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Old November 18th, 2010, 01:55 PM   #1
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Questions about 12-bit Audio

Hello all!
Before my question, I'll say one or two things.
I'm absolutely new to posting on this site, but at the same time, I've been reading here for any camera issue I've had for over a year. Any issue I've had, I've been able to read it here and find a solution.

I'm really posting out of necessity, and I don't know where else to go.

I have a small personal business of filming live shows for the downtown scene, and since I really don't have the money, I borrow all of my equipment from family and my media teacher. I'll skip ahead to where it matters.
I was filming a particularly important show (last set before the band goes on a year hiatus), and I had 4 cameras running, most notably, 2 Canon GL2's. One 1 camera of the 4 really had solid enough levels set to warrant using it for the overall audio... the issue I'm having is that I had stupidly set it for 12-bit audio with a 32 sample, instead of 16-bit, 48.

I now know this was a bad decision, but now I have no idea what to do. Every time I render the audio using Premiere Pro (or even try to view it), the audio comes out horribly - everything sounds like it's 8 octaves lower than the original. It all matches up with the video, but it is irrecoverably damaged - yet I can watch it in a simple program like windows media player and it works fine. I also have the original source audio and video - extracting the audio has the same outcome.

I do understand the concept of not being able to render up a step, only down, but I'm wondering if there's any way around this.

How would I be able to use this audio without being able to render it? Is there a method or program I am not aware of that can adequately render 12 bit? Is there any way I can have a preset in Adobe Premiere Pro so that I can edit 720p, 29.97fps footage while using 12-bit audio?

I've considered recording the sounds that come out of the sound card, but they sound like it's coming through a tube. I attempted to record it through Soundbooth, but every time I use the only working sound recording method, the very loud hum takes over the audio in less than 5 seconds.

Sorry for all these issues, I'm just really lacking options and have no idea what to do.
Thanks for bothering to read it!
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Old November 18th, 2010, 02:47 PM   #2
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Without being familiar with Premiere Pro, you're faced with two methods:

1) Somehow reset your PP project audio properties to 32KHz instead of 48KHz. This may or may not be possible, but is the preferred method if PP will do it.

2) Resample your audio to 48KHz outside of PP. Perhaps Audition will do this for you. Then, bring in your resampled audio and line it up with picture in PP. You may have to unlink and delete the original audio track in PP for this to work. Resampling would mean rendering new audio clips at 48KHz.

If the first method works, you're back editing quickly and painlessly.

If you do have to go to the second method, don't do anything destructive of files or work you've already put in. Make backup copies of your media before you start, make a backup copy of your project too.
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Old November 18th, 2010, 03:53 PM   #3
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Thanks for the response!

anyway, I do not think that 1) is possible, but I do know people who are much more experienced with it than I am, so I'll look into it. At first glance, I would agree with you and say that it is most likely my best bet.

In terms of resampling, I'll have to look into that. I didn't think about that as being a viable option, so I'll look into it immediately. Quite frankly, needing to take 5 minutes at most to re-synch it all is the last of my worries, so either one I'm okay with. Thankfully rendering audio isn't as horrendous as rendering video + audio.

Like I already mentioned, thanks a bunch of the response, and I'll be eternally grateful if it works out!
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Old November 18th, 2010, 04:52 PM   #4
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Might try this:
1. Right click the clip in the PPro browser window. Select Edit in Soundbooth > Export audio
2. When file has opened in Soundbooth, select Save As. Select .wav format
3. Click on save, then select 48000/16bit in the option box that opens.
4. The converted file will show up in the PPro browser window with "extracted" appended to name
5. Unlink original audio, delete that track, drag the extracted track in its place.

(I do not have a 12-bit file to practice with but I assume the resample function in SB will handle it)
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Old November 18th, 2010, 05:05 PM   #5
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Specifically "edit in Soundbooth"? The issue with that currently is I have the only option of "rendering and replacing". Would that be adequate? I'm trying your method now for the sake of things anyway, though. Thanks so much!
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Old November 18th, 2010, 06:57 PM   #6
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I suggest you convert it using MPEG Streamclip (a nifty little app made by some Italians).

