Audio Render Questions: Render a balanced AC3 2.0 from 5.1 source

[Bryan Daugherty]

In the past yr and half I have gotten pretty good at recording and setting up 5.1 surround for my DVDs, but it has meant sacrificing the stereo output. For my 5.1 projects, I always add a 2.0 track and a menu on the dvd for the client to choose which best fits their system. I just am not happy with the dynamic range of the 2.0 track rendered off the 5.1 project. I have gone back to using the AC-3 studio presets instead of the pro as I found the pro renders to be somewhat lacking for 5.1 and 2.0. Who else is rendering 5.1 and 2.0 sound from a 5.1 project and getting good results? What do you recommend?

Thanks!

[Edward Troxel]

I would bet the pro one would work fine for you but you'd need to go in and change some settings. Most people complain that the volume gets too "soft" when using the AC3 renderer. This is technically supposed to happen but can be changed. To prevent the volume from dropping, make these changes:

Encode set to AC3;
Click on 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 mode to "none";
Save this as a preset.

[Bryan Daugherty]

Thanks Ed,
That is exactly the issue I have with the pro encoder. I balance and normalize my audio in edit and I like the output file to match my edit version. With the pro encoder I find it makes massive changes to my audio. It makes it way to soft and a lot of subtle audio seems to be completely lost. I am currently working on a recital project with 2 acts for 3 nights and 3 acts for 1 night (in other words 9 masters of MPG-2 and 18 AC3 masters) and I would really like the audio on this one to pop. The 5.1 sounds great but the stereo render is only pulling from the left and right front buses. I don't want clients to have to turn their receiver/TV way up while watching my DVDs it just doesn't make sense to me that the Studio outputs my edit and the Pro outputs a supremely inferior version. Though I often assume in such circumstances it is operator error...

Is there some way to get it to downmix from all buses? Of course a lot of the LFE is going to be lost because stereo doesn't support that option but there should be some way to make the LF and LR merge and the RF and RR merge and the center be balanced across both L and R. Am I looking for something that isn't possible?

Thanks!

[Bryan Daugherty]

Hey Ed (and anyone else interested) I tried something new on my recent edit. It is convoluted but seems to get me the stereo track I have been trying to achieve in the past. I edit my project in 5.1 panning audio where I want and balancing exclusively for the 5.1 surround mix and render the mpg and 5.1 AC3 file.

In DVD Arch (ver 5.2), I create a 5.1 project for DVD and prepare the folder. No menus and nothing flashy as this is a throw-away project in the end. When finished, I prepare the disc to a folder. Then I return to Vegas (Pro 10d) and create a new blank stereo project and use the Import->extract from camcorder disc and select the folder I prepared in DVDA.

This gives me a nice almost ready, stereo mix of the DVD with two issues. Anything that exists only on the rear or center channels is soft and the visible wave form is not everything going into the mix so the audio meters will peak without some tinkering. I split the tracks to isolate anything that is soft and normalize those parts (right-click under properties) and then drop the output fader on the master audio track on the meter to prevent any peaking (usually about 6-12db attenuation.) Render out to AC3 stereo and add to the real DVDA project as track2 audio (alternate audio.)

The end result is a really nice stereo mixdown of the 5.1 composite. This workflow is extremely convoluted but so far the end result is worth the effort. I am sure there is probably a more efficient methodology to get similar results but the only other thing I found that gets close is remastering the entire project manually which takes days instead of the 30-90 minutes the above workflow takes.

Let me know what you think...