THX and Dolby Surround

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fluffy
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Post by fluffy »

Oh, so mp3 is out of the question, and we have to use an SACD mastering facility?
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Post by Hoblit »

fluffy wrote:Oh, so mp3 is out of the question, and we have to use an SACD mastering facility?
Absolutely.
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Post by fluffy »

Damn, my SACD export plugin is broken. How about DTS?
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Post by Hoblit »

fluffy wrote:Damn, my SACD export plugin is broken. How about DTS?
Dallas Theological Seminary?

sorry, had to look it up and I'm still not sure what DTS is...

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Post by fluffy »

DTS = Digital Theatre Surround. It's what a lot of movie soundtracks are based on. High-end 5.1 (or 7.1 in some flavors) CODEC which uses the same amount of bandwidth as an uncompressed CD audio stream (in DTS-equipped theatres they actually play it on a special CD player which is synchronized to the film via SMTPE timecodes, which is why it's lost ground to Dolby Digital which doesn't require as much fancy/finicky equipment).
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Post by fluffy »

Total non-sequitur on all three points.

DTS is a trademark which refers to a specific audio encoding, basically a brandname which also specifies an algorithm (like how MP3 means "this is an audio stream using the MPEG-1 audio layer 3 protocol"). For the home the only practical difference between DTS and Dolby Digital is the algorithm. Opensource software exists to let you play and encode Dolby Digital (AC-3) stuff just like an mp3 or whatever.

5.1 just means "5 positional channels, 1 nondirectional channel." Dolby Digital (AC-3), DTS, SDDS, Pro Logic II, and so on are all different ways of encoding 5.1 (AC-3 and DTS also provide 7.1 modes nowadays, though IMO it's just a gimmick, and really 4.1 is all you *really* need for a home setup).

DTS is the main competitor for Dolby Digital in both movie theatres and home theatres. Many DVDs these days provide both Dolby Digital and DTS tracks. The difference for the home listener is bascially nil.

THX is not a specific protocol or format, but a set of specifications which basically mean that a system will please the ears of George Lucas's acoustic research guy. It's a bit of a moving target, but it specifies everything from the number and position of the speakers down to the material the walls are made out of and their sound dampening characteristics.

Dolby Digital and DTS setups can both be THX-rated. Also, you can buy amps which are THX-certified but that doesn't mean that simply installing one will give you a THX-certified listening environment and so on, it just means that it's capable of providing enough power at the right frequency distribution to allow a setup to be THX-certified for a room of a certain size and so on.

If a movie theatre is THX-certified then they have the privilege of running that "The Audience is Now Deaf" trailer. THX takes their audio logo very seriously, and very aggressively protect it (and crack down on theatres which play that trailer without actual THX certification and so on).
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Post by Calfborg »

fluffy wrote:5.1 just means "5 positional channels, 1 nondirectional channel." Dolby Digital (AC-3), DTS, SDDS, Pro Logic II, and so on are all different ways of encoding 5.1 (AC-3 and DTS also provide 7.1 modes nowadays, though IMO it's just a gimmick, and really 4.1 is all you *really* need for a home setup).
I recently heard about a 9.1 setup. That's just overkill. I prefer 5.1 or 6.1 DTS. Plus, the little red DTS logo looks a lot cooler on my recevier than the Dolby Digital one.
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Post by fluffy »

What's worse is THX2 specifies 10.2. Yes, *two* subwoofer channels. Because, yeah, that nondirectional source needs to be in stereo. Muh.

Oh, and the 10 is two layers of 5s (one high, one low), which also makes no sense since the ear can't reasonably discriminate between sound sources at different heights (or positions, really) and so height is usually filled in by other cues, some auditory (which are already encoded into the normal 5-channel surround) but mostly visual (which the sound system has nothing to do with, obviously).

2 speakers is all you need for a single listener who doesn't move around much. 4 is useful for multi-listener environments, and 5 is marginally better. More than that is totally useless.
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