• DataCompression

Data Compression

Very new wiki, what. This page is about data compression, links to resources, other pages describing algorithms in depth, etc..

Information on data, image, sound and especially video encoding is good too. MPEG and similar standards are commercial and learning material on such are rather expensive, so if you can get substantial articals for posting here.. that's great!

first off, a couple of links. maybe not the best place for them, but you can fix that.

• http://www.datacompression.info

• comp.compression (try http://groups.google.com)

• http://www.nist.gov/dads/ can often be a useful site

On Topic Items

New pages for these, or expand on them in the current page.

• CountingTheory (why your magic compressor will _not_ work)

• Entropy and compression
• Varied width coding schemes
• Fixed width coding schemes
• Dictionary based compression
• Delta compression, mathematical modelling

• Lossy transformations (DiscreteCosineTransform, FourierTransform)

Specific Algorithms

Please add new algorithms to the list below and detailed descriptions of them as possible.

• ShannonFanoEncoding

• HuffmanEncoding

• ArithmeticEncoding

• RunLengthEncoding (hey, don't laugh :l)

• LempelZiv, LempelZivWelch, variants

• BurrowsWheelerTransformation

Problems of Interest

Write software to do any of the above might be good.

comp.compression runs a data compression challenge (well, a poster does) - You have to compress a file with a million completely random digits to below its original size, including the size of your compressor and decompressor (not both pieces of software at once I would think). He was offering a cash prize - I'm not sure if the contest is still going but the challenge is interesting nonetheless. I believe he grabbed said numbers from http://www.random.org, although the website was not up at the time of this writing.