[vorbis] Multichannel files

Thu Nov 15 05:21:22 PST 2001

----- Original Message -----
From: "Mark Hetherington" <mark.hetherington at studentmail.newcastle.edu.au>
To: <vorbis at xiph.org>
Sent: Wednesday, November 14, 2001 4:21 PM
Subject: Re: [vorbis] Multichannel files

> I think that surround would be great.
>
> Now I'm pretty sure the sound card+ drivers should be encoding the
surround
> signal into one usable by the spaekers, so it shouldn't be a patent issue
for
> ogg. In the same way as you do surround in a game, you should be able to
> position the audio streams when outputting them, without having to support
> AC-3 or anything other than the standard sound interfaces.
>
> I don't really know the technical aspects of writing software to output in
> surround but I know there are some Alsa layers doing surround.
>

My point is that a 5.1 speaker setup (even on a PC) that doesn't go through
a Dolby Digital decoder before hitting the speakers is a rare thing indeed,
and requires that you have a fairly specific breed of sound card.

They accused us of suppressing freedom of expression.
This was a lie and we could not let them publish it.
-- Nelba Blandon, Nicaraguan Interior Ministry Director of Censorship

>
> On Thu, 15 Nov 2001 08:05, you wrote:
> > 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
> >
> >
> > ----- Original Message -----
> > From: "Mercier, Dave" <dmercier at ea.com>
> > To: <vorbis at xiph.org>
> > Sent: Wednesday, November 14, 2001 3:56 PM
> > Subject: RE: [vorbis] Multichannel files
> >
> > > I think multi-channel is one area where Ogg could really find a niche
for
> > > itself. The reasons:
> > >
> > > 1) 5.1 Music is becoming more popular. There are DTS 5.1 audio discs
in
> >
> > use
> >
> > > now. There isn't really a way to stick these into a convenient
playback
> >
> > form
> >
> > > that I'm aware of though.
> > >
> > > 2) I'm not aware of a widely available MP3 encoder that supports a 5.1
> > > configuration. There are extensions to the MP3 format that allow 5.1,
but
> > > I've never seen them used anywhere for the average person (I think
> >
> > European
> >
> > > DVD's use 5.1 MP3 or something perhaps).
> > >
> > > 3) It seems formats like Dolby Digital and DTS are not being pushed
onto
> > > consumers very hard. Show me where I can get a DD or DTS encoder to
> > > encode my files. I'm not so sure you will see this pushed on to people
> > > either.
> > >
> > > 4) I really have no idea if formats like WMA and others support 5.1.
But
> > > I can't think of any of these as being too friendly to the average
person
> >
> > this
> >
> > > way either.
> > >
> > > 5) It's really easy to add 5.1 support to an Ogg encoder, and it will
be
> > > available widely.
> > >
> > > 6) On the PC writing or extending a player to handle 5.1 audio would
be
> > > pretty easy, if a sound card supports it (e.g. something like an SB
Live
> > > 5.1).
> > >
> > > 7) There was talk earlier of why a PS1/PS2 could or couldn't handle
> > > Vorbis playback as an entertainment device. I've been thinking about
this
> > > a lot lately, and I think this would be excellent. A PS2 player could
be
> > > written that plays Vorbis files. This player could also do real-time
DTS
> > > or Dolby Digital encoding. So if a user plays a 5.1 format Vorbis
file,
> > > the PS2 switches into DTS output mode, decodes the Vorbis into 5.1,
and
> > > then re-encodes it into DTS 5.1 and sends it out the optical. The
> > > re-encoding
> >
> > may
> >
> > > introduce a bit of artifact, but not likely if done right. You then
get
> >
> > the
> >
> > > benefit of a digital connection to your 5.1 setup. I know I use my PS2
a
> >
> > lot
> >
> > > to play CD's, just because it has a digital connection. But Sony's CD
> >
> > player
> >
> > > is a horrible thing and I hate changing CD's every 45 minutes. I'd
really
> > > like to copy 15 or 20 albums onto a CD and let it rip through a good
> >
> > Vorbis
> >
> > > player (of course it could play MP3's, etc., as well). I'd really like
to
> > > start a project like this myself, but I fear two problems 1) Sony
would
> >
> > not
> >
> > > approve such a player, since it allows the possibility of playing
pirated
> > > music (hey Sony is a big music company), and 2) I'm not sure the PS2's
> >
> > laser
> >
> > > can read CD-RW discs. I think it can read CD-R's but I'm personally
not a
> > > big fan of only burning something once. Other than those logistical
> > > issues
> >
> > I
> >
> > > think the technology is pretty simple. I know I'd be willing to spend
$30
> >
> > on
> >
> > > some PS2 player software that would transform my PS2 into a wicked
high
> > > quality audio player.
> > >
> > > Thanks,
> > > Dave.
> > >
> > > -----Original Message-----
> > > From: Andreas Karlsson [mailto:a.karlsson at bredband.net]
> > > Sent: Wednesday, November 14, 2001 12:36 PM
> > > To: vorbis at xiph.org
> > > Subject: RE: [vorbis] Multichannel files
> > >
> > >
> > > Hi Myles,
> > >
> > > Thank you for your reply. I´m indeed very serious about trying to make
> > > music in surround.
> > > I find it a very intresting way to extend the expression of music. As
> >
> > every
> >
> > > one knows,
> > > stereo is made to make the soundscape whider and more expressive,
> > > surround will add
> > > new ways to place the listner in the center and carry him/her away.
> > > I´ve now read the threads and I´m not trying to make any technical
> > > suggestions. I´m just
> > > experssing my desire to find new fronteirs.
> > >
> > > Regards,
> > > Andreas Karlsson
> > > http://www.ft2.net
> > >
> > > At 15:03 2001-11-14 -0500, you wrote:
> > > >Hello Andreas,
> > > >
> > > >There was a few threads some months ago on multi-channel oggs and
> > > > various surround formats.  I suggest you search the mailing list
> > > > archives for the word 'ambisonics'  You should find relevant threads
in
> > > > that era.
> > > >
> > > >I have some issues with current surround sound recordings as they
lack
> > >
> > > phase
> > >
> > > >and position information in the sound matrix.  If you are serious
about
> > > >proper surround recordings It will take some effort on the part of
the
> > > >vorbis project and current players to keep and reproduce proper
> > > >phase/location data.
> > > >
> > > >Myles
> > > >
> > > >-----Original Message-----
> > > >From: Andreas Karlsson [mailto:a.karlsson at bredband.net]
> > > >Sent: Wednesday, November 14, 2001 13:58
> > > >To: vorbis at xiph.org
> > > >Subject: [vorbis] Multichannel files
> > > >
> > > >
> > > >Hi,
> > > >
> > > >As I´ve understood things, the Ogg Vorbis format supports more that
two
> > > >channels (stereo). Is there any tools to encode x sourcefiles into
one
> >
> > .ogg
> >
> > > >file?
> >
> > --- >8 ----
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