[Jack-Devel] well-known meta-data

As the metadata API and jack1 implementation moves along, it would be
useful to define a (small) set of standard names (URIs) for metadata key
names that software (and users) might reasonably anticipate seeing.
"Well-known metadata" or WKM might be a term for it.

Metadata consists of a key and a value. The value has a MIME type, which if
empty is assumed to be text/utf-8. The key is a string that is intended to
be a URI (but need not be).

Dave Robillard and myself imagined that benefit of using URIs as the keys
is that we can make them self-documenting. With this in mind, I propose the
following initial well known keys/URIs:

http://jackaudio.org/metadata/pretty-name
      pretty-name, if defined as a port metadata key, has the value that
should be shown to the user when displaying a port to the user, unless the
user has explicitly overridden that a request to show the port name, or
some other key value.

http://jackaudio.org/metadata/hardware
      hardware, if defined as a port metadata key, has the value that
should be shown when attempting to identify the specific hardware outputs
of a client. Typical values might be "ADAT1", "S/PDIF L" or "MADI 43"

http://jackaudio.org/metadata/connected
       connected, if defined as a port metadata key, has a value that
identifies what the hardware port is connected to (an external device of
some kind). Possible values might be "E-Piano" or "Master 2 Track".

http://jackaudio.org/metadata/icon-small
        icon-small, if defined as a port client metadata key, has a value
with a MIME type of "image/png;base64" that is an encoding of an NxN (with
N <=32) image to be used when displaying a visual representation of that
client or port

http://jackaudio.org/metadata/icon-large
        icon-large, if defined as a port or client metadata key, has a
value with a MIME type of "image/png;base64" that is an encoding of an NxN
(with 32 < N <= 128) image to be used when displaying a visual
representation of that client or port

I would welcome a discussion on the general design, on these specific WKM
names, and on others that people think may warrant a URI within the
http://jackaudio/metadata space.

--p

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