Bizzare issue with Audio Levels over Firewire.

I've got a head scratcher that any input an advice on would be most appreciated:

A few weeks ago we digitised in a large project - with several computers going at the same time - one was digitising via an AJA IO over SDI and two others were capturing over Firewire directly to the crate. all footage at 100% Res.

A large percentage of the Audio captured during this time is there, but the levels are a fraction of what they should be. On playing the tape back on the deck and monitoring it both over speakers and via a pair of headphones the audio levels seem fine - yet when viewing the source quicktime file the levels are very (and i mean very) low.

Footage taken in on the DSR over SDI seems to be fine - its the footage captured over firewire that seems to be the culpret. However at this point i get baffled. To go through the checklist...

I've checked the source media ie ruling out playback or anything related to final Cut when viewing the media. the footage has been captured with low levels and thats a definite.
However, as far as I'm aware you don't have much control over audio when going over FW or SDI, its not like we're talking analogue here and the levels have got knocked! How can it be that when viewing the tape the levels are fine - yet after capturing that audio over firewire (standard firewire capture preset in FCP - its never been a problem before) suddenly we're struggling to get any audio?

Does anyone have any explanation or any advice as to how i might locate the problem?
Many thanks

Josh

How low is really low? The meters in Final Cut go into the 90s, so where are your tracks?

To be clear, you capture the **same tape** via SDI and then FireWire and they don't match?

<<<its never been a problem before>>>

Can you recapture one of those "before" tapes? Go shuffle around your desk and see if you can find one of the older tapes that used to work.

<<<you don't have much control over audio>>>

Not unless you have a very large Broadcast machines that can change levels on the fly--in and out--but generallly no.

Just listening to the deck on headphones is the only way you have to tell if the tapes are normal, right? Again, I'd love to go back to one of the earlier OK tapes and play that. It's no surprise your ears aren't a very good judge of level, but they do much better if you can play a really good tape and then a mystery tape back to back.

Koz

<<How low is really low? >>
Well on parts of the footage on the tape it peaks, in Final Cut the levels are struggling to come of the floor.

Same tape - originally captured over firewire directly to G5. then re-digitised on a DSR via AJA IO

haha no its definatly not a large broadcast machine... i believe was a small DV Camera to be exact!

<<Just listening to the deck on headphones is the only way you have to tell if the tapes are normal>>
Well no, listening to it on the deck, looping it through PPMs and checking the levels on the front of the DSR - my ears arn't perfect but i've been a musician for 20 odd years and to be quite honest even a tone deaf rapper could tell that the footage captured over firewire hasn't got the correct audio levels.

Its stumped several engineers, editors and just about everyone else within earshot!

I'd give anything if you could find one of the tapes that "used to work."


Experiment: Close everything. Open QuickTime Pro--I believe you should have Pro if you have Final Cut. I think it's automatic.

Connect the camcorder via FireWire and put one of the tapes in the machine. Press play.

Launch File, New Movie Recording, Device Native. Press Record. Stop. Wait a bit and then play it back. Did you get sound? You may get sound when the preview window opens before pressing Record. I forget.

If that worked, then I'm betting your Final Cut is set to capture the wrong two audio channels. You can capture four channels of DV audio, but you can only capture two of them at a time. If you're set to capture 3 and 4, then you are listening to the -89 dB audio crosstalk inside the camera. It's possible the 48/32 setting is wrong, too.

It's also possible you won't know you have this problem if your preferences are scrambled. I would trash the Preferences and set up the project, sequence, and capture again. I don't remember the Trash process, but a search of the forum should tell you.

Koz

<<I'd give anything if you could find one of the tapes that "used to work." >>

Sorry you've lost me there, i've seen hundreds of tapes go through fine, levels correct etc etc, and the guys doing this have never reported any problems to me.

I'll have a nosy around tomorrow, problem is i wasn't the one digitising the stuff, and it happened a while back, im just the one given the job of working out what went wrong!!

Im pretty sure they'd have been using the 'easy setup' DV Pal Capture - but i'll try and find out some more details. Thanks for the input!!

<<<i've seen hundreds of tapes go through fine>>>

Great. Do it again. Find a tape that used to work and re-digitize a small segment of it. I bet it doesn't work.

<<<Im pretty sure they'd have been using the 'easy setup' DV Pal Capture>>>

Also Great. However, if the Final Cut preference system was damaged, what you selected and what you got weren't the same.

Try the QuickTime capture thing. That will get you away from all the odd things that Final Cut does.

Koz

gotcha, will have a look today cheers!

I think Koz has got it figured out right there. That just occured to me this morning, so I logged on to post it, and he beat me to it.

Kozikowski Wrote:
-------------------------------------------------------
> If that worked, then I'm betting your Final Cut is
> set to capture the wrong two audio channels. You
> can capture four channels of DV audio, but you can
> only capture two of them at a time. If you're set
> to capture 3 and 4, then you are listening to the
> -89 dB audio crosstalk inside the camera.

travis ballstadt
www.thrillcateditorial.com

G5DP2.5ghz, 4.5gbRAM, 2TB external SATA, Panasonic AJ-D455, G4PB1ghz, 15", 1gbRAM

Well i got an update from the editor the other day, it seems after checking a mirror of one of the drives he's working on that the QT files on the mirrored Drive are fine My head now hurts as this media is the same, copied from his drive onto another...

Unfortunatly i can't look at the setup the guys had when the stuff was digitised - but what confuses me if that is the cause, is that it is a handful of tapes out of over 700 that are wrong - so how/what happened for the settings to get messed up and the to end up with the audio crosstalk inside the camera?

only thing to do (when i get the chance) is to pull the two drives together, find one of these 'bad' clips and compare them both side by side.... I just want to make sure this doesn't ever happen again, its just frustrating that the stuff was digitised so long ago.

i'll report if i get anywhere and get to look at the two drives.
My head really hurts...

I'll bring some strong painkiller (like vodka) in to you tomorrow mate to ease your weary head!



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