- From: Yves Lafon <ylafon@w3.org>
- Date: Thu, 23 Jul 2009 08:22:38 -0400 (EDT)
- To: cyril.concolato@telecom-paristech.fr
- cc: Media Fragment <public-media-fragment@w3.org>
On Thu, 16 Jul 2009, Cyril Concolato wrote: Dear Cyril, >>> mpeg-4 and mpeg-21 chose to take the route that the mime registration >>> was merely a registration, a pointer from the code point (the mime >>> type) to the spec. Is that a problem? >> >> Honestly, I'm not in the position to tell if this is a problem, however, >> when I did my review [1] I implicitly was working under this assumption, >> yes. >> >> Anyway, I think we are on the safe side, as the original question was about >> frag IDs in audio/*, image/*, and video/*' and we learned that MPEG21 has >> not registered anything there (but only in their own application/mp21). > You have to make the distinction between the MPEG-21 Part 9 (File Format) and > the MPEG-21 Part 17 (Fragment Identification of MPEG Resources). > > Part 9 defines a file format based on the ISO Base Media File Format. Its > main purpose is to wrap media data with a XML description conformant to > MPEG-21 Part 2 (Digital Item Declaration). Therefore it is registered as > application/mp21. However due to the compatibility with the ISO BMFF, the > same file, if it contains media data and conforms to other specifications, > may be served as audio/mp4, video/mp4 ... I think looking at the MPEG-21 FF > to find the answer to the question on your Wiki is not the right approach. Quick question there, is application/mp21 the XML description format? And what is the relation with EXIF and XMP? Side question, what is the patent policy for MPEG21-Part17 and Part2 (ie: are there different policies depending on the parts)? > On the other hands, Part 17 clearly indicates that it "specifies a normative > syntax for URI Fragment Identifiers to be used for addressing parts of any > resource whose Internet Media Type is one of: > - audio/mpeg [RFC3003]; > - video/mpeg [RFC2045, RFC2046]; > - video/mp4 [RFC4337]; > - audio/mp4 [RFC4337]; > - application/mp4 [RFC4337]". > > Now, I don't know if the process was right, or if such fragment identifier > scheme should appear in the registration forms of those media types but it > seems to me that the important questions are more technical: is this scheme > good or not, is it too complex to implement or not, should it be profiled or > not, extended or not ... Looking at RFC3003, there is no link from it to MPEG21-Part17, so it seems that you defined an inbound link from part7 to the data formats, but not the other way round. Cheers, -- Baroula que barouleras, au tiéu toujou t'entourneras. ~~Yves
Received on Thursday, 23 July 2009 12:22:49 UTC