Vegas+DVD AC-3 Works But Then Doesn't? Workflow?

DVD wrote on 4/17/2003, 4:43 PM

I've gone through the entire forum and the internet to figure this workflow issue out.

I have followed all the recommendations of Sonic Foundry, for example:

What I do?
a. For archiving to VHS to DVD, I use Dazzle Hollywood DV-Bridge and capture using Vegas 4.0+DVD, no lost frames, perfect capture (in AVI about 16GB for 1hr 6 min)
b. I render as (mpeg2 main concept) NTSC but with Audio unchecked
c. I render as (ac3 5.1 surround)
d. I open DVD Architect (latest version) build the menus, chapters, etc., and dynamic menu buttons (no problem at all)
e. I prepare the DVD and do the optimize and green check marks on the mpeg2 and yellow marks on the menus - no problem at all.
f. I preview the DVD and sound comes out my Dolby Digital Audigy Card via Center/Right/Left Surround/Right Surround/Subwoofer. No problem here.
g. I build the DVD and end up with vobs and then burn it.
h. I place the DVD into my Dolby Digital 5.1 Home Theater and NOW THE PROBLEM.
I own 4 different DVD players (top of the line, Pioneer, Samsung, Cyberhome, RCA)
and the DVD filling 3.9GBs of space @ 7,100 bits ONLY PLAYS IN STEREO, no sounds whatsoever from the other speakers. It sounds great and even each DVD Player changes automatically indicated Dolby Digital 5.1, even saw 48KHz, 6-channel on the screen pushing the audio indicator button on the TV. I DO GET SUBWOOFER SOUNDS!
i. I've tried the other way too starting with (a) above by just bringing in the AVI's into the Video/Audio of DVD Architect and rendering from DVDA into Dolby Digital 5.1 (EXACT SAME RESULT) - STEREO ONLY (Sounds nice) but Zip sound from any speaker except left and right. Light hissing from the Center Channel, no hissing from rear surrounds. I've also tried mpeg2 (no audio) with wav import for DVDA audio. SAME RESULT AGAIN and I DO GET SUBWOOFER LFE EFFECTS!
j. Now what is REALLY WEIRD is I do the exact same steps with some CD audio wave files and WOW! IT WORKS! I get Dolby Digital 5.1 out of all 5 speakers.

What's up?

PLEASE EXPLAIN EXACTLY WHAT I MUST DO OR SEND ME A SCRIPT TO DO THIS.
GETTING VERY FRUSTRATED AND HAVE BURNED 9 COASTERS.
PLEASE ADVISE - SPECIFICALLY - NO SHORT ANSWERS.

I am using Athlon 1800+ w/1GB DDR RAM, 300GB 7200RPM Harddrive, WinXP Professional
and HP DVD200i drive, Audigy Platinum sound card and also own DVD Movie Factory 2, Pinnacle Studio 8 Deluxe, DVD Complete, MovieStar5.

What's Up?

VR
Eddy

Comments

Cold wrote on 4/18/2003, 1:34 PM

First off, audio on vhs tapes is 2 channel. It may be in dolby surround, but dolby surround works by encoding the sound to two tracks, which is what is recorded on your vhs tapes, then a dolby decoder (surround, prologic) normally built into your amplifier will decode and break this back into surround. Its actually a little more complicated than this but the theory is sound.

So, if you take this 2 channel vhs audio, even if it is encoded in dolby suround,and render it into an ac3 file, the encoder will only see the two channels, which by default are panned across the front 2 speakers by the track panner, and encode a file with sound in the left and right speakers but dead air everywhere else (center,lfe,surr). Now when you burn this to a dvd and play it back through an ac3(dolby digital) decoder, you end up with exactly what you rendered in the first place, left and right only. The lfe you are hearing is not from the encoded source of the dvd but because most ac3 decoders have bass management functions that route the low end from the left and right speakers to the sub.

OK and now the solution, create your vhs backup dvds (the dolby surround vhs tapes anyways) using a wave file on the dvd of the recorded audio from the movie. In other words DO NOT reprocess the audio in any way from your original recording. This audio has dolby surround information already encoded into it. When you play the dvd your amp should show PCM on its screen and if you set your amp to dolby pro logic voila, surround just like the original vhs tape.

This is what is happening when you burn the audio from the vhs tape to a cd, the amplifier is simply decoding the already embedded dolby surround.

So to sum up, there is no value in rendering vhs dolby surround audio to ac3. In fact this will kill the encoded surround (you cannot decode dolby digital and prologic at the same time, amps are designed to decode one or the other at a time)

Hope this helps
Steve S
If this is unclear post back again. I look at this forum once a day or so.

cosmo wrote on 4/18/2003, 2:43 PM

that was quite a good answer. i was going to ask why the need for 5.1 from a vhs master? to make the DD light go on? -)

as a side note, I did the same thing with an avi music video for someone last week. However, I imported the audio file and duped it a few times and placed each copy in one of the six channels discretely. a little eq on the rears and center and some patience during mixing and shazaam, it really didn't turn out too bad. i put the 2.0 mix on a test dvd along with the 5.1 mix and the 5.1 mix blew away the 2.0 mix.(nice how dvd-a lets you change audio sources for a vid file...)

point being - if you reeeeaaaly want to turn a 2.0/4.0 mix into 5.1 and don't have discrete source files to work with, you can split it up and remix it. sounds like the dumbest thing in the world that you'd never want to do but surprisingly enough, the end result was good.

Sunray wrote on 4/18/2003, 2:51 PM

"you cannot decode dolby digital and prologic at the same time"

Actually, I believe that's not quite correct. There's an AC-3 encoder setting which should indicate to the decoder that Dolby ProLogic material exists in a stereo AC3 program. It's on the Bitstream tab, the option "Dolby surround mode". Set it to "Dolby surround encoded" if you've got prologic source material. I haven't tried this directly myself...I'll see if someone else here has attempted this...

-pj

Cold wrote on 4/18/2003, 3:17 PM

I stand corrected. Serves me right for giving such a long post. By the way Cosmo, I have done the same thing from time to time with varying results, but I asummed (perhaps incorectly) that the original post was about vhs tapes already encoded in dolby surround, just trying to make his life easier.
Steve S

dvddude wrote on 4/21/2003, 1:43 PM

I would be very interested to know if people have good luck with this. I myself was wondering if there wasn't some way of "peeling off" the surround 'channel' on capture. You know, kind of capture 2-channel pro-logic and have it appear in Vegas as three tracks (stereo plus surround) so that the "old" pro-logic surround track can be fiddled with and used as the rears in a 5.1 mix.

But if that encoder setting works, it's the next best thing. At least the amplifier will see the surround material and put it where it's supposed to be!