Failure
Under the heading of "stuff that didn't work", I'm stuffing my attempt at spline-based audio compression. The thought was to take advantage of large scale structure in audio data to losslessly compress it by fitting a spline to the data, and encoding the residual signal using standard techniques found in codecs like FLAC. Initial results were well short of encouraging, so onto the junk heap it goes. On the bright side, I did get some halfway decent spline fitting code out of it.
Here's what I completed before setting it aside. The code's a bit of a mess, since it was stopped mid-stream, but the spline code should be separable with a bit of effort. I was testing out a way of enabling/disabling exception handling in the library using #defines, but this turned out to be more trouble than it was worth. If I come back to it, that's definitely coming out, maintaining two error pathways is just a pain in the ass, with no real benefit.