Small examples and use cases¶

The four ravet-examples entry points open an interactive native window on macOS with the default live-ui feature. Build with Rust and Xcode command-line tools, using the getting started prerequisites. The portable processors and explicit offline fixtures also build without live-ui.

cargo run -p ravet-examples --bin midi-synth --locked
cargo run -p ravet-examples --bin effect --locked
cargo run -p ravet-examples --bin mpe --locked
cargo run -p ravet-examples --bin midi2 --locked
cargo run -p ravet-examples --bin layout_workspace --locked

Each window includes tabs for all four examples. Click Audio / MIDI… in the native title bar to open the standard settings popup. Choose an output, active channel pairs, sample rate and buffer size, then press Start audio. The popup closes after a successful start; reopen it to stop or change settings. Devices are never opened merely by creating a window. Empty input/MIDI inventories hide their controls. Buffer labels show samples and nominal milliseconds; “Device default” leaves buffer negotiation to the backend. A requested fixed buffer is not a measured latency or callback-size guarantee.

Available audio inputs and their channel pairs appear in the same popup. The effect can process a selected input or quiet, rhythmic demo bursts. The synth generates its own audio; optional captured input does not alter its sound. Multiple MIDI inputs can be enabled together (at most 16 in these examples). No MIDI input is selected initially; the on-screen keyboard remains available. Stop audio before changing settings and refresh explicitly after device changes. Audio/MIDI selections are remembered between launches; unavailable devices remain unselected. The main Start/Stop button restarts with the current settings, opening the popup if no output is configured. Restore does not start audio automatically.

Subtractive MIDI synth¶

The portable processor has eight voices, sine/polyBLEP saw/polyBLEP square/triangle waveform selection, a resonant low-pass VCF and a VCA. One ADSR per voice drives both amplitude and filter excursion. The knobs support vertical dragging, Shift for finer pointer changes, arrow and Home/End/Page keys, numeric entry and double-click reset. Cutoff uses logarithmic knob travel. The shared web controls provide gesture ownership and snapshot refresh without feeding edits back to audio.

ADSR edits latch at the next note-on. Level, waveform, cutoff, resonance and filter amount affect held notes. Waveform changes retain oscillator phase but are not crossfaded. Filter coefficients are prepared on the UI thread into a fixed 256-step table; audio selects an entry from envelope/timbre position. Triangle can alias; there is no limiter or overload guarantee at high resonance. MIDI velocity scales the VCA and the mix scales by the eight-voice capacity.

Click and hold piano keys or use A W S E D F T G Y H U J K when the page background or piano widget has keyboard focus. The reusable two-octave keyboard spans C3–C5, with shorter black keys layered above adjacent white keys. Independent pointers play chords; dragging releases the previous key and starts the next. Focused piano keys also play with Space/Enter. Release, cancellation, opening settings or leaving the window releases held on-screen notes. All notes off clears queued notes at the next processing block. MIDI sustain, bend and the existing two-zone voice policy remain available.

This app is distinct from the existing Sine CLAP reference, which has its own fixed sine processor and host level control. The new subtractive processor does not yet have a plug-in export.

Stereo delay effect¶

The live effect uses the portable delay processor, built from RAVET's prepared fractional delay lines and sample-counted smoothers. Three knobs control delay time, feedback and wet/dry mix, with optional ping-pong cross-feedback and dry bypass. Demo mode plays tapered, staggered stereo tone bursts every 0.9 seconds, making the repeats audible without an input device. The Demo loop switch is in the effect panel. Turn it off to process the input device selected in Audio/MIDI settings; that popup lists device inputs and No input, without synthetic sources or files. With no input selected and Demo loop off, the effect receives silence.

Delay time glides over 20 ms, producing a brief pitch change during edits. Feedback, mix and ping-pong routing ramp over 5 ms. Stereo mode repeats each channel independently; ping-pong sends each delayed channel into the opposite feedback branch. Bypass immediately returns dry input while internal repeats continue. Reset clears the delay history and preserves requested controls. There is no limiter, tempo sync, preset persistence or new delay plug-in export. The portable processor accepts mono/stereo f32 at 8..192 kHz, up to 1,024 frames and 128 input events. Two f64 delay lines allocate only during preparation; processing, control changes and reset perform no heap operations. Nonfinite input samples become zero; ordinary finite input still requires output headroom.

Input channel pairs selected in settings are averaged into stereo; the stereo result is copied to each selected output pair. Unselected output channels are silenced; an odd final mono channel receives the stereo average. Input and output clocks use the existing clocked duplex adapter, including conversion when their default input rate and selected output rate differ.

The existing Gain plug-in remains a separate, simpler plug-in integration:

python3 scripts/bundle-clap.py --plugin gain --profile release
cargo run -p ravet-clap-smoke --locked -- 'target/clap/release/RAVET Gain.clap'

See getting started and native editor for its editor and recorded host limits. Plug-in I/O is configured by its host; the standalone settings popup is not added to host-owned embedded editors.

