[theora-dev] What sort of math i required?

Ralph Giles giles at xiph.org
Sat Dec 6 10:27:32 PST 2003

On Sat, Dec 06, 2003 at 05:24:16PM -0000, erivy7302 at sneakemail.com wrote:

> Keep up the good work! The file sizes of Theora's output is amazing!

Glad you like it.

> I have just joined the list, and would like to contribute to the
> Theora/Vorbis project on the mathematics side, but I don't know what is
> required.

Timothy (derf) would be a better one to answer this; my training is in physics. It's all terribly 
applied and half-engineering of course.

Yes, the MDCT is a big part of both Theora and Vorbis. Information theory is the basis of all 
compression technology so you should be familiar with that as well. Linear algebra is a useful way 
of thinking about what can be done and how to do it. Pretty much all compression technology 
amounts to 'transform the data to concentrate non-randomness, then efficiently entropy-code that'. 
For lossy codecs like Theora and Vorbis, the transformation step isn't completely reversible in a 
clever way so that you don't store information that's perceptually difficult to notice.

Other helpful things are anything to do with signal processing and spectral theory, Green's 
functions. Wavelets too, although they're not currently used in the vorbis or theora designs. And 
general applied scientific and computing maths courses can be good. (Depending on the curriculum; 
they can also be really dumb.)

Hope that's of some help,
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