Red,
The Dolby features are the encoding parameters (and have nothing to do with DTS, I think maybe you mean Dolby Digital or DD 5.1).
This is strictly a DD 5.1 encoder and does not create the stereo pcm surround encoded material. You need a separate encoder for this capability. Remember that ProLogic I surround encoding only gives you L,C,R,S while PLII will give you stereo surrounds. There are some nice parameters in the DD encoder that let you control the stereo downmix performed in 2 channel systems.
bgc


When you say there's Dolby features we must be only talking about DTS 5.1? I was trying to figure out a way to render to Dolby Pro Logic I or Pro Logic II. Is there not a way to do this with Vegas/DVD Architect/or the AC-3 utility?

Even when making a DVD that has 5.1 surround, there is always a downmix of the 5.1 into a Lt and Rt signal for us people who only have a stereo system. How can I get those Lt and Rt signals without having to burn to DVD?

Vegas has no 2-channel Dolby Surround encoder, but all Dvd-players have a builtin Dolby Digital Decoder than can downmix to two channels on the fly. If you still want to a make a Dolby Surround track you can downmix it with Azid. I use the BeSweet GUI together with Azid to make it simpler. It works pretty well. The downside of course is that you're encoding to lossy AC3 first and then to lossless wav. There are probably more free utilities out there that can downmix directly from six wavs, but I haven't looked.

By the way, you can't "make" a Pro-Logic or Pro-Logic II track. There is only Dolby Surround. The "Pro-Logic" refers to the more refined way to decode Dolby Surround encoded material. For example, a Pro-Logic decoder might compensate for misaligned tapeheads.

And another thing, maybe it should be clarified that not everything in the Dolby Surround Mixing Manual that SonicEPM linked to needs to be applied. Especially the part about Decoder Mistracking which doesn't apply to discrete Dolby Digital at all. Basically it tells you that if you have an ambient sound in the rears, you have to mute that sound briefly if you're adding another effect, say to the right, otherwise the decoder will be confused.

You could argue that it could still be a problem if you're downmixing to two channels, but why limit yourself and add all that extra work? Besides, decoder mistracking was more of a problem on regular surround decoders (non Pro-Logic), and who uses those today?

Good info Roger, just curious if there is such an animal as a software dolby surround encoder. Havn't had to use one yet, but if I get any TV commercials at my studio it would be a nice option. Thanks, Steve S

"The Dolby features are the encoding parameters (and have nothing to do with DTS, I think maybe you mean Dolby Digital or DD 5.1)."

Yes...that's what I meant to say. Sorry for the misunderstanding.

Roger_74 said:
"By the way, you can't "make" a Pro-Logic or Pro-Logic II track. There is only Dolby Surround. The "Pro-Logic" refers to the more refined way to decode Dolby Surround encoded material. For example, a Pro-Logic decoder might compensate for misaligned tapeheads."

I don't fully agree with this. Yes, Pro-logic is the term for the decoders, and for the decoders to work fully optimized the material must be "Encoded". The encoding process adds phase information to the track, that can then be decoded using the phase relationship between the Left and Right signals. Misalligned tape heads would cause phase problems between the Left and Right signals...so if anything the decoder would incorrectly steer the signals because the phase is not correct.

"You could argue that it could still be a problem if you're downmixing to two channels, but why limit yourself and add all that extra work? Besides, decoder mistracking was more of a problem on regular surround decoders (non Pro-Logic), and who uses those today?"

I use those today and about 300,000 vehicles that will be built this year that I've worked on the development of surround within an automobile. I work for Harman International in the OEM group and we developed "Logic 7" a "(non Pro-Logic)" decoder. ProLogic I was developed for movie surround which only had Left,Right, Center, and rear Surround channels. Pro Logic II was developed more for music surround and to compete with our Logic 7 decoder. We've done double blind tests between ProLogic II and Logic 7 decoders and found they are very similar, but Pro Logic II still is a little incorrect in it's steering for some surround encoded material.

The automobile and using surround decoders is a perfect solution to getting surround within an automobile. No one broadcasts FM in 5.1 yet do they? Even Satellite Radio, is only 2 channel information. Most CD's are 2 channel mixes....so how do you get surround in a vehicle? The answer is encode your mixes with either Dolby surround or Logic 7 encoders and play it back in a system that has a decoder. These encoded down mixes can then be broadcast in stereo and you can have surround on playback.

Most people who don't really understand or have never heard 2 channel encoded material played back on decoder system have the viewpoint that Logic 7 or Pro Logic I/II aren't really surround, but are simulated surround. I recently had a first hand experience with this very view point. I was in a 2004 Toyota Sienna Mini-van with an engineer from Toyota, Panasonic and Fujitsu Ten and that statement was made about our JBL "synthesis" surround..."That it's really a SIMULATED surround". I said, oh really? I pulled out my CD with a Logic 7 encoded circle pan of pink noise and played it back. Their jaws dropped to the floor as the pink noise circled around the vehicle. I then switched to some tracks, which had dolby encoded pink noise and individually turned on Left Front,Center,Right Front,Left side, Left Rear, Right Rear, and Right side. Then I put a DVD in the rear seat entertainment system installed in the vehicle, which played back the LT/RT signals and was decoded. Again, surround information was played back. I believe their whole viewpoint of "Simulated" surround was changed at that point. I believe their actual statement was "Wow!!!..that's awesome".

So what's your opinion on the question I raised in my post? Should we mute ambient sounds when a car door slams (like suggested in the .pdf example under Decoder Mistracking) to make it easy on "simpler" decoders?

I guess the ideal would be to make two mixes, but... yuck.


I'm thinking of making a script that would use Azid and other programs to downmix to 2-channel Dolby Surround directly from Vegas. The script could also be used to render to AC3 (2-channel Dolby Surround or 5.1) with freeware programs.

The only decoders I'm familiar with are Dolby Pro logic, Logic 7, and DTS Neo. Of those 3 obviously I'm most familiar with Logic 7. Even that knowledge is limited that I don't know the exact decoding equations and therefore couldn't tell you for certain if this will be a problem or not. That information is only shared between a few software engineers throughout the company and they've been instructed to be tight lipped because it's proprietary information.

I will need to download that surround guide and see what they are referring too. My initial reaction would be not to worry about muting anything. If a "simpler" decoder gets confused then that's the decoders problem. There's somewhere along the mixing line where you have to draw the line and say "I'm mixing so that it sounds good on most of the systems out there, but I can't feasibly make it sound good on every $50 surround system without compremising the audiophile/critical listeners quality."

I would guess the "simpler" decoders are based off of Dolby Pro Logic I, which was a 2x4 Matrix decoder, where the equations would look like this:

Left Out= (1)(Lin)
Right Out= (1)(Rin)
Center Out= (.7)(Lin) + (.7)(Rin)
Rear Surround Out= (.7)(Lin) + (-.7)(Rin)

These equation do not take in account "phase" information between the channels, except the obvious of 180 degree phase of the rear surround, which is a basic Left Minus Right to give you ambient information out the rear surround channel, which has it's own issues if the input signal is MONO and you get no surround channel.

I'ld definitely be interested in the script you're talking about. I will also be looking into Azid as you suggested also for Vegas. I've been using "Pan handler" previously in Vegas 3 to get the Dolby Encoding within Vegas. I was really hoping Vegas would have encorporated a Dolby Encoder if they're paying for licensing for Dolby. I do a lot of testing on our Logic 7 decoders and use Vegas on a laptop in the office, burn an audio CD and goto a listening room and then compare how that sounds in the vehicle also.