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Old November 19th, 2010, 01:30 PM   #7
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Reason for the round-the-barn approach I suggest is often the edit options are greyed out when you select the audio track from the time line, I don't know why. If you open the clip from the browser it should work. however, if you can, there is an advantage in sending to SB from the timeline --the audio clip is automatically replaced on the timeline track in synch.

BTW +1 on mpegStreamclip, excellent freeware. It does all kinds of wonders. VLC is also a good option. They are, of course, external programs which complicates the process a little, but whatever works...Audacity, also excellent freeware, can convert data rates also. I take from your comment in your op that you're thinking you can't resample up --- you can in audio bit rates, it just restates the data you have in another way.
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Old November 19th, 2010, 01:35 PM   #8
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certainly you could bring it in as a 32K clip, but it might just be easier to start a new project at the correct audio sample rate, then simply export the audio track to a separate file. Then reopen the original project, dump the audio track causing problems and sync up the new audio track. A lot less bother - and you could treat it as a just a new audio track, or group it if you need to move it around a lot.
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Old November 20th, 2010, 10:38 PM   #9
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My issue so far is that no matter what sample I bring it in as, the audio is still seriously messed up. I'm going to look over it just to see if there's anything I'm doing wrong in terms of presets, just to be sure.

How do I change the preset's audio rate, while keeping the video at the desired size?
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Old November 20th, 2010, 10:57 PM   #10
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Peter, can you post a sample? maybe we can determine your problem better...
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Old November 21st, 2010, 09:44 AM   #11
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I was just thinking of that, here it is!

http://www.mediafire.com/?i248t7ijiwfaqh4

This is about a minute of what the audio sounds like after it's rendered. I would show you what the original source audio sounds like, but that's physically not possible for me. I would try exporting just the audio, but it comes out like that every time. I even tried something basic like audacity, but the file is just so massive that it would take "1193046 hours, 27 minutes and," as of now, "3 seconds."

Also, something I think would be worth mentioning (and confuses me a little, I won't lie) is the fact the file is, in properties:
16-bit, 32 sample.

I can't remember if the bit depth is directly connected to sample size, but I think it's worth mentioning.

Quote:
Originally Posted by Peer Landa View Post
I suggest you convert it using MPEG Streamclip (a nifty little app made by some Italians).

-- peer
Oddly enough, it doesn't have an .avi file support, which is what the original file is.

Quote:
Originally Posted by Paul R Johnson View Post
certainly you could bring it in as a 32K clip, but it might just be easier to start a new project at the correct audio sample rate, then simply export the audio track to a separate file. Then reopen the original project, dump the audio track causing problems and sync up the new audio track. A lot less bother - and you could treat it as a just a new audio track, or group it if you need to move it around a lot.
I tried that the other day. Every time I try to import the file into the new project with what I figured would be the correct audio preset, it just switched over to the original audio and left the new project blank. It wouldn't let me import the audio into that project.

Quote:
Originally Posted by Battle Vaughan View Post
Reason for the round-the-barn approach I suggest is often the edit options are greyed out when you select the audio track from the time line, I don't know why. If you open the clip from the browser it should work. however, if you can, there is an advantage in sending to SB from the timeline --the audio clip is automatically replaced on the timeline track in synch.
Battle, I tried your original suggestion of resampling, but the result was still the same - in fact, there was no audible difference between the two. I'll admit, I'm kind of losing hope for this.
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Last edited by Peter Howie; November 21st, 2010 at 10:49 AM.
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Old November 21st, 2010, 11:52 AM   #12
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Quote:
Originally Posted by Peer Landa View Post
I suggest you convert it using MPEG Streamclip (a nifty little app made by some Italians).
Quote:
Originally Posted by Peter Howie View Post
Oddly enough, it doesn't have an .avi file support, which is what the original file is.
Since this is an audio issue, use MPEG Streamclip to convert the audio track to the format you want (16/48, or whatever) and then replace the old track with the converted Streamclip audio.

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