AC-3 Dialnorm for Hi8 to DVD transfers

[Douglas Spotted eagle]

If you’ve already captured the content, I’m not sure why you’re asking about the input levels.
At -3dB, it is indeed, very hot. Are you looking to overall bring it down prior to encode, or merely wanting to compress it all at playback? For the latter, choose the Speech profile, you might scale back the overall dialog anyway by setting it to -24 vs -27, and choose an RF of speech as well. You’re doing this in Vegas for AC3, not DVD Arch, right?

Douglas Spotted Eagle
VASST
Aerial Camera/Instructor
Certified Sony Vegas Trainer

[Jacob Hobbs]

Yes, I want to set the dialnorm to bring down the volume, so DVD players can attenuate the volume properly. After setting Dialnorm properly, the reference level on the DVD should be -31db when played back.

From what I read, Dialnorm value is the average speech level in the audio track. Studios have a seperate audio track for speech, so it is easy for them to get an accurate value.

My audio is mixed, so I can’t just use the value given from Sound Forge “Scan Levels” function.

I could set the whole audio track to(-24db or -27db). This will lower it, but this is not correct. It could cause “audio pumping” when used with the Line/RF modes (Film Light, Film Standard, etc…).

Don’t the Line/RF modes only affect “Midnight mode” on DVD players?

[Douglas Spotted eagle]

I’m not sure why you’re asking the question if you’re sure of what the outcome will be? If levels are not consistent, then there is no way for the final to be predicted. I don’t use the compression modes, I set my LMP’s to “none” with dialog normalizing at -31 on everything we output. Figure out your average RMS, and that’ll give you the proper normalization level. Regardless, here are the modes/affects.

None: No dynamic range compression is applied unless downmixing could cause overload, in which case protection [compression] is automatically applied.

Speech: Appropriate for programs with predominantly dialogue.

Music Light: Applies light compression to music that is already compressed and does not require excessive dynamic range restriction.

Music Standard: Applies more compression to music that is not compressed and requires dynamic range restriction.

Film Light: Applies light compression to a subjectively quiet film that does not require excessive dynamic range restriction.

Film Standard: Applies more compression to a subjectively loud film that requires dynamic range restriction.”

These profiles are illustrated below and defined in Appendix A of the Dolby Digital encoder instruction manual which can be found on the Dolby website.

Douglas Spotted Eagle
VASST
Aerial Camera/Instructor
Certified Sony Vegas Trainer

[Valvehead]

When discussing dialnorm, the one thing that often gets overlooked is the fact that when the dialnorm level of a soundtrack is measured, it is A-weighted. This means that the midrange of the signal largely determines the proper dialnorm setting. Simply using Sound Forge or Audition to measure the RMS will get you close, but if there is heavy bass content it could give you a number too high.

Here’s a guide that has helped me understand AC3 encoding a little better: Doom9 AC3 encoding guide. It’s an older guide that refers to Acid, but it appears that the settings are the same in Vegas.

I think I read somewhere that the idea of normalizing dialog was conceived for digital broadcast. That way the perceived volume would remain consistent across programs and channels. If only something like that had been mandated for radio and CDs. Then there would be no incentive to compress the snot out of it; it would end up getting turned down in the receiver/player.

[Jacob Hobbs]

So if I just set the dialnorm in Vegas to -27db, the output on the DVD should all be set to this level?

I thought -31db was full volume, which does nothing, so -27db would lower it 4db?