Vegas + DVDA audio formats

mel58i wrote on 7/7/2006, 7:03 AM
Up to recently I've been making dvd's using TMPG author and using vegas template "dvd pal" to give a MPEG2 multiplexed file (MPEG audio).
Because of the better features of DVDA I've decided to learn it.
Because of restrictions DVDA will only accept LPCM or AC3 for the audio and anything else presented to it (like MPEG audio) will be re-compressed to the above formats.
I believe that the chosen route is to render vegas avi's into an MPEG2 video stream and then render into AC3 audio stream to avoid DVDA re-compressing.
I have discovered that vegas AC3 render produces an audio file with lower volume that its counterparts, although by customising it can be brought to a proper level.
If a multiplexed MPEG2 is brought into DVDA and AC3 is specified the resultant re-compress is down in levels again. Does DVDA use a seperate AC3 codec than vegas or is there a way of customising it?
I suppose what I'm asking really is what the preferred method is for getting audio into DVDA. With my old workflow I could open up my MPEG2 and check it A&V before building a dvd file. My system won't open an AC3 file so cannot be checked.
Thanks Mel. (UK)

Comments

farss wrote on 7/7/2006, 7:25 AM
Change the following ac3 encoder settings:

Line mode profile = None
RF Mode profile = None

Dialog Normalization -27dB (if not already)

Bob.
TheHappyFriar wrote on 7/7/2006, 10:21 AM
why do you want to change the line & RF modes?
farss wrote on 7/7/2006, 2:41 PM
Because if you don't then the ac3 encoder turns the level down something fierce.
This is pretty old news I believe from back in the DVDA1 days, maybe it's out of date?

Bob.
rs170a wrote on 7/7/2006, 6:07 PM
Dialog Normalization -27dB

Bob, isn't that supposed to be -31?
That's what all the posts I've read, such as this one, have said.

Mike
TheHappyFriar wrote on 7/7/2006, 6:23 PM
I got in to DVDA on v3. :) I'm out of date!
Steve Mann wrote on 7/7/2006, 11:05 PM
My understanding is that this is not a limitation because the DVD Specification (MPEG.org) requires the audio to be Dolby AC-3, Linear PCM or MPEG2 Audio (audio on;y, not multiplexed).

farss wrote on 7/8/2006, 12:51 AM
Good point,
Although 4dB isn't that huge a difference.
But here's the odd thing. I've tried it at both -27dB and -31dB and the levels look the same judging by the waveforms in DVDA. However setting it to -21dB and there's difference in the waveforms in DVDA. That doesn't seem to tie in exactly with what's being said I think.

Now the other piece of advice was to set the dial norm to match the program content. The simplest way to do this I was told was to measure the RMS level of the program using SF's statistics tool. That's not strictly the same as the dialogue normal value but pretty close.

Perhaps the only real way to know for certain is the measure the output on DVD player using some test tracks.

All in all fairly confusing.

Bob.