Add random 'tube' model
It's broken and has only a very fleeting association with anything that
would be a tube, but I'm committing it just as an example and 'something
like this'. I'm pretty sure I'm doing very wrong things with the FIR
filter, but it works (modulo that random multiplier hack) with at least
one amplifier impulse file (converted to raw format).
And when I say "works", I mean "makes something that sounds like
guitar". I'm not sure the sound actually matches what it should sound
like, and how much that FIR thing really matters.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
