[ogg-dev] Peer review draft for the new

Martin Leese martin.leese at stanfordalumni.org
Mon Oct 1 22:23:44 PDT 2007

"Silvia Pfeiffer" <silviapfeiffer1 at gmail.com> wrote:
> First though let me start a discussion on skeleton here, which is
> fundamental to this rfc and for which I'd like to get more input from
> everyone.
> I think, "application/ogg" makes not much sense without having
> skeleton inside the ogg file. Half the reason for having a generic,
> free-ended encapsulation format is to have headers that can specify
> what is within such that any decoder has a chance to assess whether it
> will be able to do something sensible with it. So, I would like to
> actually prescribe the use of skeleton in application/ogg files.
> Just to be clear - I would not prescribe skeleton for audio/ogg files
> with ogg extension, which are clearly the old vorbis 1 files only. Or
> to spx files, which are speex files under audio/ogg. But "SHOULD"
> should work for audio/ogg with oga extensions without getting anyone
> into trouble.
> Opinions anyone?

I am an outsider here, but sometimes that helps.

When I first read the Ogg Skeleton stuff, my
reaction was "you mean the Ogg container
doesn't have this built in?"  I would suggest
some general principles:

1.  Ogg Skeleton should be as mandatory as
    possible without breaking significant numbers
    of existing files in the wild.

    There are obviously loads of Ogg Vorbis out
    there.  If there are only a few Ogg speex files
    in the wild then they are better handled by a
    tool to automatically convert.

2.  Following on from 1, a tool which inputs an
    Ogg containier with one or more streams, and
    outputs a new Ogg container with the same
    streams plus an Ogg Skeleton stream stuffed
    in front would be very helpful.  The tool could
    also select and create the appropriate file

3.  You can't discuss Ogg contents without also
    discussing the minimum requirements for Ogg
    players.  I would suggest it is time to bite the
    bullet and specify that players must recognize
    and decode an Ogg Skeleton stream if

    At the moment, Ogg Skeleton can break
    existing players.  This has got to change if
    Xiph is to move forward.  Existing player
    developers will need support to do this, and
    you will lose a few who can't/wont do it, but it
    has to be done.  Discussion should be about
    "when" and "how", not "if".

Martin J Leese
E-mail: martin.leese at stanfordalumni.org
Web: http://members.tripod.com/martin_leese/

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