How does it all mathematically work?

[Endless Summer]

Can someone point me to a website that goes over in detail the mathematics of the different codecs, compression, dubbing music. e.t.c.

[khp]

you should visit http://www.videocoding.de/ home of the xvid codec, it's an open source mpeg-4 codec.

Most high compression video codecs rely on DCT and iDCT as the most basic compression and decompression method. Do a search for idct with any popular search engine, and you will find all the math you could possibly want.