albrecht at act-net.com
Mon Mar 15 04:22:57 CST 2004
> OK this is a stab in the dark, but is anybody here familiar with what is
> required to read/write IPTC style metadata to/from various type of media
> files and if it is 'doable' (and practical) with Rev. Any pointers in
> the right direction would be greatly appreciated.
Handling IPTC is my daily business. One of the applications I sell for a
living is a complex image import system running on Linux that handles
IPTC parsing for image agencies (along with various image modifications).
A good start to deal with IPTC is http://www.iptc.org - you could also
have a look into Adobe's Photoshop Imagefile description documents since
many applications simply use an APP13-marker ("Photoshop" chunk) to
include IPTC data into images. Unfortunately Adobe is moving towards XMP
now so all IPTC-talkers have to switch techniques some time soon.
Porting my simple IPTC-read/write routines to Runrev was a project I
wanted to do to get used to Transcript. I failed completely because I
don't get the switch with Transcript (it's not a programming language to
me), so I have to wait until my usual biz gives me more time to drink
lots of coffee and re-try to get warm with Transcript. BUT in general it
should be a very easy job to parse an IPTC struct, which is (embeded in
some chunk or another - like an APP13 chunk) basically this:
BYTE marker (0x1c)
BYTE tag (see IPTC doc)
BYTE field (see IPTC doc)
WORD length (MSB first)
DATA (of "length" BYTEs)
Depending on the surrounding structure you often have a
"Pascal-length-encoded string" just before the structure itself.
Sometimes applications vary the length of data sets to match even
offsets in the chunk.
Feel free to contact me if you need specific help for a project.
A.C.T. / level-2
Glinder Str. 2
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