track Compressor

neb wrote on 7/14/2005, 7:23 AM

I am just now finally getting my mind around the audio track compressor and how compression really works, and I still have a lot to learn about audio in general, so I have a quick question.

I am working on some footage that has an extremely wide dynamic range. Basically it was a group of people standing in a big circle talking. The camera (which is a cheap camcorder with a less than great mic) was on one side of the circle. So of course the people who are fare away are very quite while the nearby people are very loud. So i add a compressor. In order to get the quite people loud I have to push the input gain a lot, but this means that the input level is peaking at 6-8 when the nearby people talk. So then I just compress the heck out of it with the threshold and reduction and get everything into an ok range and the output level never peaks. So here is the question: is it really bad that the input level is peaking so high? I am so used to thinking that peaking is really bad, but is it that big a deal when it is not the actual output?

Thanks for your help

Ben

Comments

farss wrote on 7/14/2005, 7:41 AM

So long as the output is not going over 0dBFS then there's nothing technically wrong with hitting 0. One use of compression is get the average audio level pushed up hard against 0dB, that's how commercials are made to sound LOUDER than normal program.

All that said though I'd suggest using a volume envelope to try to get the levels a bit closer together before using compression and I'd pay a bit of attention to attack and decay times to avoid it sounding like it's been heavily compressed. Biggest problem with deep compression in your scenario is the noise floor will come up and also you might start to hear a sort of pumping or breathing effect.
Some Eq before the compression so just the voice part of the spectrum is coming through will also help.

As you were using an on camer mic and I assume it was stereo you might find that there's some separation between the near and far speakers across the channels. If that's the case try splitting the channels, make a duplicate of the audio track and switch one track to Left Only and the other to Right Only, now you can treat them differently and produce a mono output, the original stereo image will be a mess anyway.

Bob.

Spot|DSE wrote on 7/14/2005, 7:49 AM

I'd recommend you copy the stereo track with people loud on one side and quiet on the other, to a new track. Then right click the top track, choose Channels>Left Only. Then right click the bottom track, choose Channels>Right Only.

Run the compression on only the louder of the two, perhaps try normalizing the quieter of the two and use light compression there, too.

There is more to be done, but if you're just getting started, this will be a good place to get familiar with the tools.

neb wrote on 7/14/2005, 10:49 AM

thanks for the help...i have lots of work to do...

ben