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Preparing 30fps media for NTSC broadcast

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Keiichi MatsudaPreparing 30fps media for NTSC broadcast
by on Feb 17, 2011 at 5:32:35 pm

I've had a reasonably thorough search on this, and can't find anything definitive.

My music video is at 30fps, with the audio sync'd nicely. I want to prepare it for NTSC broadcast (29.97002something fps) and DVD distribution (I heard this should be 29.97 too) in the proper way if there is such a thing.

Instead of messing around with pulldowns/ups, frame blending etc that I dont understand well, I thought it may be ok to simply interpret the 30fps as 29.97fps, put it in its own 29.97fps comp, and add the audio track. As the video is now about 10 frames longer, I thought it might be possible to apply a time stretch to the audio, to sync it back to the video, and noone would be any the wiser.

This is basically just stretching the video and audio, easy as pie no?
Planning to output as 720p x264.

I'm currently having (probably) unrelated issues with AE not being able to read the 30fps file, so I cant test it, but is this method sound in principle?

Your answers may include:
- Yes, you are normal and your parents love you.
- Yes, it would work, but why not do it in QTpro/media encoder/squeeze, its fast and easy like this... (xyz)
- No, amateurs like you shouldn't be allowed to broadcast!
- Yes/No, but just give it to them/burn DVD at 30fps, noone cares about that rubbish any more.

Excuse my ignorance, I am blessed with my good ol' PAL and unfussy web video normally.

K


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Dave LaRondeRe: Preparing 30fps media for NTSC broadcast
by on Feb 17, 2011 at 5:39:29 pm

AE may not be a good first choice for this; you might be able to do it easier, faster and more accurately in a different application or applications.

What other software do you run -- editing, audio, etc?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Keiichi MatsudaRe: Preparing 30fps media for NTSC broadcast
by on Feb 17, 2011 at 5:54:36 pm

Im on a fast mac, but using Premiere over FCP as I like the Dynamic Link feature. Sound was supplied to me as an .aiff by the artist.

I dont have much experience with mastering DVDs, but I guess I'll jump into Encore after I've FTP'd the broadcast file.

My normal workflow is to render out of AE as a full HD monster (animation codec), then use Quicktime Pro to compress it into h264 and lower the resolution if necessary. My flatmate has Squeeze, but I've never used it before.

I was hoping there would be a simple way to gently pull on the ends of the 30p clip, letting the frames fall neatly into their new homes. The whole thing would be very slightly slower, but they've been nice clients so far.
I'd really like to avoid all that pull up/down malarky and frame blending if at all possible, as what I'm trying to do seems like it must have been done before.


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Dave LaRondeRe: Preparing 30fps media for NTSC broadcast
by on Feb 17, 2011 at 6:10:01 pm

I bet the original edit is still in Premiere then.

I use Final Cut Suite applications, and based this knowledge of an entirely different set of applications(!), perhaps the following might be possible:
  • Export the video and accompanying audio in QT's PNG codec (lossless, smaller file sizes than Animation) with an audio track, then reimport the file into Premiere.
  • Conform the frame rate to 29.97 in Premiere; export the audio track ONLY.
  • Using Soundbooth (Audition?), change the audio file's sample rate back to the original rate; it may have changed a bit during conforming.
  • Use the conformed video and repaired audio file to create the files necessary for distribution and DVD authoring.

The reason I recommend this: AE has a difficult time time-stretching audio accurately, which is important in lip-synced video.

I hope somebody with greater knowledge than mine about Premiere reads this, and slaps my hand if I've given out bad advice.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Keiichi MatsudaRe: Preparing 30fps media for NTSC broadcast
by on Feb 17, 2011 at 7:07:39 pm

Great!

I didnt realise that 'conforming' just changes the length of a frame, so that is exactly what I was talking about before but in grown-up language right? Also, how can I find the 'original sample rate' of my audio?

I'll give it a go as you suggested. unless a hand-slapper emerges soon.

Incidentally, can one conform, or export video with a different frame rate to the source in QTpro? Export options looks like you can, but no joy as yet.

Thanks for your kind help


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Dave LaRondeRe: Preparing 30fps media for NTSC broadcast
by on Feb 17, 2011 at 10:39:26 pm

I;m pretty sure changing the frame rate, then exporting via QT pro changes the frame rate ONLY. I don't think the duration of the clip changes.

For your situation, that sounds pretty good... until you realize there's very likely to be a little hiccup in the motion a couple-few times because of the slight frame rate mismatch.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Keiichi MatsudaRe: Preparing 30fps media for NTSC broadcast
by on Feb 17, 2011 at 11:41:40 pm

I was in a bit of a rush, so I had a go at the initial method I mentioned:

-interpret original 30fps footage as 29.97fps in AE
-put it in a comp (29.97fps)
-add the audio, and time stretch it by 100.1001%

You mentioned that AE doesnt do a good job of stretching audio, but it sounds fine on my fairly decent studio headphones. This may not be the super-pro route, but I was quite happy with the result, and Im not dropping frames as far as I know.

Thanks for the tips though, Ill bear this in mind. Strange theres not more info out there, as it seems to be a fairly common process.

K


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Dave LaRondeRe: Preparing 30fps media for NTSC broadcast
by on Feb 18, 2011 at 3:36:57 pm

Well, I'm glad it worked for you. It sounds like it was a lot easier than what I had proposed, that's for certain.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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