable format.
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Old December 2nd, 2009, 05:19 PM   #10
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I've been producing 30p DVD's for 5 years now. Never had a problem, ever. Even in third world countries. When I went to Indonesia I tried out my 30p demo reel on the cheapest, no brand name players and tv's. I was amazed at how good it looked even on old school CRT's.

No problems in India, Hong Kong, Indonesia, Australia, Hungary, UK, Peru, Mexico, Singapore, or of course the US.
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Old December 3rd, 2009, 06:57 PM   #11
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just because the footage is progressive and the encoding is 'progressive' (actually an interlaced stream but 'flagged' for progressive playback), doesn't mean the HDTV will get it right. Of all the formats it has to deal with, progressive 30P would be the least common I would imagine.

Justin, in your case you are not commenting on the same issue - case in point you mention the reel looking good on old school CRT's, this by their very nature will only be playing back your footage as interlaced - it won't be forcing true progressive output onto a display that can't handle it.
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