Audio question for the pros

blk_diesel wrote on 11/1/2006, 2:31 PM
I recently recorded my first concert with my FX1. I set the audio to auto for half the show and manual the last half. I noticed that at times when the music gets really loud, there are some distortion clipping. It's present when I had the audio set to manual and the level at 3-4 so the the meters were well below peaking.

I'm used to using a GL-2 which has an attenuation switch which prevents distortion. Is there a way to clean up the distortion?

Comments

farss wrote on 11/1/2006, 2:41 PM
If the clipping is not too bad then Sound Forge has a Clipped Peak Restoration tool that can do wonders. If things get seriously out of hand all bets are off.

Depending on the nature of the clipping you may find that that tool does nothing. Dispair not, it needs to see hard digital clipping before it'll do its thing. SO you might need to increase the volume by 0.1 to 0.5dB to force hard clipping then the restoration tool will work.

Bob.

PS. For complex sounds hm, HDV audio isn't too good. I double head into a HDD recorder, record at 24/48K with the gain down a bit, plenty of wiggle room to then bring the levels up in Vegas. Sounds great if you can get a good feed from the desk.

PSS. I'd render your HDV to a new 16/48 track before sending it into Sound Forge.
blk_diesel wrote on 11/1/2006, 3:45 PM
I searched the help menu in Soundforge and didn't see any subjects on "clipped restoration". Ca you give me a quick way to access it? Also, I used the in-camera down converter to capture the footage in DV mode. My HDV chops are not up to standard by any means.
farss wrote on 11/1/2006, 4:03 PM
Just in case you didn't realise this, downconversion although it means you audio is now 16/48K, doesn't improve the quality of what was recorded, that's when the damage got done.

In SF,
DX Favourites. If you don't see Clipped Peak Restoration.
DX Favourites > Organise.
Browse to Clipped Peak Restoration, RClick, Add to DX Favourites.

Probably better ways to add the plug but that's how I've done it.

Edit:

Just realised also the Clipped Peak Restoration plug is part of the Noise Reduction package. If you have the NR2 package you should have it.
blk_diesel wrote on 11/1/2006, 5:08 PM
OK, I found it, now I'm playing around with the controls. So far, I've tried it at 3db and 6 db just to get a feel. I'm still hearing some distortion or muffled sound, but hopefully, I can make a few adjustments and reduce it. Thanks for all your help and if you have other suggestions, please give them. I've kind of concentrated on video and neglected the audio aspect of editing.
farss wrote on 11/1/2006, 5:40 PM
Also in SF there's a Clipped Peak Detection tool.
If that tool finds no clipped peaks then the Restoration tool will do nothing.
I like to zoom right in and have a look at what I'm trying to fix, both before and after I've done the restore.

Probably not applicable in your case but sometime with clipping in analogue land you can find further down the chain someone has tried to compensate to no avail by turning their gain down. In this case again you need to make matters worse by forcing hard digital clipping in SF to get the tool to kick in. The Volume FX in SF is quite good for doing this.

Anyways it's all good fun.
But as always fun I'd like not to have at times, like one recent one where someone had fed line level into a mic input. The camera had AGC on so probably on the meters it didn't look too hot. Needless to say the audio was beyond help.