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Discussion Starter · #1 ·
Hope this is the right forum for this.


I have a very modest audio setup, but it's fine for what I want. I have a small receiver that has DD5.1 and DTS decoding, as well as ProLogic (version 1) decoding.


My question is, if I put a PLII audio source into the receiver, is it backwards compatible with my PL1 receiver? Does it properly decode the surround information (merging the L and R surrounds into the mono surround of PL1)? Or, is the PL1 not cabpable of properly decoding the sound and I should just run a stereo signal instead?


Ruahrc
 

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Pro Logic, Pro Logic II, Pro Logic IIX, and Pro Logic IIZ are decoding technologies. There is no such thing as "Pro Logic II content".


As far as Dolby content goes, there is Dolby Surround (a matrixed surround sound format that is decoded by any of the above decoder technologies), and Dolby Digital (both lossy and lossless).


You have no issues.
 

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Quote:
Originally Posted by Ruahrc /forum/post/18302155


My question is, if I put a PLII audio source into the receiver, is it backwards compatible with my PL1 receiver?

Yes. From the Dolby site : "Stereo audio encoded with Dolby Pro Logic II can be decoded by any form of Dolby Pro Logic."
 

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So posts 2 and 3 contradict each other. Is there such a thing as DPL II encoded material or not?


Ed
 

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Quote:
Originally Posted by ekb /forum/post/18307897


So posts 2 and 3 contradict each other. Is there such a thing as DPL II encoded material or not?


Ed

No there is not.


DPL 2 is a way of matrixing STEREO surround sound (using a centre and rear speakers) from regular old 2 channel stereo recordings. When the recording responds well to the Dolby PL2 decoder, it sounds like individual instruments have been assigned to the rear channels by the recording engineer--in other words EXCELLENT!!!



DPL does this by providing only frequency limited mono sound from the rear speakers. This, in my experience, never sounds better than mere ambience.
 

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Discussion Starter · #7 ·
Thanks for the confirmation.


It is my understanding that yes, there can be material specifically encoded for PLII. Also if it were merely an upmixing scheme, the word PLII decoding probably would not be used. Yes, PLII can be used to upmix any stereo source to provide "surround sound", but it is also possible to arrange your stereo signal such that you can deliberately control what plays from what speaker. If you think about it, as long a you know what PLII is going to do to the stereo signal, you can be smart about feeding your stereo signal to a PLII decoder to give you a desired surround output.


Game consoles like the PS2 and Gamecube use PLII in order to provide surround sound without using a dolby digital 5.1 encoder chip (like the xbox, 360, etc do) or a digital audio connection.


The reason behind the original question was that I have been copying and encoding my DVDs into h.264 for playback convenience. In the encoder program I am using there is an option to downmix the 5.1 audio tracks into stereo, dolby surround, PLII, or discrete channels. I include the digital AC3 track because my decoder handles 5.1 too, but I wanted to include an analog track for wider playback compatibility. I was not sure whether or not encoding into PLII would provide inferior results using my PLI decoder vs. encoding in dolby surround mode.


Ruahrc
 

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No, Dolby Pro Logic 2, like Pro Logic, is ONLY a circuit that takes 2 channel ANALOG sound and matrixes it into 5 or 5.1 channels. There is no such thing as a specific Dolby Pro Logic 2 Mix.


If a broadcast, TV or radio, starts out as Dolby Digital (5.1 or 2.0) mix it is simply mixed down to stereo at the source for those with SD TV or analog audio reception. The Dolby Pro Logic 2 circuitry can then matrix a 5 or 5.1 channel mix back out of the 2 channel signal. The Dolby Digital 5.1 mix is kept in the digital domain for its part of the broadcast and you need a Dolby Digital decoder in your AVR or TV to decode it.


DPL2 Movie, Music and Game are just slightly different ways of matrixing the original stereo signal up to 5 or 5.1.
 

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Quote:
Originally Posted by bluesky636 /forum/post/18302346


Pro Logic, Pro Logic II, Pro Logic IIX, and Pro Logic IIZ are decoding technologies.

Correct.
Quote:
Originally Posted by bluesky636 /forum/post/18302346


There is no such thing as "Pro Logic II content".
Quote:
Originally Posted by Sitting Bull /forum/post/18308434


No there is not.

There is no such thing as a specific Dolby Pro Logic 2 Mix.

Incorrect, as the other posters have amply illustrated.

