- From: Ralph Giles <giles@xiph.org>
- Date: Tue, 10 Apr 2007 11:58:27 -0700
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. 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. 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.) 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. A <video/> or <audio/> markup element already describes this adequately, but it is a larger issue for media handling on the web. Charles wrote a more detailed proposal in the context of RSS media syndication, which is where I first heard of the idea. http://changelog.ca/log/2005/08/21/rss-disposition-hinting-proposal We're essentially suggesting his proposal be extended to (media) containers in general. -r
Received on Tuesday, 10 April 2007 11:58:27 UTC