[vorbis] midi data to control lighting desks

[Beni Cherniavsky]

On 2002-11-24, David K. Gasaway wrote:

> On 24 Nov 2002 at 4:02, Alejandro G. Belluscio wrote:
>
> > Please remember that that code is not Vorbis File Specification I
> > compilant (since it doesn't allows multiplexed ogg files).
>
> This statement is confusing.
>
> 1) Why would an ogg file thatcontains more than just Vorbis streams
> ever be compliant to the Vorbis file specification?It's almost like
> saying Theora isn't Vorbis File Specification I compliant (since it
> doesn't allow video ogg files).
>
Indeed it isn't.  However it could be - in the sense that a Vorbis I
player could be required to ignore any but the first of the multiplexed
streams (assuming the first is a Vorbis stream, of course).  The fact that
it isn't (the spec clearly says a multiplexed ogg is not a legal Vorbis I
file, so decoders are free to choke on them) is considered by many people
an unfortunate shortcumming of the spec.  This shortcomming is backed by
the fact that the official 1.0 decoder doesn't handle mulplixed streams (I
think).  IIRC, Monty said it might be better if the ignore-rest demand
was specified but it's too late to fix anyway.

In any case, everybody who can is encouraged to ignore the other streams
in a multiplexed link so that his software will not choke on Vorbis II
standards when they appear...  Currently everybody is afraid of
multiplexing extra data with Vorbis because Vorbis I decoders will not
parse the result :-(

> 1) How can the Vorbis file specification disallow multiplexed ogg
> files?That would be the domain of the Ogg specifications.
>
The ogg spec defines how to do arbitrary chaining of arbitrarily
multiplexed streams.  It notes that specific applications (e.g. Vorbis)
can make additional limitations.  Vorbis I does exactly that by requiring
that an Ogg Vorbis I file must not be multiplexed.


-- 
Beni Cherniavsky <cben at tx.technion.ac.il>

What's lower level than machine code?  A spreadsheet: not only addresses
are numeric and hand-allocated but also all loops are hand-unrolled and
all calls hand-inlined... (and macros are unheard of, of course).

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