[vorbis] Multichannel files

[Mercier, Dave]

The DTS or DD "transcoding" feature of a PS2 player would of course have to
be licensed. This fee would be included in the PS2 player software you are
buying. This software has to be commercial anyway so I don't see a big deal
here. This is the absolutely only way to say get a PS2 to transport a 5.1
signal to your 5.1 receiver. To the user who bought the software, they would
only see something like "OggEnc" or "OggDrop" as their way of getting 5.1
audio on to a CD for the PS2 player to play. And that software is freely
available without patent issues. So to me there is a use for 5.1 Oggs (how
else would you get highly compressed 5.1 files on to a CD from any 5.1
source material you had, without any patent issues?).

Anyway, regardless of the PS2, without transcoding to a common 5.1 format a
receiver can understand, you are stuck with a mess of 6 analog cables to
sort out, and the possible noise interference they bring with them. I've got
a pretty wicked 5.1 setup, and some of my analog sources get a lot of
interference because of how long my cables are, etc., so I'd rather go
digital.

As well, pretty much all but the cheaper AV receivers have 5.1 analog
inputs. I've had 3 and they all have them.

Thanks,
Dave.

-----Original Message-----
From: Wilson [mailto:defiler at null.net]
Sent: Wednesday, November 14, 2001 1:06 PM
To: vorbis at xiph.org
Subject: Re: [vorbis] Multichannel files

There are two ways to decode multi-channel audio. In hardware, or in
software.
Hardware: A receiver or processor takes a Dolby Digital (for example) stream
and converts it into something your amps/speakers are interested in.
Software: Your PC decodes a 5.1 audio stream into six discrete audio streams
and passes them to analog output.

Sound cards that can handle what is described in the second case are fairly
rare. The Hercules Game Theatre XP, the M-Audio Delta Theatre ($$$), etc.
Most people don't have them. Doing real 5.1 output from the PC without a
receiver that locks you into Dolby Digital is either expensive (full pre/pro
combo) or rare (analog 5.1 multimedia speakers with LFE management. Hard to
come by.)
To play a multi-channel Ogg file through a receiver, the receiver would have
to directly support Ogg, and the sound card drivers would have to support
pushing the Ogg through Toslink or S/PDIF. An alternative is to transcode
the Ogg output on the fly into AC-3 for transport, but then we're not
patent-free anymore.

Either there's something I'm missing, or I don't see much of a use for 5.1
Oggs.

"In the grim future of Hello Kitty there is only war..."
http://supremetyrant.com/HK40K.jpg

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