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Re: ACTION-76 : Question if MPEG-21 Part 17 got registered on IANA as a media mime type for fragments

From: Cyril Concolato <cyril.concolato@enst.fr>
Date: Wed, 26 Aug 2009 09:32:50 +0200
Message-ID: <4A94E522.4070001@enst.fr>
To: Yves Lafon <ylafon@w3.org>
CC: Media Fragment <public-media-fragment@w3.org>
Hi Yves,

Yves Lafon a écrit :
> 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? 
No, application/mp21 is the file format based on the ISO base file format. The XML description format in MPEG-21 called DID has, to my knowledge, no registered mime type.

> And what is the relation with EXIF and XMP?
I don't know how to answer this question. 

> Side question, what is the patent policy for MPEG21-Part17 and Part2 
> (ie: are there different policies depending on the parts)?
I don't think there are different policies for different parts. I think both follow the usual ISO rules. I don't see any patent statement in Part 17, which does not mean there aren't any patent, it just means people did not declare any.

>> 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,
I think that's what MPEG did (not me). As I said, I don't know if the process was right. I just wanted to mention that fact.


Cyril Concolato
Maître de Conférences/Associate Professor
Groupe Mutimedia/Multimedia Group
Département Traitement du Signal et Images
/Dept. Signal and Image Processing
Ecole Nationale Supérieure des Télécommunications
46 rue Barrault
75 013 Paris, France
Received on Wednesday, 26 August 2009 07:33:15 UTC

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