I made package 'binary-class-exif' It does nearly the same that racket-mediafile, but uses binary-class, and so may write changes back
I cant't understand, why it gives different result for exif:user-comment when reading canon-ixus.jpg from examples from racket-mediafile. binary-class-exif gives 136 zeros racket-mediafile gives #(undefined-type 136 #"*\2\0\0")) Sun, 15 Jun 2014 21:59:24 -0400 от Neil Van Dyke <n...@neilvandyke.org>: >Roman, this looks good. > >I think one good test of your abstractions would be to parse JPEG Exif >with some MakerNotes. IIRC, you have to things like read a value that >is an offset from some other position (from top of file, start of >header, current position...), to follow linked lists, and to have >conditionals. > >Another test would be getting video metadata out of popular video stream >and container formats. This would also be very useful for working with >video files. > >Some documentation references are here: >http://www.neilvandyke.org/racket-mediafile/#%28part._.Content_.Types%29 >I didn't come up with a generalized high-level abstraction, but looks >like you're on your way to doing it better than I did. > >Neil V. > >Roman Klochkov wrote at 06/15/2014 02:42 PM: >> I've written universal library for parsing binary files or their parts >> into Racket objects. >> You may install it with 'raco pkg install binary-class'. This >> library >> has verbose documentation and easy syntax. >> You simply describe your data in terms of class fields and load the >> object from the file. >> >> I've written parsers for MP3 ID3 tags (binary-class-mp3 package) and >> DBF files (binary-class-dbf package, no docs yet, only Readme at >> https://github.com/Kalimehtar/binary-class-dbf ). You may treat them as >> usage examples for the library. >> >> Please, give me feedback. Maybe I can do something better, or maybe >> somebody write another file format to the library. >> >> >> -- >> Roman Klochkov > -- Roman Klochkov
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