OT: grep by sound and grep by image

[Hiisi]

Hi, list!
Sorry if this thread interrupts the hottest discussions about gnome3
and systemd. I'm just curious.
There's a visgrep utility [1] that allows one to find images inside of
images. I wonder is there anything similar to google image search
where one could provide a pattern image and search for similar images
(i.e. not the exact occurrences of the pattern, but similar to it with
a desired accuracy)? Anything of the sort for sound patterns?
It doesn't seem like a pure fantasy. The program might analyse some
kind of spectrum of the pattern and compare it to its database. The
latter could be updated once per week or manually (by calling
updateimgdb script).
Any thoughts?
REFERENCES
1. yum info xautomation
2. http://www.google.com/imghp?hl=en&tab=wi
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Hiisi.
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