Rendering audio corrctly from Vegas for DVDA3

wm_b wrote on 6/13/2005, 4:28 PM

I have been trying to figure this out on my own but haven't quite solved it yet. I'm getting close to finishing a project that is a live band performance shot in my recording studio. All the audio is mixed and synched to the video. When I render to mpeg2 with the DVDA NTSC video stream it does not include the adio. When I select to include the audio it is rendered to AC3, I think.

In any case, when I prepare it in DVDA it tells me the audio wil be recompressed. Sometimes it will tell me the bit rate is too high for some players. The DVD's have been playing fine in most machines.

So whats the deal? Is there another way to do the audio. Since it is mostly about the music I want the best audio quality possible. Currently the Audio is 48k, 24 bit wave files. How should I go to DVDA with it. PCM or AC3? What bit rate?

I would like the video quality to be a little better too but that's for another time. At the moment I just want to get this done in time for Father's Day.

Thanks, William

Comments

alk3997 wrote on 6/13/2005, 4:36 PM

It is a bit confusing the first time you send things from Vegas to DVDA.

For two channel I'd leave it as a PCM stream. There are two ways you can do this for PCM. The first is to render a separate audio file in Vegas. Look for wave file output in the rendering choices. I'd suggest you leave it at 48kHz but drop to 16-bit files to make it compatible with DVD players.

When you get to DVDA, check the menu location where you access the video. There wil be a line in the upper right of the screen that shows the file location of the video. Below that line should be the audio file location. Fill in your rendered audio wave file and you should be set.

The other way to do this is to go enable audio when rendering the video in Vegas. Go into the config file when rendering and look for the audio tab. That will mux the audio in with the video.

Andy

rs170a wrote on 6/13/2005, 6:49 PM

DVDA will convert whatever audio you feed it to AC3 (this is why it "recompresses") so you may as well have Vegas render that out for you to begin with.

For your video, select "DVD Architect NTSC video stream" in the MPEG-2 drop down menu. As long as it's under 1 hr. 10 min. (approx.), you'll be OK with the default template. If it's more than that, you'll need to get a bitrate calculator (I recommend BitCalc110 ) and figure out what your settings should be, either CBR or VBR. This is accessed by selecting "Custom - Video" next to the "Template" window.

For your audio, select "AC-3" as the file type. Do the following to get the best audio from your DVD:
Encode set to AC3;
Click on the Custom tab;
On the first tab, set diag. norm to "-31";
On the last tab marked preprocessing, set the Line mode profile
and RF mode profile modes to "none";
Now save that as a preset.
As long as you give both files the same name (eg. -"Live Band.mpg and LiveBand.ac3), DVDA will automatically find the audio when you select the video.
HTH.

Mike

wm_b wrote on 6/13/2005, 8:31 PM

Thanks Andy and Mike.

Mike,

Am I correct that the Diag. Norm to "-31" is setting the Audio Level to -31. I could master to that level before vegas or should I let Vegas do it. Is -31 the eqivalent to -0 in the digital audio world? I'm new to video so these generalities are still undiscovered for me.

Thanks again for the help, Wm.

Liam_Vegas wrote on 6/13/2005, 8:40 PM

DVDA will convert whatever audio you feed it to AC3 (this is why it "recompresses") so you may as well have Vegas render that out for you to begin with.

That's the default behavior of DVDA - but you can override the audio format either when you first create a new project in DVDA - or by modifying the project properties. There is a drop-down in the project properties in DVDA for the audio format.

Having said that... I pretty much always use .AC3 anyway.

wm_b wrote on 6/14/2005, 1:02 AM

Hey, It worked!! No Messages to Display. Cool.

Thanks , wm

rs170a wrote on 6/14/2005, 5:58 AM

Am I correct that the Diag. Norm to "-31" is setting the Audio Level to -31. I could master to that level before vegas or should I let Vegas do it.

From craftech's response to the Audio low after rendering post:

-------------------------------------------

From Dolby Labs:
"To prevent these apparent loudness differences from becoming bothersome when switching between programs—thus causing the listener to readjust the volume control—Dolby Digital has incorporated a "dialog normalization" feature to allow the producers to set the appropriate reproduction level to a known average level reference. This feature is implemented in Dolby Digital encoders and consumer decoders."

Since the quietest sounds amidst the grenade launchers and Jurrasic growls are the movie dialog, Dolby Labs have set the encoding standards to a dialog normalization level of -31db. The Dolby Digital encoder sends a control word called a dialnorm to the decoder to adjust playback level. It acts like an automatic volume control but only through attenuation (lowering). For full volume with no attenuation the dialog normalization value is -31db (in other words an "average" of -31db) which the dialnorm in the encoder leaves alone when it encodes AC-3. This allows the other levels in the program to be adjusted appropriately relative to the dialog, but striclty through attenuation. Thus the default setting of -27db is already telling the encoder that the average dialog is 4db higher than the -31db reference and as a result the dialnorm will reduce the levels across the board by 4 db. Set it to -20db and it will reduce it by 11db. That's why lowering the number will do the reverse of what one would think would happen at first glance.
So If you want to raise the overall volume of the encode set dialog norm to -31db.
You should also set the line mode profile under dynamic range control to none so that the dynamic range isn't compressed especially if there is music.

-------------------------------------------

And Spot added:
"Also, setting the Film Mode to none, and same with the LMP, you'll remove some of the decoder's control over your sound as well."

The Home Theatre HiFi site has a decent article on this as well.

Hope this helps to clarify things somewhat.

Mike

rs170a wrote on 6/14/2005, 5:59 AM

... you can override the audio format ...

Doh!! Thanks for the reminder Liam. I use AC3 exclusively so I completely forgot about that option.

Mike

StormMarc wrote on 6/14/2005, 1:57 PM

Thanks for the info on the Diag. Norm. But what should the vegas project audio be set to before going to AC-3? Will having it at 0 as opposed to -12 make a difference to the AC-3 encoder?

Thanks,

Marc

wobblyboy wrote on 6/15/2005, 12:36 AM

Vegas default is for Video Production. It uses film standard to deal with the wide audio dynamics involved in movie sound. If you are making a band video, you will want something closer to a CD and you may wish to set option to none, or music. You can render audio to wave and let DVDA re render. You can render to MPEG2 and let DVDA re render, or you can render audio to AC3 and seperatly render video to mpg. If you render to AC3 in Vegas, you have to actually place audio in DVDA project or use option to attach audio file to your video file. All you need to do to place audio in DVDA is place Video on menu, double click to open time line for that clip and add audio tracks by dragging them from explorer window, media window etc,. I often just render project to MPRG2 and let DVDA render sound. Sound renders so quickly that it will not significantly impact your render time in DVDA.