This patch implements better USB MIDI handling, including listening for
detach, and handling the case where it's connected while the activity is
active.
This is a FIR filter with NEON speedup. The NEON version has been tested
for accuracy against the scalar one, and there is simple benchmarking
code in place as well.
Fixes various crashes, by (a) disabling the stats gathering thread and
(b) only trying to open a USB device if it identifies itself as a MIDI
keyboard. Disabling stats gathering should improve responsiveness and
improve battery consumption as well.
The crash in the stats gathering thread was a race on destruction, where
the audio thread set the stats_ringbuffer to NULL, but the Java thread
continued to try to read from it. This could be made more robust.
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).
On API 17+ (JellyBean MR1), get the buffer size and sample rate from the
platform, and use that, rather than hardcoding the defaults. We're still
using an internal buffer size (N) hardcoded to 64, so the amount of
computation per callback is not as consistent as it would be if that
were more flexible.
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