General Audio & AC3 question

Markk655 wrote on 4/6/2009, 11:56 AM
I am using an AVCHD camcorder with 5.1 DD audio. I have another audio track with my soundtrack (mostly mp3s) and set to the center of the sound field. I seem to get a much lower volume of the soundtrack and some of my main audio tracks once I render (NTSC widescreen DVD with AC3 audio compared while I edit. Is it just a case bumping it up to ensure the final product is audible?

1. I understand that I should not exceed 0 dB as it will be cut off. I have seen a suggestion of -6 dB as a suggested peak level. Is this what others are using?

2. Should I "normalize" my audio or main audio? If so, what should I normalize it to? The default appears to be -0.1, Perhaps, I should change that to -6dB?

Thanks!

Comments

c.s.p productions wrote on 4/12/2009, 11:31 AM
The same thing happens when I import audio in center. I think it is because the speakers are on the right and left tracks with no center speaker. This should not be the case when played on a DVD player.
To answer your questions as best I can:

1. You can exceed 0dB. -6dB? that seems a little quiet if you want the sound to be foreground.

2. I normalize all of my audio and then adjust in Vegas. You Normalize to 0dB. If you listen any song, the sound is at 6dB (I think)
You should be normalizing at 0dBs, though
musicvid10 wrote on 4/13/2009, 8:51 AM
"You Normalize to 0dB. If you listen any song, the sound is at 6dB (I think)'

It looks like you are confusing dBVU and dBFS.
dBVU is an analog broadcast scale, not widely used in digital environments except for legacy references.
dBFS has a hard ceiling, 0dBFS. Exceeding that means you have clipped the output.

Depending on which legacy reference flavor you use, 0dBVU = -18 or -20 dBFS (usually -18dB).

There is also the difference between peak and average levels. Acoustic music with -0.1 dBFS peaks may have an average (RMS) level of -12 to -24 dBFS. Highly compressed rock / metal source with the same peak level, might have an average level of -6 to -9 dBFS, which is extremely loud!

This is a complex area, and there are no simple rules for digital recording / editing except you must keep your peaks below 0dBFS. Any compression that is applied to raise the average levels is a matter of experience and taste.

EDIT: Before we get into another lengthy discussion on compression, the conventional advice is "less is better."
Markk655 wrote on 4/17/2009, 10:26 AM
Thanks for clarifying.... One (or 2) more question, is there a way (envelope) for front/rear panning? Or a way to key frame that in an audio track that is set for surround? Essentially, I would like to be able to pan front/rear over time on a given track - akin to the left/right panning.
tag313 wrote on 7/24/2009, 7:46 AM
Did you ever figure out how to pan front/rear?

I am looking for a way to do that as well.
musicvid10 wrote on 7/24/2009, 8:12 AM
http://www.sonycreativesoftware.com/moviestudiope/compare
Markk655 wrote on 7/25/2009, 1:23 PM
Would that be "5.1 surround mixing including film-style panning"? only found in pro version?

Seems like I shouldn't have to be a pro to be able to pan to the rear.

Hopefully they'll give it to us in VMS (n some version) in V10.
tag313 wrote on 7/27/2009, 9:50 PM
pro version only as it turns out. I've become obsessed with it, so I bit the bullet and upgraded. It works great!