[ogg-dev] Ogg metadata stream embedding

Silvia Pfeiffer silviapfeiffer1 at gmail.com
Wed Sep 12 00:49:22 PDT 2007

I suggest using the solution that CMML has come to use.

The XML file is essentially the same as an unencapsulated physical bitstream.

Then there is a mapping into a logical bitstream, where some of the
default information - in particular the XML header - are split off and
put into the bos packet - nothing really needs to go into the eos
packet. There's also a magic number and a version number.

Also, use the granulepos scheme that we defined for CMML pages- you're
going to make your lives easier.

CMML has had several years of fine tuning of the means to encapsulate.
Don't underestimate the problems - it's very easy to get the
impression that XML is simple to handle, while it's actually quite
hard to get right.

So much for technical feedback.

Now I just ask myself the question as to what "Ogg Metadata" really is
- since that wiki page has no actual technical specification on it at


On 9/12/07, Ian Malone <ibmalone at gmail.com> wrote:
> Another spin-off discussion.  The scheme used on
> <http://wiki.xiph.org/index.php/Metadata> was to
> packetize XML (split it up into packets at the
> root level, each of which was self contained
> (the terminology has temporarily abandoned me),
> and have the bos packet as the opening <?xml
> &c. stanza, the eos a </xml>.
> It is probably more sensible to include a magic
> number identifying it as a metadata stream
> and probably a version number.  I wouldn't
> anticipate that version number being bumped
> in the near future as it would mostly guarantee
> simply:
> 1.  An XML metadata stream.
> 2.  That some form of the currently debated
>      metadata format would be present.
> Anything I've missed?
> This only leaves arguing over the magic number.
> I like MOG (Metadata in OGg), but it's far too
> short...
> --
> imalone
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