Talk: File format
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- The Ogg format can potentially store video and/or audio, but actual implementations are currently rare as of December 2001, and only an audio codec called Ogg Vorbis exists for the format, though developers continue to work on video codecs such as the Tarkin video codec and to integrate other formats such as MNG (lossless and motion-JPEG compression), FLAC (lossless audio compression), and XML (text-based data such as captions and subtitles) into the Ogg framework. IFF is a now defunct format which, like AVI, is a shell, but IFF had no limitations, being able to store sound, image, movie, animation, data or archive. If a programmer wanted to store data in the IFF format, he just had to define the subformat following the general rules. For example, WAV files follow a variation of IFF called RIFF.
Removed, at least temporarily. The main point of including this seemed to be to make the point that some file formats allow storage of more than one kind of information. I have left one or two examples in the article, but I think such an in-depth treatment is excessive, at least considering the current length of the rest of the article. -- Ryguasu
This text:
- The most useful part of intellectual property law for protecting ownership of a file format seems to be patent law. Although you cannot patent a file format, some file formats require encoding data with patented algorithms.
is presumably talking about the laws of a particular country, the USA maybe? Maybe there are countries where it's possible to patent a file format, but patenting algorithms as such is not permitted in many places.
Yes, I was thinking about US law, which is not an altogether bad starting point, given the importance of US software developers. But a more international perspective is certainly in order. --Ryguasu
Data format
This article is about data formats in general, not only file formats: it should be renamed. For instance JPEG is a data format but not a file format (JFIF is a file format using JPEG, TIFF is another one). A data format is required to exchange data, a file is only an exchange mean, that is not always used. It is quite common for a server to generate data in some format (say MPEG) and send it to a client for immadiate use, with no file storage at any point in the process. Marc Mongenet 18:37, 2004 Aug 30 (UTC)
Incorrect HTML magic number, HTML files should start with <!DOCTYPE
An HTML file, for instance, should begin with the ASCII characters <html>
This is not correct. HTML and XHTML documents should start with a DOCTYPE declaration.
See http://www.w3.org/TR/html4/struct/global.html#h-7.1
--Skjæve 09:21, 14 Sep 2004 (UTC)
- You are of course correct, and I've changed the article to try and reflect this. I've left the mention of <html> in there, though, because if you were testing magic numbers it would be foolish not to look for this: I should think there are an awful lot of HTML files out there that don't include a DOCTYPE, especially hand-crafted ones. - IMSoP 15:46, 15 Sep 2004 (UTC)
- And they are perfectly valid HTML documents that have no
htmltag (and noheadand nobody). They all are optional elements. HTML is the worst example of magic number I can think about. Marc Mongenet 04:35, 2004 Sep 16 (UTC)
- And they are perfectly valid HTML documents that have no
- Or perhaps the best example of the imperfection of the approach! It is, after all, an attempt to apply rules that started off for internal use by readers of binary files, to the much more complex problem of identifying the large range of files on a modern computer. Perhaps a note should be added that this isn't always easy. Anyway, I only used HTML as an arbitrary example of "a file type most readers will have seen and understand", and included it in all three sections for consistency and to aid comparisons. (Although, I'm not sure they are strictly "optional" in terms of Standards-based validity, only in terms of renderability by most "tag soup" parsers, but I see your point) - IMSoP 13:07, 16 Sep 2004 (UTC)
- Both the start and end tags are optional in HTML 2.0, HTML 3.2 and HTML 4.0(1), strict and loose DTD. Worst possible example... Marc Mongenet 20:02, 2004 Sep 30 (UTC)
- Fair enough, I didn't know that. Still, I think you miss my point about what it's a good example of: it's a good example of magic numbers not working. It illustrates their achilles heel, so to speak. I've edited the article now, to explicitly make this point. [The downside being my nice parallel examples are now in different orders in different paragraphs. :( Maybe I'll fix that later.] - IMSoP 22:36, 30 Sep 2004 (UTC)
