MediaTypeReview

Being able to address issue 3 properly, we review media types (audio/*, image/*, video/*) here on this page regarding mentioning of any fragment/anchor identifiers and semantics along with it.

Goal and Input

The goal is to find out if there are any media types registered with IANA that contain '... information about how fragment/anchor identifiers [RFC3986] are constructed for use in conjunction with this media type.' as defined in RFC4288 (Media Type Specifications and Registration Procedures). We hence use as an input:

• the audio/*, image/*, video/* branches at http://www.iana.org/assignments/media-types/ and the respective RFCs below that register media types
• Section 4.11. Additional Information from RFC4288

Process and Results

In a first step the entire audio/*, image/*, video/* branches are mirrored locally using httrack:

httrack http://www.iana.org/assignments/media-types/audio/
http://www.iana.org/assignments/media-types/video/ 
http://www.iana.org/assignments/media-types/image/ -W -O 
"/Users/michau/Documents/W3C/MediaFrag/iana/" -%v -r2  

Then we run a script that searches for 'fragment/anchor identifiers' occurrences:

grep -r "fragment" iana/ > fragment-occurrance.txt
grep -r "anchor" iana/ > anchor-occurrance.txt
grep -r "fragment identifier"  iana/ > fragment-identifier-occurrance.txt
grep -r "anchor identifier"  iana/ > anchor-identifier-occurrance.txt

The results (for fragment and for anchor) suggest that there is NO single media type in the audio/*, image/*, video/* branches that is defining fragments or fragment semantics along with it. Though there are media types that talk about fragments, it can be assumed that there are no clashes with our proposed work. Further, although MPEG-21 Part 17 seems to propose a normative syntax for selected media types (such as audio/mpeg) there are no indications that these have been registered and/or updated by ISO with IANA.

Conclusion

From a Web architecture point of view there are no restrictions or clashes with other standards. We are free to propose or register the semantics for certain or all audio-visual media types. However, to foster wide-spread adoption it might be more advisable to approach owners of major media types with a cover letter explaining our work and motivate them to update their respective media types accordingly.

Resources

• AWWW1 - Representation Types and Internet Media Types, W3C Recommendation 15 December 2004
• Mapping between URIs and Internet Media Types, TAG Finding 8 April 2002 (Revised 27 May 2002)
• Improving Media Fragment Integration in Emerging Web Formats, Lloyd Rutledge and Patrick Schmitz, Proceedings of the 8th International Conference on Multimedia Modeling, November, Amsterdam, Netherlands, September 2001
• RFC4288, section 4.11 Additional Information, IETF Best Current Practice, December 2005
• IANA media type registry