AC3 Editing Levels

KelvinWorks schrieb am 06.09.2008 um 00:10 Uhr

What should I try to have my audio levels peak at while I'm editing?(not recording)

I finished my DVD that has 5.1 sound and last about 70 minutes and the volume was extremely loud on my HT compared to a commercial DVD. I had to turn done the volume on my receiver about 20 db from where I normally watch DVD’s.

I have been keeping the levels just under 0 db without ever going into the red.

Not only is the final DVD to loud but it also seems like there isn't much dynamic range between my music to dialoged to explosion FX’s. I’ve seen some discussion on the forum about the volume being soft but my volume is too loud, what am I doing wrong?

Thanks,

Kommentare

newhope schrieb am 06.09.2008 um 01:26 Uhr

There's a couple of things to consider when mixing/editing for an AC3 encode.
I'll assume your mix in Vegas has 'normal' dynamic range and whatever compression or limiting you may have used it isn't excessive.

Peaking to just below '0' is the correct approach for AC3 production in Vegas. (See other threads on audio levels for other end use situations, Broadcast etc)

However when you render the AC3 there are settings in the Dolby Digital encoder that will affect the end mix, it's replay level and can add compression to the mix if they aren't set correctly.

The first setting to consider is called 'Dial Norm'. By default it is set at -27dB. While this level will work reasonably you might want to try adjusting that setting towards -30dB by 1dB at a time and test the results. Whoops I got my self reversed and I'm post editing this section. If you set the Dial Norm lower it will actually make the signal louder. You could try going the other way but I suggest you look at the Dynamic Range settings below as I suspect they are your problem.... I didn't get that part wrong.

The dynamics are most likely being affected by the 'Preprocessing' settings which typically add 'Film Standard Compression' to the audio during the AC3 encode if it isn't set to 'None'.
It's best to turn the compression to 'None' for both Line and RF modes.
Changing these last two settings should return the dynamic range back to what you are hearing in Vegas prior to the AC3 encode.

You can also set the bitstream to indicate the type of downmix and Dolby Surround Mode you want where your DVD is replayed on a system that doesn't have a Dolby Digital amp or whether you want a Dolby Digital EX system to activate the surround back speakers correctly.

These last settings shouldn't affect what you are currently hearing but are other settings you should be aware you can adjust.

Hope this helps

New Hope Media
(Edited after it I realised my error on Dial Norm)

musicvid10 schrieb am 06.09.2008 um 01:37 Uhr

1) Play through the entire timeline in Vegas. Pull your levels down if ANY of the 5.1 channels peak out. I prefer to leave the master faders at 0dB and adjust my track levels up or down to compensate once I've got the surround pan where I want it.

2) When rendering, choose AC-3 Studio, not AC-3 Pro, and choose the DVD template with AGC off. The Pro template has way too many parameters to get confused over, and it has been demonstrated that it will still compress under certain circumstances even when you think it's off.

I've been in the audio and music end of the business for three decades, and for a natural sound the AC-3 Studio encoder is simple yet quite sufficient. JMO

newhope schrieb am 06.09.2008 um 06:04 Uhr

JMO's 'keep it simple' approach by using the AC3-Studio encoder with AGC off is probably the best if the AC-3 Pro encoder is giving you problems and/or your not an audio professional.

Of course having the choice of the AC-3 Studio or the AC-3 Pro encoder is only something that has become available in later versions of Vegas so if you are still using Vegas 4, 5 or 6 you'll need to deal with the 'Pro' version as there is only one choice available and, although it isn't called the 'Pro' version, that is what it is.

I similarly have been in the audio industry, film and television in my case, for over 30 years and have the benefit of having completed the Dolby Digital - Broadcast and Professional Audio Training Course back in 2001. Hence my answer tends to deal with the Pro encoder as I choose it in preference to the 'Studio' version in Vegas 8 Pro.

In fact I mixed a 30 minute short feature in my own studio using Vegas 7 (pre 8 Pro) in Dolby 5.1, encoded it with the AC-3 Pro encoder and won The Best Achievement in Sound for a Short Film in 2007 awarded by the Australian Screen Sound Guild. Check out 'Death's Requiem' on iMDB for more details.

Still now you have the info to make the choice of the studio or Pro encoder to suit what you want.

Regards
New Hope Media

KelvinWorks schrieb am 06.09.2008 um 14:33 Uhr

Thank you for your replies. I have Pro 8 and would like to figure out how to use the tools availble so will do a few more test.

JMacSTL schrieb am 15.09.2008 um 18:20 Uhr

Although simpler and less confusing, i find that when using the "ac3 studio" setting, the LFE doesn't playback on a DVD. Odd.

jmm in STL

newhope schrieb am 16.09.2008 um 00:08 Uhr

"the LFE doesn't playback on a DVD"

If you are using the AC-3 Stereo preset the LFE channel is not included the format is 2.0 and the .0 means no LFE.

The 5.1 preset should include the LFE channel, assuming your mix in Vegas has assigned signal to the LFE channel of course.

I don't use the AC-3 Studio encoder normally so can't confirm it does.

The AC-3 Pro encoder, which I use in preference to the Studio version, certainly does encode the LFE channel in formats where it is indicated... basically any preset with a x.1 format where the.1 indicates the LFE channel.

New Hope Media