MPE performance¶

The MPE tab plays the subtractive synth. Its on-screen keyboard configures a lower zone with master channel 0 and two member channels, 1 and 2 (zero-based). Member bend defaults to ±48 semitones; master bend retains its receiver default. Select a member and adjust its bend, pressure and timbre knobs while holding a note. Pressure increases VCA amplitude by up to 50%; CC74 timbre adds up to 24 semitones of filter opening. A connected controller can negotiate zone/range settings through MIDI RPN messages. The voice table exposes expression and ADSR. The two-note on-screen limit is independent of the synth's eight-voice pool.

Native MIDI queues retain complete packets. This example consumes short MIDI messages at the next audio block; it does not map native timestamps to sample offsets. There are 256 packet slots per input and at most 64 polling attempts per processing block shared across up to 16 inputs. Full MIDI/control queues clear voices rather than leaving a dropped note-off stuck. No physical controller conformance or audio deadline is established by offline fixtures.

Resizable layout workspace¶

The workspace consumer uses measured native standalone content size, explicit constrained Rust grid tracks/spans and five ordinary labelled HTML panels. Narrow windows move the inspector below the editor; fonts and controls retain their normal sizes. The default Audio/MIDI popup remains enabled with truthful unavailable-device state, and this example opens no devices. Its explicit --fixture validates owned hidden windows and actual WebKit geometry across small/aspect-fitted and rapid resize requests.

cargo run -p ravet-examples --bin layout_workspace --locked -- --fixture

See the main owner, geometry policy and local document.

MIDI 2.0 packet inspector¶

The MIDI 2.0 tab provides editable group/channel/key, 16-bit velocity and 32-bit expression fields. Encode/decode displays exact UMP words and recovered fields, retaining up to 16 packets. It is a codec inspector: it opens no devices and does not synthesize MIDI 2.0, negotiate MIDI-CI/profiles or export a MIDI 2.0 plug-in. The settings popup explains this when opened from that tab. Native UMP delivery is a separate CoreMIDI UMP capability.

Offline fixtures and checks¶

Rendering and scripted traces require explicit flags:

cargo run -p ravet-examples --bin midi-synth --locked -- --render target/examples/synth-fixture.wav
cargo run -p ravet-examples --bin effect --locked -- --render target/examples/effect-fixture.wav
cargo run -p ravet-examples --bin mpe --locked -- --offline
cargo run -p ravet-examples --bin midi2 --locked -- --offline
cargo test -p ravet-examples --no-default-features --locked

The offline helper renders stereo PCM16 at 48 kHz in 256-frame blocks with at most 32 scheduled events and refuses file overwrite. Synth fixtures exercise note/pedal/release timing; effect fixtures check decaying ping-pong repeats and exact bypass offsets. Portable delay tests additionally check partition-independent automation, maximum delay, transactional event rejection, tail retention during bypass and zero heap actions. Scripted MPE prints independent member/master expression; MIDI 2.0 checks full-resolution timed UMP round trips. These fixtures do not open devices or windows.

On macOS, the hidden native UI fixture checks all tabs, title-bar popup activation, explicit opt-out, controls, fake channel/rate/buffer selection, note release and packet inspection. It writes screenshots and opens no actual devices:

cargo run -p ravet-examples --bin midi-synth --locked -- --ui-test target/examples-ui
cargo test -p ravet-examples --locked

The live UI owner and bounded audio adapter keep JSON, native ownership and coefficient preparation outside processing. A fixed 16-command queue carries prepared patches; coherent word snapshots carry meters/voices. The device adapter accepts f32 configurations with at most 64 channels, selected rates 8..192 kHz and prepared sub-blocks of at most 512 frames. Live changes and arrival-time MIDI are block-quantized. Native window/device integration remains a macOS prototype; broader platforms, devices, long sessions and deadlines need actual validation. See work status for evidence.

The example window locks its content aspect ratio to 900:780. A single 900×780 design canvas scales uniformly in both directions, including text, controls, panels and spacing. Resize events update the canvas immediately; the scale is not capped. All four tabs are checked at 720×624, 900×780 and 1080×936, plus wide/short and narrow/tall requests constrained to the same aspect ratio. The fixtures verify actual browser dimensions, control dimensions/positions and unclipped content. Voice details scroll inside their bounded monitor panel. Shared semantic palette tokens cover controls, settings and piano keys; Amber is the selected RAVET default, with charcoal/plum surfaces and amber emphasis. Disabled piano keys remain opaque.

Color preparation workspace¶

The color workspace consumes reusable Rust sRGB/linear-light image preparation through labelled opacity and white/amber controls. It retains ordinary window resizing and the default Audio/MIDI popup, with a hidden owned fixture and a portable JSON export. Pixel/profile limits and independent numeric validation are documented in the guide.

The complete SVG image workspace imports the outlined RAVET logo and authored gradient/arc/clip/opacity assets, prepares Rust pixels and presents labelled source/fit/size controls. --export creates no window; macOS native mode retains the standard Audio/MIDI settings popup.

The native_semantics tutorial shares one Rust custom-control model between actual WebKit visual content and an explicit native semantic companion, including checked geometry and guarded native intents. The standard Audio/MIDI settings popup remains enabled; native protocol evidence is separate from VoiceOver.

The local font fallback consumer runs as cargo run -p ravet-examples --bin font_fallback --features font-fallback --locked. Its --export mode is headless; --fixture owns a hidden macOS window and checks actual Rust-selected fonts, native resize, the default settings popup and cleanup.