<HTML><BODY>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 <neil@neilvandyke.org>: <BLOCKQUOTE style="BORDER-LEFT: #0857a6 1px solid; PADDING-BOTTOM: 0px; MARGIN: 10px; PADDING-LEFT: 10px; PADDING-RIGHT: 0px; PADDING-TOP: 0px"> <DIV> <DIV> <DIV> <DIV>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: <A href="http://www.neilvandyke.org/racket-mediafile/#%28part._.Content_.Types%29" target=_blank>http://www.neilvandyke.org/racket-mediafile/#%28part._.Content_.Types%29</A> 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 > <A href="https://github.com/Kalimehtar/binary-class-dbf" target=_blank>https://github.com/Kalimehtar/binary-class-dbf</A>). 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 </DIV></DIV></DIV></DIV></BLOCKQUOTE> -- Roman Klochkov </BODY></HTML>