MbiraGen is a free semi-generative sequencer vst plugin that produces MIDI notes based on a sequence of up to 12 “melodies”. Each melody can have up to 4 variations which are selected round-robin. A Melody is a 5×4 grid where the vertical direction indicates note pitch and the horizontal direction indicates time.
Pitches are assigned based on a combination of settings: the tonic note, the scale, the mode, the interval assigned to the melody, and the individual scale degrees represented by the vertical positions in a melody.
In addition to the melody sequencer there is a velocity sequencer, controls for sync time, note length, velocity jitter, note length jitter, and 2 additional sequencers that can apply variations to the melodies as they are being played. These variations provide the drift and randomness that keeps the pattern from feeling too repetitive.
Plugin targets VST2.4 on Windows. 32-bit and 64-bit versions available.