AC3 Center Channel Issues...

psm9640 wrote on 2/25/2004, 2:23 PM
Hey folks -- I've recently been working on a 5.1 mix in Vegas of a film we shot in the fall and I've noticed that after creating the AC3 audio track, burning the DVD, in some instances the center channel, although SOMEWHAT audible is really too low. The latest system I tried the DVD on is a very high-end surround authoring/playback studio (it has the Pro Tools Edit Pack there but the DVD player is routed separately to the speakers).

Initially we did a surround mix in Pro Tools and then encoded to AC3 via the A-Pack plugin and I was not thrilled with the results, hence we came back to Vegas. I've opened the Surround Panner in my VV project and double-checked the center fader on the dialogue track and it's set to 0 db (which is where I want it), and when I play the project file mix, it's absolutely flawless. I'm just wondering if anyone else has encountered this issue. I just don't want to have to fan out dialogue into the L/R when it's not motivated by on-screen actions or movement.

Looking forward to some insight. Thanks!

-PM

Comments

RichMacDonald wrote on 2/25/2004, 2:53 PM
I need to play this back to you:

Your Vegas edit is perfect, but the center is too low on your DVD.

1) Try playing the DVD on the same computer you did the editting on. This will eliminate the possibility that its an artifact of your playback system.

2) Check the settings in the "render as" ac3 template. I don't have it in front of me, but there are a number of settings which could affect this. Hopefully, others can chime in with something specific, but this is a start.
cosmo wrote on 2/25/2004, 2:53 PM
What app are you using to encode the dvd? I would want to see a DVD properties to be sure ac3 was going to disc, for starters. I would also probably do a test tone ac3 file going speaker to speaker just to see what happens and where the signal is lost. This would tell you if your process was working at bare minimum. Also I would drop one version of the ac3 on the dvd as a music file and one attached to a video...maybe there's a difference there? There are properties in Vegas too for the ac3..check 'em!

Strange problem...I've never had it. Usually the center channel problem has to do with the convergence slider but you've got that covered...
psm9640 wrote on 2/25/2004, 4:09 PM
Thanks guys -- I'll go through the settings again on the Vegas Export. I was using the default template for AC3. Does anyone have any thoughts on changing the dialogue setting from the default of -27db?

I used DVD Architect to encode the DVD. Will let you know if I have any breakthrough's on this!

-PM
cosmo wrote on 2/25/2004, 4:17 PM
Good luck. As for the -27 thing, I've never changed it. I usually drive up the meters pretty high and my levels on my system are about the same as any other DVD I have. Just fyi....
MJhig wrote on 2/25/2004, 4:29 PM
I much prefer to mix my audio entirely in Vegas before rendering the video to the DVD-A template and the audio to AC-3 separately. I don't want DVD-A to change the work I did in Vegas.

Edit;

In *Vegas' AC3 template* I set the dialog norm to -31 and on the last page *Processing* I turn off all the effects whatever they are... working from memory here but that's basically it to keep the mix I did in Vegas unaffected.

*Then my mix will not be affected during the encoding and DVD-A will not re-render.*

MJ