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<div>I've added Christian here, who actually authored the
document.</div>
<div><br></div>
<div><br></div>
<div>At 8:50 +0100 14/05/07, Graham Klyne wrote:</div>
<blockquote type="cite" cite>I have a couple of comments:<br>
<br>
(1) the "Encoding considerations" section appears to confuse
MIME requirements<br>
for text with encoding for transmission over non-binary channels.
A MIME<br>
content transfer encoding of "Binary" would be sufficient to
indicate<br>
prohibition of CR/LF conversion or 7-bit stripping.</blockquote>
<div><br></div>
<div>I think this text was copied from other MIME registrations.</div>
<div><br></div>
<blockquote type="cite" cite><br>
(2) the subtype name -- if I recall correctly, MPEG-21 uses an XML
encapsulation<br>
layer (MPEG21-DIDL) for assembling various subparts into a composite
for<br>
transmission (unfortunately, lack of a freely available online version
of the<br>
cited document means that I can't check this). If I am correct
here, then it</blockquote>
<blockquote type="cite" cite>may be more appropriate to use content
type name "application/mp21+xml".</blockquote>
<div><br></div>
<div>Correct, the main document inside the binary archive is indeed in
XML. But the overall file format is binary. Doesn't the
mime type "+xml" suggest that the document is specialized
XML only (i.e. a text document)?</div>
<div><br></div>
<blockquote type="cite" cite><br>
Also, if I recall correctly, the use of BASE64 for binary components
within an<br>
MPEG21-DIDL XML wrapper is covered by the MPEG21 specification itself,
so it may<br>
be quite inappropriate to suggest Base64 encoding applied at the MIME
level.</blockquote>
<div><br></div>
<div>The file format contains the XML, and also the attached binary
resources, outside the XML but inside the file format. They are
not (necessarily or normally) encoded at all.</div>
<div><br></div>
<blockquote type="cite" cite><br>
It would be very much easier to give useful review if there was at
least a<br>
publicly web-accessible summary of what this content type is expected
to convey.</blockquote>
<div><br>
Sure. There are brief intros at</div>
<div><br></div>
<div><http://www.chiariglione.org/mpeg/mpeg-tech.htm>;
have a look at</div>
<div><font face="Verdana" size="+2" color="#0E0180">ISO Base Media
File Format</font></div>
<div>and specifically:</div>
<div><font face="Verdana" size="+2" color="#0E0180">Digital Item File
Format</font></div>
<div><br></div>
<div>The base file format specification contains a lot of otehr stuff
as well (stuff MPEG-21 doesn't use), but if you want to view it, it is
freely available</div>
<div><br></div>
<div
><http://isotc.iso.org/livelink/livelink/fetch/2000/2489/Ittf_Home<span
></span>/PubliclyAvailableStandards.htm></div>
<div>and find 14496-12</div>
<div><br></div>
<div>Christian may well have introductory material as well.</div>
<div><br></div>
<div>Hope that helps.</div>
<div><br>
<br>
</div>
<blockquote type="cite" cite><br>
#g<br>
--<br>
<br>
<br>
Stephan Wenger wrote:<br>
> That's Dave Singer as the contact, of course. Sorry for the
typo.<br>
> Stephan<br>
><br>
> On May 14, 2007, at 6:33 AM, Stephan Wenger wrote:<br>
><br>
>> Folks,<br>
>> MPEG (ISO/IEC JTC1 SC29) sent us an liaison statement asking
us to<br>
>> review their draft for a MIME registration of the MPEG-21
file<br>
>> format. I know nothing about the subject matter, but
hope some of you<br>
>> could give them a hand. Please direct any technical
questions to Save<br>
>> Singer of Apple, singer@apple.com
<mailto:singer@apple.com>. Below,<br>
>> please find what I believe they want to register. Their
full liaison<br>
>> statement (in a bunch of word files) can be found<br>
>> here: https://datatracker.ietf.org/public/liaisons.cgi, look
for<br>
>> ISO/IEC JTC1 SC29, May 2007<br>
>> Best regards,<br>
>> Stephan<br>
>><br>
>>> MIME media type name: application<br>
>>> MIME subtype name: mp21<br>
>>> Required parameters: none<br>
>>> Optional parameters: none<br>
>>> Encoding considerations: base64 IS generally preferred;
files are<br>
>>> binary and should be transmitted without CR/LF
conversion, 7-bit<br>
>>> stripping, etc.<br>
>>> Security considerations: It is possible to inject
non-compliant MPEG<br>
>>> streams (Audio, Video, and Systems) in the MP21 file to
overload the<br>
>>> receiver/decoder's buffers. This might compromise the
functionality<br>
>>> of the receiver or even crash it.<br>
>>> An MP21 file supports the storage of stream types,
including commands<br>
>>> that are executed on the terminal such as Digital Item
Methods based<br>
>>> on ECMASCRIPT for which also bindings to Java(TM) and C++
exists. It<br>
>>> is possible to use one or more of the above in a manner
non-compliant</blockquote>
<blockquote type="cite" cite>>>> to MPEG to crash the
receiver or temporarily make it unavailable.<br>
>>> Authentication mechanisms can be used to validate of the
sender and<br>
>>> the data to prevent security problems due to
non-compliant malignant<br>
>>> MP21 files.<br>
>>> Interoperability considerations: A number of
interoperating<br>
>>> implementations exist within the ISO/IEC 21000 community,
and that<br>
>>> community has reference software for reading and writing
the file format.<br>
>>> Published specification: ISO/IEC 21000-9:2005<br>
>>> Applications which use this media type: Multimedia<br>
>>> Additional information:<br>
>>><br>
>>> Magic number(s): none<br>
>>><br>
>>> File extension(s): mp21 and mpg21 are both declared
at<br>
>>> http://pitch.nist.gov/nics/ and http://filext.com/<br>
>>><br>
>>> Macintosh File Type Code(s): mp21 is registered with
Apple.<br>
>>><br>
>>> Person & email address to contact for further
information: David<br>
>>> Singer, singer@apple.com
<mailto:singer@apple.com><br>
>>> Intended usage: COMMON<br>
>>> Author/Change controller: David Singer, ISO/IEC 21000
file format chair<br>
><br>
<br>
--<br>
Graham Klyne<br>
For email:<br>
http://www.ninebynine.org/#Contact</blockquote>
<div><br></div>
<div><br></div>
<x-sigsep><pre>--
</pre></x-sigsep>
<div>David Singer<br>
Apple Computer/QuickTime</div>
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