mime types and video/audio files (was Re: Review of the thumbnailer spec)

[A. Walton]

On Tue, May 19, 2009 at 4:57 PM, Brian J. Tarricone <bjt23 at cornell.edu> wrote:
> A. Walton wrote:
>
>> Just as a note, this is precisely the rationale behind "Uniform Type
>> Identifiers", which support multiple inheritance and uses the
>> currently-in-vogue reverse DNS naming scheme (e.g. you can have types
>> like "com.my-media-encoder-company.complex-video-type" conform to
>> org.xiph.vorbis, com.bbc.dirac, org.xiph.ogg-kate,
>> org.xiph.ogg-container,  public.utf8-plain-text, public.movie,
>> public.video,  public.plain-text, public.audiovisual-content,
>> public.composite-content, public.content, and public.data in a tree
>> structure which should be rather deducible from the order they are
>> given here).
>
> Is a single file allowed to have multiple UTIs?  A mkv file might have
> *all* of org.matroska.mkv-container, org.xiph.theora, org.xiph.vorbis,
> and com.dolby.ac3, for example.

It's not so much said that a file has multiple UTIs, only that the
file conforms to them. The actual UTI for a complex video format is
rather abstract (it doesn't even have to have a name; it can be some
vague "dynamic" type that only the system knows about). The important
part is whether the UTI for the file conforms to the type you want.

As a couple of examples: an XML editor wants to be able to look at all
public.xml files, however your XHTML document editor only wants to
look at public.xhtml files, and your SVG editor only wants to look at
public.svg files, but both XHTML and SVG conform to XML, so the XML
editor will see both. A video thumbnailer could be even more picky:
I'm able to thumbnail videos that conform to
org.matroska.mkv-container, org.xiph.ogg-container, org.xiph.theora
and com.bbc.dirac. Then your hex editor can just look at anything that
conforms to public.data (the highest level object).

-A. Walton

>
>        -brian
>
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