[vorbis-dev] video compression using textured polygons?

Steve Underwood steveu at coppice.org
Sun Jan 7 04:26:02 PST 2001

"Kenneth C. Arnold" wrote:

> Chirplets? Can anyone go beyond the buzzword and tell me what's going
> on with them? Everything I've seen looks promising but isn't enough to
> write an actual implementation or even do something by hand with them.

In the Second World War the British got radar pulse power up to the point
where they had flashover in the waveguides (i.e the field exceeded the
breakdown voltage of the air). They pressurised the waveguides, but still had
flashover at the antenna. Then someone thought "Why make one damn great
narrow pulse? Why not smear the energy in time through a dispersive filter,
and use the reciprocal dispersive filter on receive? Lower peak energy - same
result". Suprisingly it took until the late 50's before guys a Bell Labs did
a proper mathematical analysis of the effects of chirping. By spreading a
pulse, in time, against an even noise background there is a substantial
signal processing gain, as well as a peak energy reduction. The same idea has
been used in sonar, and other things as well. Many echo locating bats chirp,
and obtain all the signal processing benefits a radar does - Mother Nature
has some major prior art!

Now take this idea, and mix it with wavelets. If you smear the energy, you
reduce the peaks, and thus the dynamic range. It sounds like it should have
some benefits in compression, but who knows.


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