Perhaps some clarification re: 23.98/24 and audio

[John Fishback]

The audio shop may not have known the difference between 23.976 and 24. Pro Tools has a simple dropdown to apply .1% up or down to deal with this. Changing the sample rate as Bouke suggests is the easiest way. BTW 16 vs 24 bit depth will not affect sync.

John

MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.8 QT7.6.4 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
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Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN

[Michael Nichols]

I have been 23.98 throughout. Even though the scans are at 24fps, I am working in a 23.98 sequence (with gluetools telling FCP that the scans are 23.98 clips). He must have been working in protools at 24 and not 23.98. Still can’t figure out why the speed change needs to be 100.10 percent and not 100.01 though.

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[Keith Pratt]

Put this into a scientific calculator: 23.976×100.1%.

Looking at the answer it gives you, why would the speed-up ever be 100.01%?

[Bouke Vahl]

You’re totally right.
What i’ve tried to say that a speedchange of 0.1 %, not 1 %
100.1 is indeed 0.1 percent more than 100…

My bad, sorry.

Bouke

https://www.videotoolshed.com/
smart tools for video pros

[Michael Nichols]

[Bouke Vahl] “You’re totally right.
What i’ve tried to say that a speedchange of 0.1 %, not 1 %
100.1 is indeed 0.1 percent more than 100…

My bad, sorry.

Bouke

https://www.videotoolshed.com/
smart tools for video pros “

I guess my problem is here is simply the math!! Forgive me, but if I am understanding this correctly, then I should be doing things right: When I apply the speed change in final cut pro, I have to set it to 100.10 percent, not 100.01 percent to re-sync the AIF file. 100.1 works and that is the correct speed change.

Abel Cine Tech – Rental Coordinator
We now have Red and SI-2K in our Rental Fleet!
212.462.0163 • mnichols [at] abelcine [dot] com

[Bouke Vahl]

To clarify, my original math was wrong, 100.1 is the correct number.
(as that is indeed a .1 % speed change)

But, in all cases:
If it works, don’t fix it…
I don’t know how your speedchange works, but as rule of thumb:
Speedchanges that involve sample rate correction use a pitch shift.
In your case, you want that.

To find out what kind of speedchange is used, watch the render time.
A speed change with SR conversion should be instant, while a speed change that tries to keep things intact takes time.

If in doubt, use an external util that gives you control over what you are doing.

hth,

Bouke

https://www.videotoolshed.com/
smart tools for video pros