[sdiy] Reverse engineer an EPROM encoding?

[MTG]

Yes, that's kind of what this RFC3190 thing is ... chord/step just like 
u-law except different precision, if you will.  I will have to try a few 
other variations on that theme, then maybe looked at fixed point.

On 10/16/2013 12:02 PM, Tom Wiltshire wrote:
> Isn't Mu-law quite likely? Have you tried that? It was widely used for 8-bit samples, so it'd have been current when people moved up to 12-bit.
> According to this Wikipedia article, there's an "A law" variant too - same idea, different curve.
>
> http://en.wikipedia.org/wiki/Μ-law_algorithm
>
> (Compare the image at the bottom of the page with your R100_first_ramp.jpg)
>
> Either way, you're just hunting for a compensation curve. Cheater's idea of deriving it by experiment isn't too far out - it might be doable with sufficient accuracy.
>
> I can see real benefits to be had from such an encoding on a drum sample system, since drum hits typically have a short loud peak, followed by a longer body of sound at a much reduced (and reducing) amplitude. With a limited 12-bit resolution, that'd mean that most of your signal will actually be only 8 or 10 bit. Anything you can do to mitigate against that is going to be a plus.
>
> T.