[jcelerier]

MIDI effects, loopers and MIDI sync.

Depends on

Merge these first, then bump the submodules here to their merged commits:

• Pitch bend upscale and whole sysex across MIDI 1 and MIDI 2 celtera/libremidi#268
• MIDI: sysex to the graph, removed devices, latency, loop WAV writer libossia#965
• MIDI objects, list / matrix / mask controls, MIDI batching and sysex in the ossia binding celtera/avendish#225
• Loopers, MIDI filter and MIDI sync pages score-docs#105

What it adds

• Loopers: the audio Looper rebuilt on a shared transport (layers with undo / redo / erase / mute, feedback, extend, capture, latency compensation, follow tempo, reverse, x1/4-x4 speed, per-cycle comping, restart in phase), and a new MIDI looper (merge / replace overdubs, controllers per key, held notes, grace, quantize on playback, transpose, MIDI layers view). Record on a loop overdubs it, as on hardware loopers. Takes sent or dragged to the timeline play with the looper's Follow tempo (Off: unstretched). Takes are written as loop WAV / SMF files carrying their tempo, and sent or dragged to the timeline as one box with a looping slot per file.
• MIDI effects: Arpeggiator (7 new patterns, gate, swing, accents, velocity decay, retrigger, latch, pressure, seed), Chord (43 chords, harmonizer, inversion, voice chance / velocity, strum, learned memory, MPE), Midi scale (direction, remap matrix, fold, range), Midi quantify (gate, trigger on release, decay, release velocity), LFO one shot. Ten new avendish MIDI processes registered, MIDI subcategories in the library.
• MIDI Sync Out: free clock with tap tempo, nudge, clock rate, clock offset; one sender; Start, seeks and loops send Stop / Song Position / Continue with the Song Position on the receiver's next 16th; first clock with Start; MTC fixes.
• Widgets: value list, note matrix, channel mask; long enums as drop-downs, range slider values, text field sizes.
• Binding: object-to-UI messages reach every view without allocating; UI-to-object values and messages are made and freed on the main thread via the GC queue; one-shot UI updates retried when the queue is full; stop() deferred one tick so the last notes end.
• Engine: no crash closing a document whose processes read a MIDI device; one process per dropped .mid (master made two); MIDI device input keeps sysex; driver latency in the execution state.

Behaviour changes from master

• Midi filter's Channel keeps the selected channel (master dropped it): scores that set it filter the other way.
• Midi scale custom masks count from Base; "custom" passes every note (master dropped them).
• Chord, Arpeggiator, Midi quantify and the MIDI objects end their notes when the process ends.
• Audio Looper: overdubbing an empty loop records it; overdubs are layers; at most Channels (2) and Max length (60 s); a take file is written per recording; late stop within 120 ms of a grid point. Quantif is now Quantize: its Whole becomes 1 bar; other note values are now real note lengths in every signature (a 4th in 3/4 is a quarter, not a third of the bar).
• MIDI Sync Out / In: see above; 29.97 and 30 fps timing fixed.

New ports are appended; uuids, port order and saved enum values of existing objects are unchanged.

Release notes (for ossia-score.appdata.xml)

New features

• loopers: the Looper is rebuilt and joined by a MIDI looper: layers you can undo, redo, erase, mute and solo; takes kept for comping; overdubs that extend the loop; reverse and tape speeds; capture of what was just played; loops that follow the tempo; a Switches tab for footswitches; and a Quantize that waits for the loop's restart, N bars, triplets or a time in seconds. Every recording is written as a loop WAV or MIDI file, which can be sent or dragged to the timeline as a box with a looping clip per layer.
• midi: new objects: Midi transform, Midi CC snapshot, Midi value shaper, Midi dispatcher, Midi MPE, Midi sustain, Midi delay, Midi random sequencer (Turing Machine and Marbles), Midi progression player (194 progressions in Roman numerals) and Midi life (a Game of Life sequencer). Every MIDI object comes with presets.
• midi: Chord gains a harmonizer, 43 chords, inversions, per-voice chance and velocity, strumming, learned chords and MPE output; Arpeggiator gains seven patterns, gate, swing, accents, velocity decay, retrigger, latch, pressure and a seed; Midi scale remaps degrees; Midi quantify gains gate, trigger on release and decay; LFO gains a one-shot mode.
• midi: Midi filter selects by lists of types, channels, notes, controllers and values, remaps them, and sends what it rejects to its own outlet; Midi scaler outputs retuned MIDI, per-note pitch bend or MTS.
• midi sync: MIDI Sync Out has a free-running clock with tap tempo, nudge, clock rate and clock offset; MIDI Sync In decodes full-frame timecode and sends a divided, shifted and delayed clock.
• avnd API: list, note-matrix and channel-mask controls, drag payloads, sending files to the timeline, and alignment for layouts.

Improvements

• midi: MIDI objects end their notes when their process ends, and MIDI sent before a loop point or a stop that falls inside a buffer is no longer lost.
• midi: system-exclusive messages from MIDI devices reach processes whole, so full-frame timecode now drives MIDI Sync In.
• midi sync: after a seek or a loop, MIDI Sync Out sends a Song Position on the receiving device's next 16th note and starts the clock there, at any clock rate; the first clock goes out with Start; 29.97 and 30 fps timecode is timed correctly, sent and received.
• midi: system-exclusive messages from a graph port reach VST2, VST3, CLAP and LV2 plug-ins, MIDI devices and scripts whole; the Scala tuning object's MTS output selects the tuning on every channel and can be sent again.
• midi: a MIDI file is placed by its beats, so a two-bar file is two bars whatever tempo it was saved at; dropping a MIDI file creates one process instead of two, and MIDI 1 pitch bend going through MIDI 2 keeps its centre.
• midi filter: the Channel control keeps the selected channel; it used to drop it, so scores that set it now filter the other way.
• midi scale: custom 0/1 masks count from the Base note instead of C, and choosing "custom" lets every note through instead of none.
• looper: scores made with the previous Looper keep their settings; overdubbing an empty loop now records it, overdubs are kept as layers, a loop holds at most its Channels (2) and Max length (60 s), recordings are written as files next to the score, the old Restart setting is now Start from, Takes is now Export, Loop is Mode, Quantif is Quantize (its Whole becomes 1 bar while shorter values keep their note value in every signature), Bars is Record bars; the Sync setting is gone; Record on a loop that holds something now overdubs it (Clear first to record anew).
• crashes: closing a score, or removing a MIDI device, while processes read a MIDI device no longer crashes.
• widgets: long lists of choices are drop-downs, range sliders show their values, and grids keep their size when laid out again.

Tests

Full build; 105 targeted test programs pass (avnd, fx, looper, preset loader with 263 preset fixtures in tests/fixtures/presets, midi, execution, graphics, protocol, nodes). UI checked in the running app (screenshots of the loopers, take boxes, MIDI layers).

🤖 Generated with Claude Code

https://claude.ai/code/session_01Qr9WkcUjEGCueg7eG1KxSr

[coveralls]

coverage: 50.888% (+1.7%) from 49.183% — feature/midi-effects into master