[ogg-dev] Re: [Vorbis] metadata
ibm21 at cam.ac.uk
Thu Nov 17 08:26:13 PST 2005
Ralph Giles wrote:
> On Sun, Oct 02, 2005 at 07:50:25PM +0100, Ian Malone wrote:
>>It's not clear to me what the type should be,
>>"<?xml version='1.0'?>" is clear enough to determine XML, but the
>>header should probably indicate the type of stream.
> Right. The XML declaration provides enough information for a muxer
> to hand off the stream to an xml parser, analogous to how stream
> identification can be done with our other codecs. Requiring this
> should probably be part of a general XML-in-Ogg spec or best
> practices document.
> Also having a doctype or namespaced root element in the initial
> packet to further identify the stream data is, as you suggest,
> another good idea. I'd make that a SHOULD.
CMML may have more on this (a document I should read properly
sometime), but it seems that a way of specifying a logical stream
via a URI would be useful too. Within rfc3986 the query or
fragment components could be used. Both have problems; fragment
prevents us further specifying a fragment within a logical stream,
query's meaning seems to be determined by the scheme (also a
problem with using part of the path). Fragment would also (as I
understand) conflict with CMML's use, query might conflict.
Another possibility is a scheme solely for use within ogg streams,
so ogg:6789abcd (the semantics here aren't quite right) is a
relative reference to the stream with serial:6789abcd. Then
ogg:6789abcd/#dolphin refers to id=dolphin in that stream,
ogg:/#dolphin refers to id=dolphin in the physical stream.
Defining a scheme is probably a long and difficult task, and
with such limited use it doesn't make much sense (it would
hardly be uniform).
Query is the most attractive;
but I don't yet understand if this is compatible with existing
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