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Another Q for you audio experts - Stereo vs. Dolby Surround

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OK, I know that a "Dolby Stereo" soundtrack in the theater is exactly the same as "Dolby Surround" on LD or VHS. In the early days of Dolby Stereo there was some doubt about whether a matrixed sound format was compatible with mono equipment. Is this why some VHS releases (http://www.davisdvd.com/misc/ep4.htm) have Stereo (Mono Compatible) and some are Stereo Surround? Are the plain stereo soundtracks therefore recorded differently from the surround soundtracks, i.e. the surround channels simply added to the two main channels instead of being matrixed in with surround encoding?

I know that the UK VHS widescreen release in the early 90s had HiFi Stereo Sound - no mention of Dolby Surround - (this was the 1985 digitally remastered mix), but my 1995 release (features the THX remastered mix) actually has the Dolby Surround logo on the box.

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Mono compatible on VHS tape meant it had a mono linear track in addition to the stereo hi-fi track.

Anytime a matrix Dolby Stereo soundtrack was transferred to a stereo video format, the surround track was carried over, simply because of the way Dolby encoding works. Every stereo signal has an out-of-phase component, which is how Dolby Stereo was encoded.

Neil

Well at least the reversed surround channels have been addressed.

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Ah Neil, I knew I could rely on you to reply, thanks for the info.
Originally posted by: Neil S. Bulk
Anytime a matrix Dolby Stereo soundtrack was transferred to a stereo video format, the surround track was carried over, simply because of the way Dolby encoding works.
So how come some videos say HiFi stereo, and some say Dolby Surround?

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The HI Fi stereo vhs cases are more than likely older releases before the home cinema craze kicked off. Dolby Surround then became the buzz words to put on VHS boxes once Prologic Amps became common place.
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"So how come some videos say HiFi stereo, and some say Dolby Surround?"

Advertising, pure and simple. Terms are just being used interchangeably, just like different DVD companies use "Anamorphic", "Widescreen", "16x9" and "Enhanced for widescreen" to describe the same thing (and occasionally inaccurately.)

I love how many current DVDs refer to "menus" as a "feature" on the back of the case. It's not a feature...it's the standard. It's like saying "Buy our car, it's got TIRES!" LOL

<span class=“Italics”>MeBeJedi: Sadly, I believe the prequels are beyond repair.
<span class=“Bold”>JediRandy: They’re certainly beyond any repair you’re capable of making.</span></span>

<span class=“Italics”>MeBeJedi: You aren’t one of us.
<span class=“Bold”>Go-Mer-Tonic: I can’t say I find that very disappointing.</span></span>

<span class=“Italics”>JediRandy: I won’t suck as much as a fan edit.</span>

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I had a linear stereo VCR (With Dolby noise reduction) long before I had a hifi deck. The linear tracks on every stereo movie I had from that time were stereo. I'm guessing that a mono vcr or playback through the antenna outputs simply downmixed the sound? (Damned annoying that modern decks don't have linear stereo playback for older tapes.)
Some studios didn't want to pay extra for the use of the Dolby Surround logo, which is why a lot of older video titles simply say "Stereo Surround" even though the movie has a Dolby track.
I was puzzled back in the 80's as to why old four channel quadraphonic amps were flying out of local thirft stores until I learned some early home theater buffs were getting them to decode the surround tracks off of laserdiscs.

Originally posted by: Neil S. Bulk
Mono compatible on VHS tape meant it had a mono linear track in addition to the stereo hi-fi track.

Anytime a matrix Dolby Stereo soundtrack was transferred to a stereo video format, the surround track was carried over, simply because of the way Dolby encoding works. Every stereo signal has an out-of-phase component, which is how Dolby Stereo was encoded.

Neil


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Where were you in '77?

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Originally posted by: Moth3r
Ah Neil, I knew I could rely on you to reply, thanks for the info.
Originally posted by: Neil S. Bulk
Anytime a matrix Dolby Stereo soundtrack was transferred to a stereo video format, the surround track was carried over, simply because of the way Dolby encoding works.
So how come some videos say HiFi stereo, and some say Dolby Surround?

