This patch implements nonlinear distortion in the resonant ladder
filter. It's based on the differential equations in the Huovilainen '04
DAFx paper, but using matrix exponential to compute the evolution of the
state variables. The implementation is scalar (and calls into sqrtf),
but designed to be implemented in very efficient SIMD.
This version was published to Play Store as 0.91.
Train patch didn't render right. Should investigate further, but in
the meantime swap out one that does. Also narrow filter range,
increase touch count to 10, and fix pitch env for L4 != 50 case
(take-off patch).
The "com.google" namespace is reserved for official releases, so
renaming to "com.levien".
Also small tweaking to piano2.xml to clean it up for release (arguably
should have been separate commit, but oh well).
Add a button to capture raw start and end callback time (just putting it
in a text buffer so it can be copied), which is useful for making plots.
Also a bunch of commented out code to provoke priority inversion or
sudden increases in load (which exercises the governor), again for the
purpose of probing performance and making plots.
The android_glue unit now collects timestamp stats and reports them up
through a ring buffer to the app. The app currently just displays a raw
line in a text view, but we'll expand that out to smarter aggregation.
This change adds a (single) resonant filter to the C++ synth unit, and
wires up both USB MIDI and on-screen controls for cutoff and resonance.
Also fixes a bug in KnobView which caused the knob value to jump around.
This patch wires up pressure sensitivity from the touchscreen. It also
adds simple USB Host mode for MIDI keyboards (tested on M-Audio KeyRig 49
and Akai MPK mini). Finally, it cleans up a bit.
The USB listening thread should be moved out of the activity and into a
service (there can be problems on multiple plug and unplug). But this
should be good enough to play with.
Raph Levien
Bryan Klimt