[CREATE] XMP : MakerNote

[Hubert Figuiere]

Cyrille Berger wrote:

> I am currently working on XMP for Krita, and Gilles Caullier has told me that 
> one problem with XMP for photograph is that it can't serialize Makernote 
> (small binary chunks inside exif which can be used to manufacturers to extend 
> the exif specification to include more information). And searching in google 
> for XMP and Makernote, you can see that quiet a lot of people are complaining 
> about that.
> The problem about those Makernote is the unavailability of their 
> specification, some effort has been made to reverse engineered them (a 
> summary of the effort is available at exiv2 website: 
> http://www.exiv2.org/makernote.html), but the result is far to be exhaustive, 
> so there is need to keep the old makernote data chunk with the hope, that in 
> the future more information can be exctracted from it (and anyway it's needed 
> to save back to exif).
>
> So I propose, one schema for the data chunk:
> uri: http://create.freedesktop.org/xmp/MakerNote/1.0
> prefix: mkn
>
> With only value:
>
> RawData as a String with the MakerNote encoded in base64

I'm not sure if it fits into XMP and if it is really the way to go.
Including the blob does not solve any problem, even future. Because said
data is still in the corresponding Exif, there is no interest in having
it undecoded in the XMP.

> 
> Then as many schema as specification, with an uri of the form 
> http://create.freedesktop.org/xmp/MakerNote/MANUFACTURER/VERSION
> 
> For instance, for Canon (http://www.burren.cx/david/canon.html)
> http://create.freedesktop.org/xmp/MakerNote/Canon/1.0
> 
> With tags beeing:
> ImageType as string
> FirmwareVersion as string
> ImageNumber as integer
> OwnerName as string
> CameraSerialNumber as integer
> MacroMode as boolean
> Quality as choice
> FlashMode as choice
> ...
> 
> What do you think ?

XMP is *semantic*. That means what is interesting is not the content but
the meaning. In short Maker Notes would have to be translated into
something meaningfull.  That's almost what the second part tries to
address, but I don't think it is the right way. It should be maker
independent properties, ie not a separate namespace for each manufacturer.



Hub