Hi-Fi- Stereo is actually a recording term for VHS tapes. Hi-Fi on the packaging means the tape has a Hi-Fi track. That was not the standard when VHS first came out. Dolby Surround logos were added later, but once the master was made, the Dolby encoded soundtrack always came through, whether the logo was on the packaging or not. I could bore you with the technical details of the Dolby matrix, but that's not necessary.

Neil

Well at least the reversed surround channels have been addressed.

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Originally posted by: MeBeJedi
I love how many current DVDs refer to "menus" as a "feature" on the back of the case. It's not a feature...it's the standard. It's like saying "Buy our car, it's got TIRES!" LOL
Well they are a feature really, I mean a car won't go without tires but a DVD will play without a menu. And they usually advertise "interactive chapter selection menus". Now I have seen commercial discs without interactive chapters selectable in the menus. There's nothing sadder.
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"but a DVD will play without a menu."

While this is technically true, I'd love to see you count how many DVDs you know of that DON'T have menus. (Personally, I can't think of any). A DVD without menus is the rare exception, not the norm. Your point is not incorrect, but it misses the reality of the situation: DVD manufacturers continue to list it alongside such things as director commentaries and deleted scenes, as if it's a real biggie, and it really isn't.

Now, if I recall, there was a DVD without chapter stops, but that was at the specific request of the director. I think it was a David Lynch film.

<span class=“Italics”>MeBeJedi: Sadly, I believe the prequels are beyond repair.
<span class=“Bold”>JediRandy: They’re certainly beyond any repair you’re capable of making.</span></span>

<span class=“Italics”>MeBeJedi: You aren’t one of us.
<span class=“Bold”>Go-Mer-Tonic: I can’t say I find that very disappointing.</span></span>

<span class=“Italics”>JediRandy: I won’t suck as much as a fan edit.</span>

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Recent low price Universal DVDs do not have menus. My Cloak & Dagger DVD is one of them.

Neil

Well at least the reversed surround channels have been addressed.

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Originally posted by: MeBeJedi

Now, if I recall, there was a DVD without chapter stops, but that was at the specific request of the director. I think it was a David Lynch film.


You are correct. Lynch DVDs without chapter selection include The Straight Story, Mulholland Dr and Eraserhead. It's his belief that a film should be taken in one sitting because it was not written to be segmented or to be set aside and come back to, like a book.

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Hi everybody. You’re all awesome. Keep up the good work.

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Originally posted by: Neil S. Bulk
Hi-Fi- Stereo is actually a recording term for VHS tapes. Hi-Fi on the packaging means the tape has a Hi-Fi track. That was not the standard when VHS first came out. Dolby Surround logos were added later, but once the master was made, the Dolby encoded soundtrack always came through, whether the logo was on the packaging or not. I could bore you with the technical details of the Dolby matrix, but that's not necessary.

Neil

your on it


Originally posted by: ReverendBeastly
Originally posted by: MeBeJedi

Now, if I recall, there was a DVD without chapter stops, but that was at the specific request of the director. I think it was a David Lynch film.


You are correct. Lynch DVDs without chapter selection include The Straight Story, Mulholland Dr and Eraserhead. It's his belief that a film should be taken in one sitting because it was not written to be segmented or to be set aside and come back to, like a book.


And I concur with Mr. Lynch on this... IMHO I find no need for Chapter Selection on DVD's; I've never really used this feature before and that is why the DVD's that I author don't have them.

“My skill are no longer as Mad as the once were” RiK

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Example: I have "Die Hard" on VHS from the early 90s, and the case says "HiFi stereo sound" - but since this was a Dolby mix in the theater, this will actually be Dolby Surround on the tape.

Is there any scientific way of finding out if an analogue stereo signal has Dolby Surround encoding? Apart from listening to it through a pro-logic decoder. I'm thinking more along the lines of TV broadcasts; if you feed any stereo signal into a pro-logic decoder you will get some steering to the rear channel, how can you tell the difference between something like The Simpsons which is broadcast in Dolby Surround or some other program which is plain stereo and any rear channel output you get is unintentional?

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Originally posted by: MeBeJedi
Now, if I recall, there was a DVD without chapter stops, but that was at the specific request of the director. I think it was a David Lynch film.
I'm not talking about 'till human voices wake us - I mean I've seen commercial discs (poor quality) that do have chapter stops, but no chapter selection menu.
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Originally posted by: Moth3r
Example: I have "Die Hard" on VHS from the early 90s, and the case says "HiFi stereo sound" - but since this was a Dolby mix in the theater, this will actually be Dolby Surround on the tape.

