[music-dsp] SF's Acoustic Mirror format

[Steve Harris]

Thinking of reverse engineering...

I recently wrote a realtime convolver for linux, so I wanted to get all my
old Acoustic Mirror impulses back. I downloaded a few AM files from SF (I
was at work), and tried to work out what was in them.

It turns out that the audio data in there is obfuscated, I spend about a
day trying to unravel it, before it occured to me that I didn't even know
if /my/ impulses are in this format, or just saved as WAV's (I can't find
them so I don't know). It could just be how SF protect thier distributed
impulses.

I manged to work out how they were storing it, but getting the exact data
back would involve a lot of trial and error, and I don't think its worth
it. Thier encryption is pretty lame, if they'd thought about it a bit
harder they could have made it much harder to decode.

Still if anyone has a reason to decode the files, I can tell you how its
stored, just not the actual key they use (I have an aproximation of it).

- Steve

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