xtc/docs/USER_MANUAL.md

xtc user manual (0.1.0 development build)

xtc is a bounded Linux music-making prototype. Start with a copy of an important project and keep backups of its WAV media. Supported limits and unfinished areas are listed in KNOWN_LIMITATIONS.md; no production/device qualification is implied.

Build or install

Follow BUILD.md and LINUX.md. Core: make all test; GUI: make gui, then ./build/xtc. Use an existing JACK-compatible server and reconnect with F6. Connect midi_in to a controller, input to mono capture and output / output_right to left/right playback using your JACK routing application. No server, physical routing or system configuration is changed automatically. xtc --version, xtc --help and xtc --diagnose need no display/server.

For a source install stage with make install-gui DESTDIR="$PWD/build/stage" PREFIX=/usr, inspect the stage, and use your normal deployment process. A user prefix is supported (for example an absolute path to your .local folder). make uninstall with the same DESTDIR/PREFIX removes only that version's known files. See LINUX.md for package extraction, dependencies and removal. Never use a release built for a different system ABI without rebuilding/testing it.

Make a short project

1. New/Open starts in Sequencer. Add track; use F2 to name it.
2. Add MIDI clip, select it and open Piano roll (Ctrl+4). Left-click to draw notes, drag to move, drag a right edge to resize, Delete/right-click to remove.
3. Alternatively Import WAV (Ctrl+I). It creates/routes an Audio clips source; supported WAV formats and preload limits are in AUDIO_FILES.md.
4. Drag clips to arrange them and edges to trim. View/Snap sets the timeline grid; +/- zoom buttons and scrollbars navigate. Ctrl+D duplicates a clip after its end, retaining its complete source. F2 names clips; right-click offers duplicate/rename/delete. Alt+Up/Down with timeline focus reorders tracks.
5. Play/F5 starts; Pause/F7 or Stop/F8 leaves the position for resuming. Home returns to start while stopped (or stops first); click the ruler to seek. Recording uses Stop, not Pause. F9 Panic releases the instrument.
6. Mixer (Ctrl+2) offers track gain/pan/mute/solo and Gain/Pan automation lanes. Click to add points, right-click to remove. CONTROL.md explains timing and live CC7 volume, CC10 pan and CC64 sustain.
7. Save (Ctrl+S), close, reopen and continue editing. Ctrl+Z undoes and Ctrl+Shift+Z/Ctrl+Y redoes. New/Open resets history after unsaved-change handling.

Modular Graph (Ctrl+3) exposes routing. Drag output to input to connect, select a wire/node and Delete to remove; cycles and invalid ports are rejected. Keep an Output route for playback. GUI changes show queued/active graph status. Graph positions are session-only; music/routing/automation are saved. Edits that prepare new plans stop playback; disk/compilation may pause the GUI, never run in audio.

Record and retain media

Choose a project folder and save the project there first. Record/Shift+F5 asks for an unused WAV path. Stop finalizes the take and inserts it. Existing destinations are protected, including a file created while recording. Undo/removing a take removes its reference, never the recorded file. Imported external files are also never deleted. WAVs inside the save folder become relative references; move the folder and media together. Save As preserves the same source media, not a copy.

On write failure the GUI reports a retained path. Keep it and recover complete frames to a different, unused destination:

xtc-check --recover-recording take.wav.tmp.XXXXXX recovered.wav

Only xtc's canonical float32 mono temporary format is salvaged. Incomplete trailing frames are omitted. The source is retained. Import/relink the recovered WAV. Missing/unreadable media is silent and reported; select the clip and use File/ Relink selected audio. See RECOVERY.md for interruption, disk-full and power-loss limits. Close/project operations are refused while recording; finish the take first.

Trusted effects and sources

File/Load LADSPA plugin lists compatible descriptor indices from the chosen .so. Loading executes native code. Select a documented compatible mono plugin, connect its graph ports, then use Edit/Selected plugin control. Edit/Selected plugin automation adds/removes tick-based linear or step points. Control names/ranges appear in the dialogs. Module identity/control values/lanes save with the project; module binaries and DSP history do not. The initial amp/inverter/sine set and unsupported layouts are listed in PLUGIN_HOSTING.md. Missing plugins reject GUI Open with identity/path information and preserve the saved/current documents. Restore the compatible module at that path and retry. Plugins are not sandboxed.

Diagnose a problem

Run xtc-check --diagnose and capture the version, architecture, compiled features, GUI error text and steps to reproduce. xtc-check --validate song.xtc checks metadata without opening plugins/media; it does not certify playback resources. Check JACK routing, sample rate/format and xrun/process status in the GUI. After server loss/rate change stop/reconnect and retry. Keep the original project, media and retained temporary files before recovery attempts.

A native plugin can crash/hang the process. There is no crash-isolation guarantee. Use the operating system's core-dump/debugger tools if available; xtc does not install signal handlers, change core limits or upload crash reports. Debugger/ core files may contain media paths and audio memory; share only what you intend. Report bugs following MAINTENANCE.md, including whether the issue reproduces without plugins. Physical listening and independent human install/usability acceptance remain pending.

MIDI composition

In Piano roll, use the Notes menu for grid (including triplets), channel/pitch filters, velocity/channel, quantization, transposition and pattern repetition. Click selects a single note; Ctrl+A selects all filtered notes. Ctrl+D repeats that selection at a chosen spacing within the existing clip source. Up/Down transposes by a semitone. Commands are undoable through the main Edit menu. See MIDI.md for shortcuts, timing and limits.