Pipe harmonixset beat txt files through drum_machine to listen to a clicktrack.

The file format drum_machine supports are the beat annotations here: harmonixset/datasets/beats_and_downbeats

The clicktrack is generated using libmetro. The beat txt files are parsed using a handwritten tokenizer/lexer and parser, based on this tutorial. drum_machine is fuzz tested with the entire harmonixset dataset as a corpus, and fuzzing is done with go-fuzz (tutorial). Run fuzz test with ./fuzz_test.sh.

Mapping harmonix to libmetro

libmetro provides the following constructs:

• beats are represented with note objects, which are wrappers around a vector of floats generated from Stk. libmetro is more flexible but the C wrapper and use in drum_machine are limited to the MIDI Drum instrument, and 2 'timbres' of beats
• bars are represented with measure objects, which are collections of a sequence of notes (can be padded with silence)
• the tempo of the song is configured on the metronome object, which can register a sequence of measures to loop through

Although the result is not mind-blowingly exciting given the tempo and beat structure of pop songs is stable, drum_machine still a fun combination of several projects.

Compile

Getting drum_machine built is not straightforward. You have to statically compile and install several C++ libraries from scratch. They must be compiled statically Go + cgo doesn't care about your configured dynamic library paths.

• https://github.com/andrewrk/libsoundio

After ensuring you have the correct dependencies (I've tested it only on Linux with ALSA, pulseaudio, and JACK libraries installed):

libsoundio $ mkdir -p build && cd build && cmake .. && make && sudo make install

• https://github.com/thestk/stk

I suggest you copy rawwaves to ~/rawwaves and compile this way:

stk $ autoconf
stk $ ./configure
stk $ ./configure RAWWAVE_PATH='$(HOME)/rawwaves/' BUILD_STATIC='yes'
stk $ cd src && make && sudo make install

# manually install the .a file, it's not in the makefile i believe
stk $ sudo cp libstk.a /usr/local/lib/libstk.a

• https://github.com/sevagh/libmetro

Libmetro is a C++ library but it has a minimal C wrapper to work with cgo.

libmetro $ mkdir -p build && cd build && cmake .. -DBUILD_STATIC=ON && make && sudo make install

Finally, compile this project:

drum_machine $ go build .

cgo configuration is:

// #cgo LDFLAGS: /usr/local/lib/libmetro.a /usr/local/lib64/libsoundio.a /usr/local/lib/libstk.a -lstdc++ -lasound -lpulse -ljack -lm
// #include <libmetro/cmetro.h>
import "C"