Stereo AC3 Levels versus MPEG2

ChipGallo wrote on 5/16/2011, 6:27 AM

After preparing video in Vegas 10 Pro, I rendered MPEG2 files using the DVD Architect template. In DVDA the audio portion was marked as requiring render (little yellow !). I went back to Vegas and rendered these as stereo AC3 using the AC3 template. Back in DVDA the levels (visible on the timeline) were much lower than when the audio had been in MPEG2 format.

Listening to the final DVD, sound output seemed fine and didn't require abnormal amplification. Wondering why the audio track was so much lower in height with quieter areas being a straight line.

Comments

musicvid10 wrote on 5/16/2011, 8:14 AM

Depending on whether you used the Studio or Pro AC3 template, it is one of two problems.

a) The AC3 Studio template has a documented bug that causes (among other things) a levels bias in the DVD Architect preview.
It is also noncompliant with Bluray. Don't use it.

b) The default template in the AC3 Pro template has some Dialnorm and DRC settings that are not WYHIWYG. Assuming your audio is leveled correctly in the render, follow these settings exactly and the audio output will be fine.
"I've run some exhaustive tests with calibration test tones and done extensive reading of the Dolby metadata specs, and in reference to your question about the most accurate reproduction with the AC-3 Pro Encoder, I am prepared to make the following recommendations with notes:

ChipGallo wrote on 5/16/2011, 8:27 AM

Thanks Musicvid, I'll try this on the next project.

Tim48 wrote on 2/1/2014, 1:53 PM

Excellent advice, thanks! I was having trouble with the 5.1 audio and forgot how to fix it. This worked perfectly.

musicvid10 wrote on 2/1/2014, 3:31 PM

We aim to please ;?)