(off-topic) The latest on Vorbis

[Geoff Shang]

Hi folks:

I realise this is off topic, but I know that there are at least some
interested people on this list, and there are small sections that are
relevant.  Feel free to skip this message if you're not interested.

As some of you will know, I have a great interest in the new open-source
audio format that is called ogg vorbis.  Things have been happening a bit
lately, so I thought I'd bring those who are interested up to speed on
where things are at and where they are going.  We're getting to some of the
exciting stuff now, so if you're at all interested, read on.

For those who don't know about vorbis, briefly vorbis is a freely available
and usable audio format which is being developed in the opensource
community, with the intention of escaping the patent fees and other red
tape associated with MP3 and its competitors.  Feel free to drop me a line
with any questions.

		OGG Vorbis 1.0beta4

Vorbis 1.0beta4 is due out shortly.  The problem is that vorbis.com has
been caught up in a rangle between 2 internet companies.  The situation is
being resolved, and has been at any day now status for 2 weeks.  Once it is
back up, beta4 will be released.  Prebeta4 files have been available in CVS
for several weeks, but the developers have taken advantage of the
vorbis.com outage to continue development.  Yesterday however, Monty
announced a freeze for beta4 so that the bugs can be ironed out.

There's not a staggering amount of new stuff in beta4, as development has
once again proved slower than anticipated.  Beta3 introduced some pretty
serious encoder bugs which have now been resolved.  More bugs have been
squashed in beta4, as well as some pretty dramatic speed increases (you can
now encode in realtime or better on some systems and this will continue to
improve).  There are also now better algorythms for VBR bitrate selection.
There's not been much chatter on the development list lately, so the odd
feature or 2 may have been added in the last couple of weeks.  Guess we'll
just have to wait and see.

Vorbis 1.0beta4 is not the release candidate for 1.0 that was hoped for.
2 major features that need to be included are joint stereo and bit pealing,
a technique where you can get higher sampling rates at lower data rates by
simply discarding the right data bits.  Monty, the core developer for the
vorbis libraries doesn't want to rush any of this stuff, so it could be a
little while yet.

In the meantime, a lot has been going on in other areas.  Developers have
been working hard to get vorbis to compile on numerous platforms and
compilers.  It has most recently been patched to compile on Apple's soon to
be released macos X (aka Darwin).  compatibility is probably going to be a
big thing going for vorbis when it's ready for prime time.

		Icecast 2.0 now at prealpha

Icecast is being completely rewritten for version 2.0.  2.0 will stream
vorbis instead of mp3.  For the truly brave, there is already some prealpha
C code to play with.  Unfortunately, icecast.org is caught up in the same
rangle, so it is currently also offline.  The icecast team are hoping for
icecast 2.0 to be ready at the same time as vorbis 1.0 is released.

The ogg vorbis format allows for some pretty exciting possibilities when it
comes to live streaming.  Firstly, because you can (or will be able to)
perform bit
peeling, it becomes trivial to send out a vorbis stream at a lower data
rate than the one supplied to it.  The implications are quite obvious - a
source audio stream could be provided at 128kbps and the server could
determine the correct datarate for a client and send it out at that rate.
People on cable or DSL could get the full 128kbps or near to that, whilst
lower bandwidth users could hear it at a lower rate, all with one server
and all from the one source.

Another thing that looks promising is the fact that the ogg stream and
icecast 2.0 are both designed to handle chained vorbis streams.  This means
that unlike mp3, vorbis players will be able to cope with one vorbis stream
following another one.  The vorbis specification calls for all the
appropriate decoder information to be sent out at the top of the stream, so
a decoder will be able to cope with differing bit rates or sampling rates,
as the information needed to cope with this will be automatically sent out
as part of the vorbis stream.  This will be pretty useful for projects like
ACB radio interactive which suffers from the stream being dropped between
shows, partly for the very reason that MP3 does not deal well with
situations like this.

A number of media players already support vorbis, and will be made to
support icecast 2.0 before it comes out.  There are vorbis plugins for
winamp, sonique freeamp and xmms, plus stand-alone vorbis players doing the
rounds already.  The list will likely grow before vorbis 1.0 is released.

		Realplayer plugin now available

The latest program to have vorbis support is realplayer from realnetworks.
The plugin was written by the vorbis developers, so it's not yet a standard
part of realplayer.  Hopefully it will be one day, but for now I presume it
will be available for download soon, perhaps even with the 1.0beta4
release.  For those who have the realplayer SDK, you can get the plugin
from vorbis CVS and compile it.  For info about vorbis CVS, see
http://www.xiph.org/ogg/vorbis/

		Oddsock DSP plugin for winamp now supports vorbis

Oddsock recently made a plugin to replicate the shoutcast
DSP plugin using lame.  Beta7 is now out and supports the vorbis
format in addition to MP3.
At present, there isn't much use for such a beast as there are no
servers to stream to, but it is ready and waiting for icecast 2.0 and any
others that may appear.  They've also made some improvements to the mp3
stuff too.  If you're into checking out winamp plugins, visit
http://www.oddsock.org/tools/dsp_oddcast/

I've not heard of any work to make any of the icecast streming tools (e.g.
liveice or isis) vorbis compliant, but I wouldn't be surprised to see it
happening soon.

Well, that's about all for now.  Feel free to drop me a line if you have
any further queries about vorbis or any of the related projects - I keep on
top of the relevant mailing lists.

Geoff.