ShiftBud is a generative MIDI sequencer built around a 16-bit Turing-style shift register. The register rotates and mutates on each step. Its current value is converted either to a scale-based note or to a MIDI CC value, producing evolving phrases from a compact set of controls.
The app is available as a standalone instrument utility and as an AUv3 MIDI processor. Standalone mode can audition note output with an optional SoundFont sampler; the generated MIDI remains available for external routing.
The register is 16 bits wide. On every step it rotates right, then changes its highest bit according to Bias. With bias at or above 50%, the top bit is set probabilistically; below 50%, it is toggled probabilistically. Length controls the phrase length. At bias 0 or 1, the register completes a full loop after the configured length.
The register value is mapped across the full 0–65535 range. In Note mode the result becomes a scale degree in the selected key, scale, and octave range. In CC mode it becomes a controller value within the configured minimum and maximum CC values.
The main view exposes the register display, the current pattern, rate, key, scale, octave range, and the pattern strip. The register/bit view makes mutation visible as the phrase runs. Use the Settings button for trigger mode, MIDI channels, randomisation, CC output, and port controls.
Beat Sync as the trigger mode.Rate, Length, Bias, and the desired Note or CC mode.Beat-sync steps advance only while transport is playing. The grid is tempo-locked. Relocation, pattern changes, and a mode switch flush the current generated note and restart the register at the authoritative beat.
Choose MIDI Trigger when an external keyboard, pad, or sequencer should advance the register. Each incoming note-on on MIDI In Channel advances the register and fires the next output at the input event's exact beat. Quantize MIDI Trigger can snap the gate or CC-ramp anchor to the rate grid while retaining the live onset.
Enable Hold MIDI Trigger to keep the generated note sounding until the input note is released. New triggers are monophonic: the previous generated note is released before the new one starts. Transport play state does not gate MIDI-trigger mode.
In Note mode, Velocity, Velocity Random, Velocity Min, Velocity Max, Gate, and Gate Random shape the generated notes. A gate follows the pattern's rate and can be varied between the configured limits.
In CC mode, each register step emits a CC value on the configured CC number and MIDI CC channel. CC Min, CC Max, and CC Ramp define the range and the time over which a change is spread. A zero-distance ramp sends one value at the start rather than dividing by zero.
ShiftBud emits notes and CC messages on one MIDI cable. Configure MIDI Out Channel, MIDI CC Out Channel, and the CC number in Settings. The default pattern selector is Patterns CC# CC 10; its one-based value selects a pattern.
Incoming note triggers use MIDI In Channel. BrainBud program change 69 synchronizes key and scale from shared BrainBud settings. BrainBud Universal MIDI Channel accepts that message on any channel when enabled.
Press MIDI Panic to release generated notes and clear held trigger state.
Standalone Settings provides BPM, Ableton Link, MIDI In/Out port switches, and an optional SoundFont sampler. Enable the sampler to audition Note mode locally; use its Volume and Preset controls to choose the sound. CC mode has no local pitched sound and should be routed to a receiving device.
Load ShiftBud's AUv3 extension in a host with MIDI processing support. The host supplies tempo and transport for Beat Sync, while MIDI Trigger mode responds to incoming note events. AU parameters expose the pattern and register controls, and the plugin saves its full state with the host, including compatibility with older saved states.
Settings covers trigger mode, MIDI channels, pattern-selection CC, Note/CC mode, rate, length, bias, CC number and limits, CC ramp, velocity/gate variation, quantized MIDI triggers, hold behavior, key/scale, and octave range. The standalone screen additionally contains tempo, Link, sampler, port, and panic controls.
Use a moderate bias and a short length for a visibly repeating motif. Move bias toward the middle for more mutation, then lengthen the register for slower evolution. Beat Sync is useful for clocked patterns; MIDI Trigger is useful for expressive, keyboard-driven phrases. In CC mode start with a narrow range and a longer ramp, then widen the range for larger modulation sweeps.
No notes: Confirm Beat Sync is playing, or send note-ons on the configured input channel in MIDI Trigger mode. Check that Note mode is selected and that the octave range is valid.
No CC movement: Select CC mode, verify the CC number and CC output channel, and connect a destination that listens to the same MIDI cable/port.
Trigger feels late: Quantize MIDI Trigger affects the gate or ramp anchor, not the onset. Disable it for fully immediate phrasing.
A held note will not stop: Release the source note, then press MIDI Panic. Stopping the transport also flushes generated notes.
Pattern changes are ignored: Send the configured Patterns CC# with a one-based pattern value and check the input channel.
AUv3 state or tempo is wrong: Confirm the host is supplying transport/tempo and reload the saved preset. The AUv3 exposes the same shared parameter projection as the standalone app.