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Audio Frame rates?


Joe Riggs

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I'm trying to get a better understanding of how audio and frames rates work together, take an H4N for example, I could record video at 23.976 or 29.9, and the audio file from the H4N would match to either one of those. I don't have to set a frame rate for that (I'm not concerned with jam syncing time code or anything). 

However, what happens if your film is shot and edited at 23.976 but your sound designer does all his work in 29.97? Will there be a four frame sync difference when you get the audio file back? I'm not familiar with most DAWs, do you need to set a frame rate there before you begin work?

Edited by Joe Riggs
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didn't we just have this conversation last week with someone?

23.976 and 29.97 are the same speed relative to 24, just counted difrently

H4n is a non-sync recorder (no TC capabilities, (and not very quite))

depends on how stupid your DAW is

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Think of a second as a pizza. You can cut the pizza into 24 pieces, or 25, or 30. It is still the same amount of pizza, just cut into more or less pieces.

So - a second is a second is a second..... except......when the clock is ticking slightly slower. This was necessary way back when B&W TV became colour. They had to run the clocks slightly slower than the regular clocks, so that they could fit the colour information into the video. There are still 30 full frames, but because they are recorded and played back slightly slower, only 29.97 of them get shown in an actual real second.

So - a second of NTSC colour video lasts slightly longer than a real second. The pizza analagy still holds though - you can cut it into 24 or 30 pieces, they are just NTSC pieces.

 

Hope this helps.

 

Simon B

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Mmm the pizza analogy is delicious.

Ok, here's the deal, the project was shot and will be finished at 23.976, the so called "sound designer", an amateur, can only work in 29.97 (yes, I know, hire someone else, a professional, I would if it was up to me and the person hired wasn't related to the boss), so will there be drift in a 15 minute project when I get a mixdown WAV file back? Or any other ideas on how to keep sync?

Edited by Joe Riggs
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the project was shot and will be finished at 23.976, the so called "sound designer", an amateur, can only work in 29.97... so will there be drift in a 15 minute project when I get a mixdown WAV file back? 

1. If the sound designer is using any kind of modern audio software, it's sample-based and computes code on the fly. So no errors there: once things are in sync, they should stay in sync. (If they're working in a video program, it's probably frame based and all bets are off.)

2. Sound designer is presumably working to a reference .mov or .mp4, that has both picture and lipsync sound. If nobody's messed with sample rates (as opposed to frame rates), and their mix matches the ref, then they're in sync. (If the reference has sync errors, that's editorial's problem, not sound's... though the production will often ask sound to fix it.)

3. It sounds like this project has some aspects of mickey-mousedness. There are known workflow gotcha's, such as changing the code format in a popular NLE forced it to pull-down any audio imports, destroying what was good sync. Those are also editorial problems, though they might try to blame it on sound. 

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There's no editorial problems. The reference movie is  23.976 and everything is in sync, the only mickey-mousedness is the "sound designer" doesn't have professional  software (pro tools or a equivalent DAW that typically is used for film work). Therefore, when that reference movie is brought into whatever program this person uses it is on a 29.97 timeline, they will do all their work on that timeline, and export the audio from there.

I guess we will eventually find out if there's audio drift or not.  

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What is "ProTools or Equivalent"? Nuendo? Sadie? Fairlight?

Is it a brand name? (I've seen folks using the barest minimum of PT -- the kind bundled with basic interfaces, one step above the old "PTFree" -- calling themselves fully professional.)

Is price the factor? Does Reaper count? Does it count if you've added AATranslator? Are you more professional with any DAW if you've added a fully tricked-out SoundMiner?

Does it have to be current? Is a fullblown PT rig, of vintage and running in a PPC Mac, count? How about Orban Audicy with sync option? New England Digital's big rack full of cards?

I believe it's a fool's game to call someone professional or not, just based on what gear they use. 

--- Decades ago, when Society of Professional Audio Recording Studios was starting up, they decided my 4-suite 15-person operation wasn't professional: even though we were doing about half the national radio spots coming out of New England, and shipping an average of 500 dubs per week, we didn't have a 24-track.

--- And if you play that game today, then all those Subway Tuna producers on Craigslist must be fully pro if they're shooting on a Red!

So back to this thread: what makes this particular designer unprofessional, other than being related to the boss?

And while we're at it... what software limits you to 29.97? I can't think of any.

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Don;t know which software it is, but it is clearly nothing the caliber of Pro Tools or Nuendo. They can't accept OMFs or AAFs for goodness sake, I've also had the pleasure of listening to their work, I can confidently say we are dealing with an amateur, hobbyist maybe  but not a pro. 

 

 

 

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