AC3 + external compressor?

wumpi wrote on 12/25/2003, 3:51 PM

Scenario:
Casual holiday DV footage in stereo, with an additional stereo track for music in background

Question:
I usually apply only an EQ filter to remove some irritating noises (like the camera hiss) and a compressor to enhance voice dialogue (using Wavehammer for instance). Beside that, I leave audio untouched.

After editing, I encode my audio in .ac3. Now I ask, since the AC-3 encoder also comes with the dynamic range compressor, should I skip the first compressor (here Wavehammer)? :confused:

Help would be gladly appreciated!

Comments

farss wrote on 12/26/2003, 6:44 AM

As the wavehammer is going to give you a very narrow dynsmic range I'd tend to go the other way. Disable the compression in the ac3 encoder. The ac3 compression as I understand it is compensated during playback so you'll not get that much compression overall.

Usually I just set the line in to none and the dial norm to -27 or -31 and all works out just fine. I'd suggest doing a test onto a RW DVD just to make certain. You maybe more critical than I am.

wumpi wrote on 12/26/2003, 8:07 AM

Thanks for your quick reply, farss. Since I am not an Audio guru, and probably do more things wrong than right when applying a compressor to my voice audio track, I was thinking of removing the Wavehammer filter and completely rely on AC-3's Dynamic Range Compression and its Dialog Normalization. If you applied a compression filter, what settings would you use to bring voices forward without distorting overall sound? In this case, is a mild compression of 2:1 with slow attack and fast release generally speaking good?

As I understood (from reading a doom9 article and subsequently some Dolby material), I have to take the average RMS of my track as the value for Dialog Normalization.

In addition, isn't it the case that my DV camera (good old Sony TRV900) already applies some compression as well?

Sorry, this compression stuff is very intriguing, but also complicated for my limited mind.