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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

23.976 project time base and off speed lip sync

Morning Glory

Morning Glory

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I'm in prep for a feature film with extensive playback requiring lip sync (a musical!). The project time base is 23.98fps. Some playback they want at double time, transfered at ‘double speed’ 47.96 fps, and pitch
corrected, others they want to do at 'half time', 11.99 fps. Now, if my project time base is 23.98fps, when I set it to 48fps in camera, is it 48fps or 47.96fps? Likewise with 12fps. If it is truly 48fps ina 23.98fps project, the 47.96fps audio playback material will drift. I want to ensure that playback when sped up and camera when sped up will all sync up hunky dory and be no pain in the ass for post. Any thoughts on how I should proceed?
 
garth hagey said:
Now, if my project time base is 23.98fps, when I set it to 48fps in camera, is it 48fps or 47.96fps? Likewise with 12fps
Click to expand...

When shooting in Varispeed mode, my guess is that it's actually shooting 48fps and 12fps respectively. But I think someone from Red would need to verify this.

garth hagey said:
I want to ensure that playback when sped up and camera when sped up will all sync up hunky dory and be no pain in the ass for post. Any thoughts on how I should proceed?
Click to expand...

This is not a normal situation, so all I can say is TEST, TEST, TEST. That is the only way to ensure that it won't be a pain in the ass for post. You're shooting at various frame rates and trying to sync sound from an external recorder (at least I assume, because the camera does not capture audio in varispeed mode) so start out with some basic tests, but keep in mind that you'll eventually want to test out a decent length clip to ensure you aren't getting any drift.
 
It is a good question...

One solution (assuming varispeed modes are bang on the money in terms of fps, whih I think you'll find they are) would be to shoot at true 24p, which will then allow precise matching of double and half speed shots. Obviously you'll need to have the post boys happy to convert it into 23.976 (and if you're doing work this fine please remember that 23.98 is shorthand - the correct rate is 23.976fps) if that's your deliverable.

We're in PAL land here and so thankfully don't have to deal with those horrible fractional rates very often, but I would presume the same trick should work that we use to move from 24fps -> 25fps and vice-versa - simply run the film at the new timing without changing a thing visually and compensate the audio pitch to match (it's around 4% for the 24fps to 25fps conversion, but would be tiny (and perhaps even unnecessary) for 24fps -> 23.976fps) - or is there some reason that won't work?
 
Varispeed Frame Rate

Varispeed Frame Rate

The project time base is 23.98fps. Some playback they want at double time, transfered at ‘double speed’ 47.96 fps, and pitch corrected, others they want to do at 'half time', 11.99 fps.

Now, if my project time base is 23.98fps, when I set it to 48fps in camera, is it 48fps or 47.96fps?
Click to expand...

The answer is - we just round the FPS displayed in the GUI to whole numbers.

So if you are working with a 23.98 Project TIME BASE, then "48 fps" is 47.96 etc ..
 
Stuart English said:
The answer is - we just round the FPS displayed in the GUI to whole numbers.

So if you are working with a 23.98 Project TIME BASE, then "48 fps" is 47.96 etc ..
Click to expand...

Good to know. So is it safe to assume that with a 24 Project TIME BASE "48fps" is 48.00?
 
Much Gratitude

Much Gratitude

Thank you for your answer, Stuart. Just the information I was looking for. Much Obliged!
 
Wouldn't it really by 47.952? Aren't the whole numbers a - .1% from the whole number?

Michael
 
Not trying to ressurect a thread here, but I was speaking to a sound friend of mine (I'm an AC) and we were trying to get to the bottom of this.

I understand that when in a drop-frame system, the VARISPEED settings will abide (record @ 47.952 instead of true 48). Will this apply for other frame-rates? For instance, would it record at a true 50fps when set at "50" or would it be some drop-frame equivalent? Any help is great. Thanks!
 
Brendan_H_Banks said:
Not trying to ressurect a thread here, but I was speaking to a sound friend of mine (I'm an AC) and we were trying to get to the bottom of this.

I understand that when in a drop-frame system, the VARISPEED settings will abide (record @ 47.952 instead of true 48). Will this apply for other frame-rates? For instance, would it record at a true 50fps when set at "50" or would it be some drop-frame equivalent? Any help is great. Thanks!
Click to expand...

These are completely different things. Drop-frame time code has no bearing on recording frame rates, it is simply a way to reconcile the fact that 1800 video frames add up to more than a minute. Drop-frame TC reconciles TC with real time. (especially useful to broadcasters who have to fit a show into a fixed slot in real time.)
 
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