Quote:
Originally Posted by Sitting Bull /forum/post/18311976


No, Dolby Pro Logic 2, like Pro Logic, is ONLY a circuit that takes 2 channel ANALOG sound and matrixes it into 5 or 5.1 channels.

Well, while the original incarnations of Pro Logic were indeed analog circuits, all current PL and PLII circuits are digital. Analog sources must be converted to PCM in order to be processed.
 

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Quote:
Originally Posted by Roger Dressler /forum/post/18314666


Correct.


Incorrect, as the other posters have amply illustrated.


Well, while the original incarnations of Pro Logic were indeed analog circuits, all current PL and PLII circuits are digital. Analog sources must be converted to PCM in order to be processed.

Hi Roger,


I went back to look over the articles cited by others in this thread and the best I can make out is that the broadcaster produces a Dolby Digital 5.1 mix at the source and mixes it down to stereo for broadcast to those who have only mono, stereo or Dolby Pro Logic and PL 2 decoders.


From what you are saying, but not explaining, I can only assume that Dolby has designed a set standard for folding the DD 5.1 original into a stereo mix that a Dolby Pro Logic 2 decoder can matrix back into 5.1 in a fairly faithful reproduction of what was intended.


My best understanding of Dolby PL 2 decoding is that it relies on spatial and timing cues in the original stereo mix to conjure up its surround sound mix. A few of my regular old CDs respond very well to the Dolby Pro Logic 2 decoder, but most only produce ambience. Some that do sound good are the first three or four Ottmar Liebert flamenco CDs, and also the PCM stereo track of the 1996 Doobie Brothers live New York City concert DVD called "Rockin' Down the Highway."


I have never seen any CD for sale that boasted a Dolby Pro Logic 2 5.0 or 5.1 mix. If Dolby has indeed developed a set standard for producing convincing 5.1 CDs utilizing Pro Logic 2, I don't understand why they don't have all the studios producing their stereo CD recordings for these Dolby PL 2 decodings. What a boon that would be for all of their customers with decent surround sound systems (which must be a substantial percentage by now), and it wouldn't cost anything more as long as the mastering was done according to such a standard.


Think about it. Almost every AVR produced for the last decade has a Dolby Digital and Pro Logic 2 decoder built right into it. It would almost wipe dts and their surround CDs off the map due to the ubiquitousness (ubiquity?) of Dolby's circuitry and dominance of the industry. And it could all be done from a simple CD player, not being dependent upon a DVD player and its onboard Dolby and dts decoders for playback.


I own one CD that claims to have been produced specifically for "Dolby Surround" reproduction, which as you know preceded even Pro Logic. It is a 1997 Silva Treasury CD of movie themes called "Westerns." I have only listened to it via a simple Dolby Pro Logic decoder on my old 1997 Pioneer Elite VSX-05 AVR and it is nothing remarkable at all, mere ambience, but that is all I have ever heard from any Pro Logic only decoder, (other than pure mono audience noise being furnished to the rear speakers on TV shows). Virtually worthless, in my humble opinion. I shall have to re-listen to it on my current Onkyo HT-RC 180 AVR with Dolby PL 2 decoding and see if that improves on my former experience.


My understanding of current DD and PL 2 decoders is that they are indeed digital now and all of the decoding is done in a single chip.


If you have something to add to what I have written here, please feel free to elaborate on it. We would all enjoy finding out what it is. This forum is for learning and we are all ears, so to speak.



Thanks!


Todd Sauve

(aka Sitting Bull)
 

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Quote:
Originally Posted by Sitting Bull /forum/post/18319947


I went back to look over the articles cited by others in this thread and the best I can make out is that the broadcaster produces a Dolby Digital 5.1 mix at the source and mixes it down to stereo for broadcast to those who have only mono, stereo or Dolby Pro Logic and PL 2 decoders.


From what you are saying, but not explaining, I can only assume that Dolby has designed a set standard for folding the DD 5.1 original into a stereo mix that a Dolby Pro Logic 2 decoder can matrix back into 5.1 in a fairly faithful reproduction of what was intended.

Analog (stereo) output can and was encoded specifically for DPLII decoding, to create a pseudo 5.1 output. The first example I saw was the videogame "Rogue Leader" on the Nintendo Gamecube.

Dolby discusses this on their website
Quote:
Game developers can take advantage of Dolby Pro Logic II to deliver thrilling surround sound with games for the Sony® PlayStation 2 and Nintendo® Wii. Cut scenes and music can be mixed specifically for surround playback, while spot effects can be encoded with coordinates that the game console can use to place the effects anywhere around the player in real time.
 

