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#10421 - 08/28/02 07:13 AM DD and DD2
pegasus Offline
Gunslinger

Registered: 08/25/02
Posts: 52
Loc: Ky
Could someone explain the difference between Dolby Digital and Dolby Digital 2

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#10422 - 08/28/02 08:13 AM Re: DD and DD2
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
I think you mean Dolby Pro Logic and Pro Logic II. Both Pro Logic and Pro Logic II are designed to use a stereo signal (left and right channels only) to produce some form of surround sound (adding a center and surround speaker channels).

Pro Logic is the old surround processing that was based on a stereo analog signal into which a center channel and a surround channel (mono, with both left and right surrounds getting the same signal) were "matrixed" so that a Pro Logic decoder could extract them. When given a true stereo signal (i.e. a signal that was not originally intended for Pro Logic decoding), the Pro Logic decoders often had a hard time getting much out of the signal -- it would sometimes collapse entirely to the center channel, for example.

Pro Logic II is a new form of decoding intended to work with a stereo signal. It can still handle Pro Logic soundtracks, but it can also work well with purely stereo soundtracks. In many cases, Pro Logic II decoders include two modes -- one for movies, and one for music. Also, unlike the original Pro Logic, PLII produces a 5.1 channel output (discrete left and right surrounds and a subwoofer channel) and a full-range signal to all five channels (Pro Logic's surround signals did not cover the full 20Hz-20,000Hz frequency range, and I don't remember if the center did). Basically, Pro Logic II gets closer to the sound of Dolby Digital soundtracks than Pro Logic did. You might be interested in this link to Dolby's site .

Dolby Digital, by the way, is very different from these two. It is a digital format, with five discrete full-range channels (left, right, center, left surround, and right surround) and a ".1" low frequency effects ("LFE") channel. There is an extension of Dolby Digital called Dolby Digital EX that adds a surround back channel (one or two speakers at the back of the room) that is matrixed into the surrounds, much the way the Pro Logic matrixed in the center and surround channels.

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#10423 - 08/28/02 08:35 PM Re: DD and DD2
davewb Offline
Gunslinger

Registered: 06/18/02
Posts: 32
Loc: columbia, md, usa
an EXCELLENT response, gonk! a very clear explanation.

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#10424 - 08/29/02 10:57 AM Re: DD and DD2
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
The Gonkster never fails to come through.

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Matthew J. Hill
matt@idsi.net
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Matthew J. Hill
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#10425 - 08/29/02 12:55 PM Re: DD and DD2
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
I'm pretty sure DD is also out there in a 2.0 format, basically the audio is stereo/DPL but the data stream is encoded with the AC-3 algorithm.

I think. Right?
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Charlie

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#10426 - 08/29/02 01:23 PM Re: DD and DD2
Oaf Offline
Gunslinger

Registered: 06/19/02
Posts: 90
Loc: Vancouver,British Columbia, Ca...
Yup, 2.0 refers to Right and Left tracks only (stereo) but is encoded in the AC3/DD signal format. You see that as well as DD Mono often with older movies where they have been unwilling or unable to re-master the audio tracks.

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#10427 - 08/29/02 01:34 PM Re: DD and DD2
gonk Offline
Desperado

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
Dolby Digital can, I believe, include any number of tracks less than or equal to 5.1 -- so you can have Dolby 2.0 tracks (stereo, left and right channels only), Dolby 1.0 (mono), Dolby 4.0 (left, right, center, and mono surround), Dolby 5.0 (all channels but no LFE channel), or whatever.

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#10428 - 08/29/02 03:57 PM Re: DD and DD2
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
This is true, I think, except that it always has two tracks. Mono is encoded as two identical tracks.

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Matthew J. Hill
matt@idsi.net
_________________________
Matthew J. Hill
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#10429 - 08/30/02 12:42 AM Re: DD and DD2
Owl's_Warder Offline
Desperado

Registered: 06/29/01
Posts: 894
Loc: Grants Pass, OR
Quote:
Originally posted by Matthew Hill:
This is true, I think, except that it always has two tracks. Mono is encoded as two identical tracks.



Really? Any idea the reason behind that? Are they both decoded and played simultaneously through the center channel? Any insight how that works?

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#10430 - 08/30/02 02:00 AM Re: DD and DD2
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
I'll have to look, but I just picked up a bunch of Eastwoods Italian/Westerns (GB&U,Fistful, etc) and they are mono, center only. Thought they were DD.....

Charlie
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#10431 - 08/30/02 08:53 PM Re: DD and DD2
Owl's_Warder Offline
Desperado

Registered: 06/29/01
Posts: 894
Loc: Grants Pass, OR
Cool. Let us know if you find anything out. I suppose I could always investigate myself, but right now I'm just too darn lazy.

Nice choice on some flicks there. My wife got me the spaghetti western box set for christmas year before last. Great fun! I also introduced her to Outlaw Josie Wales which she had never heard of. She loved it!

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#10432 - 09/12/02 10:10 AM Re: DD and DD2
surroundophile Offline
Gunslinger

Registered: 05/02/02
Posts: 68
Loc: Chicago, Il. USA
Mono DD tracks are available both in DD1.0 and DD2.0. DD2.0 is just like on a normal (PCM)(CD, VHS, Laser, DVD) release, the two channels are identical.
There is also the option of DD3.0 (L-C-R only). One of my Marilyn Monroe DVDs has that.

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