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Nomad TC set to 23.97, C300 set to 24p- Dumbslate, Sync drifting :(


Mike Wally

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Hey guys,

So, I'm on day 14/15 on this Indy feature that we've been shooting on the Canon C300. Apparently, there was a miss-communication with me and the camera department on the first day, and this whole time we've been recording 24p video while I have been using 23.97 for my Nomad-6. Simple set up with a dumbslate, the editors assistant said that doing the typical ".1%" speed up is not doing the trick to fix the drifting of the sound sync. Editing is being done in FCP.

Has anyone figured out tips or tricks for working with this? Plug ins, programs, ect?

Thank you very much,

-W

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You can use WaveAgent to stamp the TC frame rate as 24 but the timecode start values will still not match between audio and video. Audio and video will no longer drift in FCP though. I have seen FCP 7 time compress/expand audio based on the frame rate stamp. For instance, if the sequence is 24 FPS and the audio files are stamped 23.976, FCP will actually force the audio to playback a little bit faster. If FCP is doing this, re-stamping the TC FR will eliminate the drift caused by the increased playback speed. Manual sync will be required because as I mentioned, any start TC stamps will basically be useless. 23.976 to 24 conversion is not a "compatible" conversion in the world of start TC stamps.

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Al, I think anybody who shoots in 24.00 on this little camera is crazy, at least with most post workflows with which I'm familiar. The camera can absolutely, 100% do 23.98:

CanonC300specs.jpg

I would question their entire process from the git-go. This is another one of those cases where they have to check the workflow before the start of production. I'm stunned that this wasn't discovered until day 14.

If it's a 23.98 vs. 24.00 TC issue, I believe this will be a 3 frame per minute pull-up, which is not awful (but not ideal, either). All of this can be fixed -- at the worst, they can try a .1% speed-up outside of the editing program and see what happens. Note that a lot depends on the specific import settings (assuming Final Cut Pro).

The only legitimate reason I can think of to go with 24.00fps is for people who are positively going to go through a film-out delivery. Even then, 23.98 is a better post workflow, and the film recording people can always speed up picture and sound to 24.00 for the final. The key is for code and framerates to be at the same integer rate -- 23.98 for both (or 29.97 for sound), or 24.00 for both (or (30.00 for sound). That works fine. If one is at a fractional rate but not the other, chaos will ensue.

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I think one major problem is the use of the term 24p. Wasn't 24p actually 23.98 on some cameras? Maybe I'm just confused. Oh the madness.

Yeah, sometimes a DP, who isn't overly technical will say it's 24, when in fact it's 23.98. I always get a clarification, and am often ridiculed for it, since so few "video" cameras can do true 24fps shooting.

I will from now on pull up this thread when someone gives me attitude about me being a nerd, or thinks I'm needlessly breaking their stones.

So, why are they doing that anyway? I'm curious.

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" I would question their entire process from the git-go. This is another one of those cases where they have to check the workflow before the start of production. I'm stunned that this wasn't discovered until day 14. "

who made the decisions? and was it in writing?

these don't ever go out of style: workflow test

they probably are that far behind starting post..??

" we've been recording 24p video while I have been using 23.97 for my Nomad-6. "

since it seems to be between camera and sound, why did they use different settings (from each other) without verifying?

" anybody who shoots in 24.00 on this little camera is crazy, "

well, that way it will be just like film... :blink:

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So lies the communication problem, even among sound mixers.

Two different terms here.

FPS

Framerate.

23.976FPS is 24FPS

WHY?

Ask an editor who is working on a project using 23.9 TC to give you one second of footage.

They will give you 24 frames. NOBODY! cuts on a fraction of a frame.

Framerate is the difference.

The chart Al Mcguire looks correct, identifying settings as Framerate.

So when you ask how many FPS are you shooting, and the answer is 24FPS or 24p... that is not enough info.

Verify the Framerate..

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It isn't always a bad idea to shoot true 24 fps using digital video in certain situations. If a production requires both film and digital video cameras, frame rate conversion can be avoided by shooting true 24 fps when using the digital camera. Because of instances like this, it's extremely important to make absolutely sure that your timecode generator is set to the correct TC frame rate.

With the growing popularity in the video world for true 24 fps, coupled with cameras that support true 24fps, it's always best to input the camera's timecode signal into the recorder (with TC I/O) or dedicated TC generator to verify the TC FR settings of that camera. This simple step will eliminate this misunderstanding/confusion on set and minimize TC problems in post.

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It isn't always a bad idea to shoot true 24 fps using digital video in certain situations. If a production requires both film and digital video cameras, frame rate conversion can be avoided by shooting true 24 fps when using the digital camera.

Actually... the Panavision Panaflexes (all recent versions) and most of the Arri 35 film cameras can shoot 23.98fps with film. We have used these in post when we needed to go back and forth between film and videotape within the same scene with the exact same sound timecode... but that was back in the 1990s. I can recall several music videos that did this (as one example).

If the show has been shooting 24.00fps film all along, they should stick with that. I honestly do not see a point in shooting 24.00fps digital anymore, but that's just my opinion as a post guy. I think this is one of those things that should be discussed with a post supervisor on the phone, make sure they get an "are you sure you want to do this?" in conversation, and then ask for an email conversation just as a CYA mode.

I've been doing HD projects since 1999, and so far, the only 24.00fps project I've ever dealt with was Adam Sandler's Grownups back in 2010, which was a huge hit that made $268M. It can work, but we had much confusion and consternation for the first day or two; after that, it was flawless in every way in terms of post. (Note that dailies and the offline edit were all done at 23.98, and we pulled the picture and sound down .1% during playback, just as you would with film. I have no idea how they conformed it all in the end.)

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Actually... the Panavision Panaflexes (all recent versions) and most of the Arri 35 film cameras can shoot 23.98fps with film. end.)

Very true. I suppose I am just trying to provide a reasonable example as to why one would choose to use true 24fps when using digital video. I think many times the decision to use true 24 fps is made with no real reason behind it, aside from, "we want that film look." My key point was that there are many different ways to tackle a production. Not to say that a better and probably more efficient workflow isn't available but when "24" is mentioned, it's best to verify what is actually meant. Just like the other recent post about the "59.94 DF timecode" requirement. People say things and actually mean something completely different... or just don't fully understand what they are asking for.

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Ok...well the issue was pretty much resolved-

But I just got an email from the editor assistant saying this:

Also, I'm having a strange issue with a couple of clips recorded right before 148E take 1: The audio for the takes 148C takes 1-4 and 148D takes 1-2 plays back very fast, with a "chipmunk" effect, and so the audio drifts out of sync right from the start.

I tried manually adjusting the audio speed for those takes in the timeline. When I slowed them down to 91.85% it roughly looks in sync - but that's just by eye, based on trial and error.

Do you have any idea why those clips don't play at normal speed or if there is an exact adjustment that can be made to get them to play at normal speed?

(I did make sure that those clips were adjusted to 24 fps via Wave Agent, just like all other clips which were originally at 23.976. However, that didn't seem to make a difference.)

I checked my primary recorded files, and found they do seem to sound a bit sped up. I have no idea why though.

I also mentioned this is a low/no budget feature, right? They will run into problems that need to be fixed in post because they didnt spend the time in production or tried to cut corners to save money...which they will end up spending twice as much in post.

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" the only 24.00fps project I've ever dealt with was Adam Sandler's Grownups back in 2010, which was a huge hit that made $268M. "

thus, everyone wants to shoot at 24.000

" I checked my primary recorded files, and found they do seem to sound a bit sped up. "

first step in troubleshooting...

now you need to work on "why"

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