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Audio bit rate in FCP / Quicktime

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Joe Violette
Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 3:12:07 pm

Hello all,

I have a quicktime movie file that needs to be 24 bit to play back correctly for a test screening.

When I pull the clip into FCP 7 and set the sequence settings to that clip, the audio bit rate shows to be 24.
However, when I open it in quicktime and look at it with the movie inspector window, it says that the clip is
Apple ProRes 422, 1920 x 1080 (1888 x 1062), Millions 16-bit Integer (Little Endian), Stereo, 48.000 kHz.

Could someone please tell me how this works? Am I missing something and/or why are they interpreted differently in FCP? Is there a way to be absolutely sure this clip has 24bit audio?

Thanks in advance for any help!


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Steve Eisen
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 3:23:36 pm

You want to make sure you have a ProRes 422 48kHz-24bit audio. Normal setting for audio is 48kHZ-16bit.

Steve Eisen
Eisen Video Productions
Vice President
Chicago Creative Pro Users Group


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Joe Violette
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 3:36:28 pm

Thank you Steve.

That is my issue though, it seems to be 16 bit according to quicktime, but the FCP 7 sequence I create by importing the clip when choosing to match sequence to clip settings set it to 24bit. Which has me confused - what do I actually have at the present moment ?

Also, since my sequence already sets itself to 24 bit, does this mean if I try to re-export I will wind up with 16 bit again for some reason?


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Ryan Holmes
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 3:48:09 pm

Things to double check:
(1) Original audio is in fact 24-bit
(2) Your sequence settings are set to 24-bit (not 16)
(3) Then make sure your export settings are correctly set or you can always force the export to be 24-bit audio when you export it

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost


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Nick Meyers
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 8:06:38 pm

[Joe Violette] " the FCP 7 sequence I create by importing the clip when choosing to match sequence to clip settings set it to 24bit."

so what does it say in the FCP browser, or in the clips' item properties?


nick


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Jean-Christophe Boulay
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 8:23:18 pm

Hi Joe,

The audio settings being set by FCP when conforming a timeline to the imported clip have a very tenuous relation the actual audio settings of the clip being imported. You can import 16-bit/44.1kHz all day and FCP will set that timeline to 24/48 every time for most codecs. Hence the recommended practice of having everything in the correct format before importing to FCP to edit, which is not your error, lucky you.

So you can't trust FCP on this. QT must be right. Trusting FCP for audio is rarely rewarded with success, in my experience. Once you have your final product imported to FCP, on a timeline set to its video settings and with the audio (incorrectly) set at 24/48, you just have to check your Audio Outputs tab is set allright, render that timeline to be sure, which should take next to no time at all, and export that to a self-contained movie. That should give you a movie with the same video parameters and with 24-bit audio.

As an aside, I very much doubt that the file "needs to be 24-bit to play back correctly". Any contemporary system that plays out digital files would have to have been set up in the most ham-fisted manner possible to not be bitrate-agile. But if I start telling people to not follow specs, night will turn to day and it'll rain frogs, so you follow those specs!

IHTH,

JC Boulay
Technical Director
Audio Z
Montreal, Canada
http://www.audioz.com


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Joe Violette
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 8:46:17 pm

Thanks JC,

What you said confirms my suspicions that Final Cut cannot be completely trusted. My situation was that I received the self-contained QT file and needed to make sure it met the specs for the test screening I mentioned, so I could not go into FCP and see the original edit/media.

I agree that play back should be fine with 16 bit, but when I enquired I was told it would be problematic, so I just wanted to "play it safe" and delivery the file exactly as requested.

Thank you (as well as thank you Nick who had similar questions)!


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Michael Aranyshev
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 10:32:49 pm

[Joe Violette] "What you said confirms my suspicions that Final Cut cannot be completely trusted. "

Did you check Item Properties for the clip in FCP? Did you scroll all the way to the right in the Browser to actually look what FCP says about your clip?


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Joe Violette
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 11:39:46 pm

Yep, and it was 16-bit, but I still don't understand why in my sequence settings would be 24 bit when I match them to a clip while importing....


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Jean-Christophe Boulay
Re: Audio bit rate in FCP / Quicktime
on Apr 3, 2013 at 2:15:44 pm

Just to specify, the Item Properties in FCP can absolutely be trusted for audio. I've never seen it wrong nor have I heard any stories about that.

JC Boulay
Technical Director
Audio Z
Montreal, Canada
http://www.audioz.com


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Nick Meyers
Re: Audio bit rate in FCP / Quicktime
on Apr 2, 2013 at 8:03:25 pm

where did the file come from?

sounds a bit like you may have exported it from FCP,
but i'm not sure

it's weird behaviour.
i just checked some files in QT Player7 that i knew were 24bit, and it shows them to be 24bit.
one was some location audio, the other was export from my timeline.

why not check in some other apps.

also, can i ask why it needs to be 24 bit to play back correctly?
is it some physical thing with the playback device, or just a quality issue


nick


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