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That is great to hear, but if this is the case why has Dolby not persuaded the major studios to use it for their music CDs, and passed the benefits on to everyone with a CD player and relatively up-to-date AVR?
 

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Quote:
Originally Posted by Sitting Bull /forum/post/18319947


From what you are saying, but not explaining, I can only assume that Dolby has designed a set standard for folding the DD 5.1 original into a stereo mix that a Dolby Pro Logic 2 decoder can matrix back into 5.1 in a fairly faithful reproduction of what was intended.

An explanation of mixing for PLII can be found here . For the 2-channel downmix to decode more faithfully to the 5.1 original, it helps to use a PLII encoder during downmixing, like a hardware version from Dolby or a software plug-in from Minnetonka .
Quote:
Originally Posted by Sitting Bull /forum/post/18320157


That is great to hear, but if this is the case why has Dolby not persuaded the major studios to use it for their music CDs, and passed the benefits on to everyone with a CD player and relatively up-to-date AVR?

From its history, Dolby seems more interested in providing tools for content creators rather than being in an advocacy position promoting surround sound on CDs. Almost all music is mixed for 2 channels, so PLII encoding would be pointless since 5.1 originals are relatively rare.
 

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OK, great news. But I'm truly disappointed that Dolby PL 2 encoding has not been adopted by the music recording industry. It is a relatively small expense that would pay off in spades for their customers--US!


Any ideas folks?


Or are there actually Dolby PL 2 CDs available to be purchased somewhere?
 

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Quote:
Originally Posted by sdurani /forum/post/18320464


From its history, Dolby seems more interested in providing tools for content creators rather than being in an advocacy position promoting surround sound on CDs. Almost all music is mixed for 2 channels, so PLII encoding would be pointless since 5.1 originals are relatively rare.

Yes, but that is my point. If Dolby has sorted out how all the spatial and timing cues effect a surround mix, why not make the info available industry wide so we can all enjoy it as an added benefit to stereo mixes? An original 5.1 mix would not be necessary at all, would it?


Truly, if there was ever a time when multichannel surround sound could take off it is now, what with all the Pro Logic 2 capable AVRs on the market for the last decade.
 

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Quote:
Originally Posted by Sitting Bull /forum/post/18320548


An original 5.1 mix would not be necessary at all, would it?

I guess you didn't read the PLII mixing guide I linked to, otherwise you wouldn't be asking the above question. PLII encoding is simply a method of downmixing 5.1 content to 2 channels (albeit in such a way as to take full advantage of PLII decoding during playback). If you're not starting with a multi-channel original, then what are you downmixing?
 

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Quote:
Originally Posted by sdurani /forum/post/18320620


I guess you didn't read the PLII mixing guide I linked to, otherwise you wouldn't be asking the above question. PLII encoding is simply a method of downmixing 5.1 content to 2 channels (albeit in such a way as to take full advantage of PLII decoding during playback). If you're not starting with a multi-channel original, then what are you downmixing?

OK, I follow your logic. But some stereo CDs respond very well to PL 2 decoding. I can only assume that Dolby figured this out when designing the PL 2 decoder.


So, is it some sort of big problem to reverse engineer, as it were, what makes those simple two channel stereo recordings respond so agreeably to its PL 2 decoder? It seems to me that the research Dolby already has in the tank regarding this would be simple enough to codify for studios to apply when making their two channel mixes. Since they are already doing this for game mixes, or so it seems, (unless they are working from a 5.1 discreet digital original), why don't they make the info available for straightforward music stereo mixes from the original multi track recordings?
 

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Interesting. I learn something new here once again. Question: does anyone know whether many/any Blu-ray players use PLII encoding when downmixing for two channel output? Most manuals do not specify what kind of Surround Encoding is used and I always assumed it was Dolby Surround.
 

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Quote:
Originally Posted by sdurani /forum/post/18320620


I guess you didn't read the PLII mixing guide I linked to, otherwise you wouldn't be asking the above question. PLII encoding is simply a method of downmixing 5.1 content to 2 channels (albeit in such a way as to take full advantage of PLII decoding during playback). If you're not starting with a multi-channel original, then what are you downmixing?

Easy. Just take the 16 channel master (or however many channels the master is), and instead of mixing it down to 2 channels, mix it down to 6 channels. Then take that 6 channel recording and run it through the PLII encoder. I am assuming all content is PCM and mixed in the digital domain until the encoder spits out an analog signal, right?
 
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