free software formats are not proprietary by definition

Posted Jul 13, 2005 6:42 UTC (Wed) by dvdeug (subscriber, #10998) [Link]

In the real world, the fact that only one program reads/writes this format does matter. Even at best, you have to have programming skill and patience to reimplement a format, and many formats rarely convert to other formats of the same type in a lossless manner. If you've stored your data in one word-processing format, other word-processors that don't work like the one you use may have a hard time preserving your data when loaded.

In many cases, a file format may be a full programming language that is very hard to translate to another file format, and keep changing from version to version. Lilypond and POV-Ray (yes, it's not completely free software) are examples of this. To interact with their files, not only would you have translate a subtle complex system conceptually wrapped around the internals of the program, you would have to keep updating it.

At worst, you're dealing with a poorly documented fileformat that is basically a dump of the internals of the program. That doesn't magically become easy to port just because you can see the code. If the code base is still be worked on, it can become nigh impossible to maintain compatibility.

Sure, you can just read the code, but you can always just reverse engineer a proprietary file format. For the end-user, and even for a programmer, free software formats can very well be proprietary. For example, there is no way to convert a Lilypond file to another format, and nothing besides Lilypond will read the file. Since Lilypond is a nontrivial system layered on TeX (itself a nontrivial, hard to parse, system), if you have a Lilypond file, you can more or less give up on getting it into another music layout system without retyping it. That's, for all intents and purposes, proprietary.