Is there any scientific way of finding out if an analogue stereo signal has Dolby Surround encoding? Apart from listening to it through a pro-logic decoder. I'm thinking more along the lines of TV broadcasts; if you feed any stereo signal into a pro-logic decoder you will get some steering to the rear channel, how can you tell the difference between something like The Simpsons which is broadcast in Dolby Surround or some other program which is plain stereo and any rear channel output you get is unintentional?


I think most of the dialogue on a prologic encoded stereo track goes to the centre channel. I once read somewhere that the only way to tell if it's a true prologic soundtrack is to disconnect front left and right speakers and listen for any bleed of dialogue from centre to rear if it's EXCESSIVE BLEED chances are it 's just a stereo track.
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"Recent low price Universal DVDs do not have menus. My Cloak & Dagger DVD is one of them."

That was a cool movie. Universal is dropping menus now? LOL! That's pretty damn cheap of them, considering it takes maybe twenty minutes to do. Are there chapter stops?

<span class=“Italics”>MeBeJedi: Sadly, I believe the prequels are beyond repair.
<span class=“Bold”>JediRandy: They’re certainly beyond any repair you’re capable of making.</span></span>

<span class=“Italics”>MeBeJedi: You aren’t one of us.
<span class=“Bold”>Go-Mer-Tonic: I can’t say I find that very disappointing.</span></span>

<span class=“Italics”>JediRandy: I won’t suck as much as a fan edit.</span>

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I'll make this realy really really really simple.

If it is a stereo tape, DVD, LD, broadcast....whatever and it was a movie mixed in Dolby Stereo, it will always be in Dolby Stereo, regardless if that little logo is on there. The way Dolby encoding works is it puts the surround information in the out-of-phase content of a stereo signal (L-R). Everything that is stereo has out-of-phase content. Play any stereo CD in Dolby Pro-Logic if you don't believe me. All Pro-Logic is active matrix decoding (as opposssed to passive decoding, just known as Dolby Surround). To get the center channel it sums the left and right channels (L+R). And that's it! So there is no need to worry over any of your stereo videotapes, or broadcasts, or DVDs or LDs.

And Pro-Logic is a decoding process, not an encoding process.

Neil

Well at least the reversed surround channels have been addressed.

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But pro-logic (unlike pro-logic II) is not intended to be used on a stereo source that was not surround-encoded. So if you can't rely on the presence or absence of a logo on the packaging, and it's not something like a regular movie that you can use IMDB to tell whether or not it was originally a Dolby stereo mix - how do you know?

Actually, let's use an example: "Walking With Dinosaurs" , the 1999 BBC TV series - the DVD packaging says Dolby Digital 2.0 stereo(despite there being a 5.1 trailer on the disc!), IMDB says stereo, and yes, the audio is in stereo. However if you turn pro-logic decoding on whilst listening to this, it sounds like the audio was deliberately encoded with surround information. And it sounds more to me than just unintentional out-of-phase like you would get when listening to a music CD with pro-logic turned on.

Now, what about the French soundtrack of the Star Wars laserdiscs? Well, according to the LDDb, "the sound of this LD is Stereo and not Dolby Surround because the original 1977 French mix for the movie was only a two-track Stereo mix, due to limitations of French theaters at the time". So if this is correct, and I was to sample and encode the French track for a DVD, it would be wrong to set the surround flag in the AC-3 stream. Is there any way to confirm this?

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Originally posted by: Moth3r
Now, what about the French soundtrack of the Star Wars laserdiscs? Well, according to the LDDb, "the sound of this LD is Stereo and not Dolby Surround because the original 1977 French mix for the movie was only a two-track Stereo mix, due to limitations of French theaters at the time". So if this is correct, and I was to sample and encode the French track for a DVD, it would be wrong to set the surround flag in the AC-3 stream. Is there any way to confirm this?

Listen to it.

And maybe I'm not being clear. All a Dolby Stereo track is is a stereo track with surround information encoded in the out of phase material. It will always be carried over. Always. It's impossible for it not o be there once it's mixed. I don't care if htere is a logo on the package or not. The info is there.

Neil

Well at least the reversed surround channels have been addressed.