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File Formats

Thu, 2006-04-20 07:35 — Matthew Davidson
What is a File Format?

A file format is essentially the set of rules for turning information into zeroes and ones and vice versa.

See Wikipedia's article on file formats.

Proprietary Formats

A proprietary file  format is one where this set of rules is not freely useable by everybody, for one or more reasons such as:

Document FormatsRecommended
  • ASCII/Unicode text. Most applications will have an option for saving files as "plain text"; some will allow you to specify the character encoding used. ASCII is the oldest, simplest, and most widely supported (which is why it is the standard used by Project Gutenberg), although it's support for languages other than English is minimal. Unicode is a set of different plaint text character encodings designed to address this issue. ISO 8859 is another often-used character encoding that is generally considered to have been superceded by Unicode. Document formats which are based on plain text, such as SGML and XML document types, by necessity use one of these character encodings. UTF-8 appears to be the Unicode variant recommended for most purposes (anybody disagree?).
  • PDF. An open standard developed by Adobe Systems. It's often called "Adobe Acrobat format", which creates the misleading impression that proprietary software is required to use it, so please avoid that term. Where in the past it would have been possible to recommend the use of PDF without reservation, it appears that Adobe is up to something with regards to licensing either non-standard extensions to PDF, or ideas in the standard PDF specification which may or may not be covered by patents.
  • (X)HTML. The recommended option for rich formatted documents published electronically. If someone has a web browser, which means practically anyone who has a computer less than a decade old, they can read an HTML document.
  • OpenDocument. An open standard for "office" documents (word processing, spreadsheets, etc.).
Acceptable
  • RTF. A standard for rich formatted text developed by Microsoft.
  • DocBook. A document type of either SGML or XML (similar to HTML, but much more powerful). Often used by professional writers, particularly technical writers, but a bit outside the mainstream.
  • TeX, Groff, Texinfo. Formats for hard-core geeks to have flamewars over.
Avoid Graphics Formats
  • Bitmap and Vector images
  • Compression [lossy|lossless]
RecommendedAcceptableAvoid 
  • Windows Bitmap
  • XBM/XPM
  • TIFF
  • JPEG
  • GIF
  • PNG
  • SVG
  • SWF
  • DXF
  • XCF
  • PSD
  • PSP
Audio FormatsUncompressed
  • WAV (MS)
  • AU (Sun/Unix)
  • AIFF (Apple)
  • BWF
Lossy
  • mp3
  • ra
  • wma (also lossless)
  • OGG Vorbis
  • Musepack
  • Speex
Lossless
  • FLAC
Video formats
  • AVI (MS, obsolete)
  • MOV (QuickTime)
  • MPEG-2
  • MPEG-4
  • RealVideo (.rm)
  • Ogg Theora
  • Dirac