[Bug 17673] Define Initialization Data for implementations that choose to support the ISO Base Media File Format

https://www.w3.org/Bugs/Public/show_bug.cgi?id=17673

--- Comment #42 from David Singer <singer@apple.com> ---
Two comments in one.

a) we get requests to expose in the MIME type string all sorts of information
from the file.  Does it have closed-captions in SEI format in the video stream?
 Are fragments limited to a maximum size?  Are certain boxes present or absent?
 Does it use 64-bit variants of some features?  Does it require support for
some encryption formats?  The 'codecs' string was introduced to answer
questions about the codecs specifically, but can't answer all these others. 
However, it is possible to write specifications that set these requirements,
and they can define a brand that goes in the ftyp/styp boxes, to indicate that
the file claims compatibility, and those compatible brands can be listed in the
MIME type (the 'profiles' parameter). We could keep loading specific features
into the mime string for years, but I think it may be better to write these
'portmanteau' specs that roll up a whole bunch of stuff, and then label the
file as conforming to those.  We could even define such a profile and brand in
the MSE spec itself.

b) but, as noted in email today, the spec. rather bizarrely expects (requires?)
that any ftyp/styp in the initialization segment be ignored, a statement that
is currently causing some implementations to strip it, which defeats the
purpose of these compatibility claims. 

<http://www.w3.org/mid/45F3418A-EBB1-461E-8580-4B9354E40BEC@apple.com>

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Received on Tuesday, 18 February 2014 18:23:50 UTC