Audio data rate

Hey guys-another problem coming from my end--you've been a great help so far, so well, I appreciate it...
So, here's the problem now...we're trying to cut in audio and half of it we have to render, the other half we do not. I've found out why-the data rate is different...now, how do I change that? I figure it is in iTunes, although all the files were converting using the program...
The ones we cannot use are at a data rate of 172.3 k/sec and the ones we can are at 187.5 k/sec.
Any thoughts?
Thanks-
Jeff

What happens if you open one of your audio clips up in QuickTime Pro and press Apple-I?

You should see 48 KHz sample rate AIFF and 16 bit stereo. If you see anything else, Final Cut may not cooperate with you over the length of the show. Even 44.1 KHz (CD Audio) sample rates can cause trouble.

I'm not sure where you got those numbers from, but you may be looking in the wrong place.

Koz

44.1 wont need a render, though.
what are these files?

MP3? AAC?

they'll need rendering,
and even then they'll sound bad.

convert to 48k, 16bit AIFF *BEFORE* you import the file to FCP.

you can use iTunes, or Compressor.
or quickly create your own custom AIFF converter Droplet using compressor.
read this:
[www.lafcpug.org]

cheers,
nick

Hey Nick, off the subject but.....


I want to thank you for pointing out a very simple but truly useful tool to me. That would be shift arrow to move the playback cursor by one second. I cut a lot of music and it is extremely useful.

Thanks again man.

dave

> 44.1 wont need a render, though.

It would if the timeline is set to 48kHz. Unless there an FCP5 upgrade I haven't been using.

Cross-check clip settings (APPLE-9) with Sequence Settings (APPLE-0). Everything must match or it's render time.

hey, thanks dave..
yeah, that's a bit left-field, but surely appreciated!

"> 44.1 wont need a render, though.
It would if the timeline is set to 48kHz."

huh?

we must be using different terminology i think, derek.
44.1 doesn't need to render on a 48k timeline.

you get a green line on the clip which indicates that it needs re-sampleing, or some sort of processing on the fly.

but i very rarely need to render straight audio, and i include 48 AND 44.1 in that.
(i've got a lot sound FX at 44.1)

by render, i mean the red-line, beep-beep-beep kind of render


nick

Technically any render line in the timeline means it needs to be rendered. You might get real-time playback, but it still needs to be rendered for output. Generally I think you're better off converting the files to the correct sample rate before using it. Or render at item level if you don't want to bother with that. That way you'll get more tracks playing back in RT before the dreaded beeping appears. Leaving the audio unrendered gives you lower track capability.



All the best,

Tom

yes that;s all true.
and in fact, i eventually i DO "render", when i do the audio mixdown

but in reality i never need to render "green Line" audio the way i would have to render "Green Line" video.
i cant hear the difference!
also i very rarely need to render to combat the red line or the beep-beep.
and if i do, i generally go into my user prefs and up the number of RT tracks.

i dont have a blisteringly fast system,
but i always at least double the number of RT audio tracks,
from 8 up to 16.
that;s MY preference default.
8 is ridiculously conservative,
and 16 might be, too.
i'll often bump it up to 20 or 24 if needed.

it may get a few people offside, but the whole "everything has to be 48" thing just isnt an issue with me.
i;ve been using 44.1 audio in 48 timelines since FCP2 without any noticeable issues.

in fact, when i did the 24fps project, ALL the audio had the green line,
as the sample rate changed as a result of conforming.
(we were syncing in telecine)

thinking about it, we DID have some weird audio glitches on that one, that even mixdowns didn't fix.
maybe that was FCP 4.11?
maybe that was my 800Hmz system?
maybe the FW drives?

oh, well, i still think that even on modest systems, mixed audio rates is basically a non-issue.
wrong formats, like MP3, and AAC, however...

cheers,
nick

I'm with Nick. I get a *red* line when I mix sample rates (probably because I'm using FCP4.5 at home) -- that's for certain because I just had this issue yesterday. But on the FCP5 systems I've used, the issue has never come up because I always convert to 48kHz. However, I've never had sync or real sound-quality issues from using 44.1kHz sound files in a 48kHz timeline, unless there's a formatting issue -- MP3s, etc.

My real-time mixing at home is four tracks! At work I go as high as eight tracks. I guess I'm so used to rendering that it's become a non-issue. Perform an operation, OPTION-R, APPLE-S. Left-hand twitch.

At any rate, I think what we're trying to say is:

1. Match all settings. It works better.
2. Render your sound anyway. You're gonna have to sooner or later.

no, i'm saying:

1. matching settings doesn't make much difference with audio,
so dont bust a gut converting from 44.1 to 48k, just to get it into FCP.
-if you DO have to convert from MP3, say, then you should conform to 48k 16bit standard
-if you use iTunes to get track names, then by all means set it to convert to 48k
-if you've got a bunch of 44.1 files that you want to use, just use 'em

2. if you need to render, up your RT track allocation.
-(within reason, and keep an eye out for performance. but as i said i would have been working FCP set to 16 tracks all the time when cutting a feature film on a 800Mhz powerbook)
-remember to do an audio mixdown before you export.

if you are going to render, you should try "item level"
i don't use it much, but i *think* that the items don't lose their renders as easily as video clips do.


"My real-time mixing at home is four tracks! At work I go as high as eight tracks"

wow, you're really making life hard for yourself

just up the track allocation,
you wont need to render.

cheers,
nick

Its fun being the one to find problems that no one has heard of yet...
Thanks for all the responses. I ended up just increasing the RT audio tracks and decreasing the audio playback quality to low.

All of the files were AIFFs, 48kHz, 16 bit stereo. It was the data rate that was different between the two, which I tried and tried yet could not duplicate getting the 187.5 through iTunes again. So, I have no idea how it happened or why.

So we're up and rolling again, despite. Thanks!

yeah.. we never really addressed that data rate thing, did we.
i assumed it was tied in with the sample rate

good to see it was a freak occurrence.

"audio playback quality to low"
that;s the default, BTW.
i haven't tried *very* hard, but i cant hear a difference between low and high.
but with low, you get a lot more tracks in RT.
when you do the mixdown prior to a playout or export,
that's always done at high quality.

cheers,
nick