how to normalize AC3 files...

TeeJay wrote on 11/22/2006, 4:23 AM

I find that Stereo AC3 files are considerably lower in volume than anything else.

I foolishly just forked out my hard earned cash to buy Sound Forge 8, thinking that it would allow me to open an AC3 file for editing, only to disappointedly find that it can't...

So how can it be done?

Comments

GeorgeW wrote on 11/22/2006, 5:17 AM

A tip I saw from Edward Troxel about low-volumes for AC3 files:

<<<
When rendering to AC3 format, the volume will be automatically reduced. If you wish to prevent this from happening, make the following setting changes:

Change the dialog normalization to -31

On the PreProcessing tab, change both the Line mode profile and RF mode profile to NONE.
>>>

SimonW wrote on 11/22/2006, 5:25 AM

Actually, one of the best ways to make sure that the dialogue is not too quiet is to first of all render the dialogue channel sound out into a WAV file.

Then load it into Sound Forge and go to the Normalise dialogue. Select Average RMS, and then go to Analyse. It will then tell you the average volume of the sound.

Now when you render out the AC3 file from Vegas, set the dialogue normalisation to the closest setting to the average result you saw in Sound Forge.

gordyboy wrote on 11/22/2006, 6:46 AM

I think it's very little to do with the normalisation of the source audio tracks on the timeline and everything to do with the default settings for AC3 renders.

GeorgeW has posted the solution - and it works a treat. I have this as my default for AC3 renders now - previously I was most disappointed in the level coming of my DVDs, particularly when compared with commercially pressed discs.

Cheers

gb

farss wrote on 11/22/2006, 11:30 AM

Technically what Simon is saying is correct, you should do that as well as setting the preprocessing to None. If you don't have a way to separately process the dialogue then use SF to just read the RMS value of your soundtrack and use that as the dial norm value in SF.
If you don't have SF or if your work is not for theatrical release, what the heck, set it to -31dB.

Serena wrote on 11/22/2006, 6:06 PM

Spot recommends (see, I did pay attention) to setting Dialogue Normalisation to -31dB and Dynamic Range compression (both line mode and RF mode) to "none".

SimonW wrote on 11/23/2006, 8:48 AM

I would recommend against blindly setting it to -31. Certainly for good sound mixing.

The reason that Dolby include this dialogue normalisation option is to make sure that the sound plays correctly in relation to reference level no matter which DD equipment you are playing it on. But this can only work properly if it is set to the correct setting.