On Apr 10, 2007, at 11:58 AM, Ralph Giles wrote:
On Tue, Apr 10, 2007 at 11:21:10AM -0700, Dave Singer wrote:
# application/ogg; disposition=moving-image; codecs="theora, vorbis"
# application/ogg; disposition=sound; codecs="speex"
what is the 'disposition' parameter?
The idea of a 'disposition-type' is to mark content with
presentational
information. See the Content-Disposition Header for MIME described in
RFC 1806 for an early example.
Wouldn't it be simpler to use "video/ogg" and "audio/ogg" as the base
types here? That would already tell you the intended disposition.
The specific proposal Silvia mentioned is to add the content-
disposition to the media-type to inform parsers of the general
nature of the content, even if they don't recognize the specific
codecs. The allowed values for the 'disposition' label come from
the Dublin Core set. This is not part of RFC 4281, and as far as
I know hasn't been formally documented with the IETF, but we do
think it's a good idea.
It seems redundant with the "video/" and "audio/" base types, and
adding such a feature just to make the point that the Ogg container
is universal seems like a stretch.
This arose out of the need to discover or record "audio" vs
"audiovisual" status for media files in the context of routing
to the proper playback application, which has been particularly
contentious with the Ogg container since we have insisted that
such distinctions be made via metadata or file inspection instead
of defining distinguishing filename extensions has has been done
with other containers. (MooV is perhaps another example.)
File inspection is not really workable for content coming from the
web that might be sent to an external app, so I think the Ogg
community should reconsider this stance on distinguishing file types
by primary use.
In terms of user presentation, "audio" vs "video" vs "text" vs
"still image" is the important distinction, while the 'codecs'
parameter answers the more technical question of what playback
capabilities are necessary.
And indeed, MIME already has "audio/", "video/", "text/" and "image/"
base types to make this very distinction. It seems unhelpful to
invent a second way to say the same thing.
Regards,
Maciej
