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kaitai-io / kaitai_struct_formats

Kaitai Struct: library of binary file formats (.ksy)
http://formats.kaitai.io
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Add JPEG Interchange Format (JIF) file format #141

Open davidhicks opened 7 years ago

davidhicks commented 7 years ago

Documentation on the file format: https://www.w3.org/Graphics/JPEG/itu-t81.pdf

Branch containing draft specification: https://github.com/davidhicks/kaitai_struct_formats/tree/jif

Sample/test files: https://www.itu.int/net/itu-t/sigdb/speimage/ImageForm-s.aspx?val=1010083

davidhicks commented 7 years ago

This format is the basis for more commonly known formats JFIF and EXIF.

It would probably be best if #156 were addressed before development of this JIF .ksy specification continues. In the JIF format, a multi-byte code is used to denote the start of a type of section of the file format. Whilst it may be possible to write a .ksy specification that handles this, the result will be quite complex, hard to understand and ugly to read. It would be better if either #156 was available, or a new feature like optional: true were available to perform a look-ahead read on the stream to see what data type is required to be used to interpret the next bytes in the stream. See #167 for another example of where optional: true could be useful.

davidhicks commented 7 years ago

We also need to think about how JFIF and EXIF could extend or otherwise use the types defined in this base JIF format, avoiding duplication as much as possible.