Reverb reduction ?

rtbond wrote on 12/29/2003, 6:03 AM

Hi,

I'm a Vegas and live recording newbie. I recently made a live recording with my Digital 8 camera and a pair of external mics (Rode NT5s) in a large room. The recording has a lot of natural reverb, which I'd Iike to find a way to reduce in post production.

The recording is of a 3-piece rock band (vocal, keyboards, electric violin, and drums).

Any suggestions on what I might try using in Vegas (or using 3rd party Direct-X plugins with Vegas) to help reduce the natural reverb in the audio track?

Thanks!

--Rob

Comments

farss wrote on 12/29/2003, 8:19 AM

Wow,
mics worth more than the camera, I'm impressed!
Getting rid of something in audio is MUCH harder than adding it in.
I've faced a similar but much worse problem. The suggestion I got which I wasn't able to try was to use Acoustic Mirror in subtract mode. You'll need Sound Forge for starters which now ships with it, also come bundled with Noise reduction which you might also need as D8 cameras are not reknown for low noise audio.
Having got Acoustic Mirror you then need to record the venues acoustics using impulse sounds that come with AM. I'd suggest putting the speaker where the band was and using the same mics in the same location to record the impulses. You then feed the recoding into AM and it'll do its thing.
I was also told you can try to guess the room parameters without recording the acoustics but this may need lots of experimenting.

I've done none of this myself and only recently acquired SF so I just haven't had time to try AM, I need some extra gear to give it a good workout.

rtbond wrote on 12/29/2003, 8:52 AM

> Wow, mics worth more than the camera, I'm impressed!

Actually, you can get a matched set of Rode NT5s for under $300 dollars, but you are right the mics are a bit of overkill for the relative audio quality provided by the Digital 8 camera.

Interesting technique you reference using the Sound Forge Acoustic Mirror. This is probably something that is currently out of my reach, but good to know about nonetheless.

Any other "less scientific" (less robust) approaches to mitigating the natural reverb of a room.?

Regards,

Rob

bgc wrote on 12/29/2003, 9:51 AM

getting rid of reverb is quite a hard thing to do - there aren't any easy solutions. i think they're are quite a few people doing research on how to do this, but i don't think there are any products, maybe do some google searching?
also I've never heard of using sound forge and acoustic mirror and a room impulse in negative mode. sounds kind of cool!
B.

farss wrote on 12/30/2003, 3:38 AM

There was I think another suggestion that goes way back and you could do this in Vegas.
Add compression to the existing track, make a copy, invert and add. Remove compression from original track.
The trick I'm told is getting just the right amount of compression and just the right mix to get just enough cancellation. I think the trick also required slippig the new track a few milliseconds.

Anyway you have all the tools to try this in Vegas and you can do it on a short sample. have a play around, cannot break anything. Great thing with Veags is youcan do a lot of this pretty well in real time and monitor how it's going.

tmrpro wrote on 12/30/2003, 12:01 PM

If you narrow your stereo field you should be able to effectively reduce the apparancy of the room's natural reverberation.

If you have a stereo file, you can create two mono files of left & right.

Open the two mono files in Vegas.

Take the two mono tracks and instead of panning hard left and right, bring each side in from 100% to 75%. See if that does it.

You can vary these settings and find where it works best.

You can also use the Waves S1 Imager as a plugin and reduce your stereo spread on a stereo file by percentages.

But in either case, by reducing the stereo spread, you should reduce the apparancy of the reverb from a stereo recording.

Hope that helps!

rtbond wrote on 1/2/2004, 8:34 AM

Thanks for the suggestion.

A followup question. Why in Vegas are the audio signal levels about 6 dB higher after I

(1) copy the original stereo audio track
(2) set one audio track to "Left Only" and the other to "Right Only"
(3) and then pan one mono audio track 100% left and the other 100% right?

I am trying to create two mono audio tracks from the original stereo track, and then adjusting the stereo separation between the two mono tracks.

I'm sure this is something simple.

Thanks!

---Rob

drbam wrote on 1/2/2004, 10:13 AM

>>Why in Vegas are the audio signal levels about 6 dB higher. . .<<

This is explained in the manual - when you pan fully L or R, Vegas increases the signal 6 db. I wish it didn't but its just the way it works and has been this way since version 1.

drbam

SonyEPM wrote on 1/2/2004, 11:13 AM

Right click on the pan fader and select "constant power"-

drbam wrote on 1/2/2004, 12:38 PM

>>Right click on the pan fader and select "constant power"-<<

Ahhh. . . learned something new! Thanks! ;-D

drbam