Qtractor

Qtractor is an audio/MIDI multi-track sequencer application written in C++ with the Qt framework [1]. Target platform is Linux, where the Jack Audio Connection Kit (JACK) for audio [2] and the Advanced Linux Sound Architecture (ALSA) for MIDI [3] are the main infrastructures to evolve as a fairly-featured Linux desktop audio workstation GUI, specially dedicated to the personal home-studio. Features Multi-track audio and MIDI sequencing and recording. Developed on the Qt C++ application and UI framework [1]. Uses JACK [2] for audio and ALSA [3] sequencer for MIDI as multimedia infrastructures. Traditional multi-track tape recorder control paradigm. Audio file formats support: OGG (via libvorbis [6]), MP3 (via libmad [7], playback only), WAV, FLAC, AIFF and many, many more (via libsndfile [4]). Standard MIDI files support (format 0 and 1). Non-destructive, non-linear editing. Unlimited number of tracks per session/project. Unlimited number of overlapping clips per track. XML encoded session/project description files (SDI). Point-and-click, multi-select, drag-and-drop interaction (drag, move, drop, cut, copy, paste, paste-repeat, delete, split, merge). Unlimited undo/redo. Built-in mixer and monitor controls. Built-in connection patchbay control and persistence (a-la QjackCtl [18]). LADSPA [5], DSSI [11], native VST(2), VST3 [12], LV2 [13] and CLAP [20] plug-ins support. Unlimited number of plug-ins per track or bus. Plug-in presets, programs and chunk/configurations support, including native VST FXB/FXP file support. Unlimited audio/MIDI effect send/return inserts per track or bus. Loop-recording/takes. Audio/MIDI clip fade-in/out, cross-fade (linear, quadratic, cubic). Audio/MIDI clip gain/volume, normalize, export. Audio/MIDI track and plugin parameter automation (dynamic curves, sample&hold, linear and spline modes). Audio clip time-stretching (WSOLA-like or via librubberband [9]), pitch-shifting (via librubberband [9]) and seamless sample-rate conversion (via libsamplerate [8]). Audio/MIDI track export (mix-down, render, merge, freeze). Audio/MIDI metronome bar/beat clicks. Unlimited tempo/time-signature map. Unlimited location/bar markers. MIDI clip editor (matrix/piano roll). MIDI instrument definitions (a-la Cakewalk(tm) ( .ins) [19]); SoundFont ( .sf2) and MIDI Names XML ( .midnam) files also supported. MIDI controller mapping/learn/assignment (mixer and plug-in parameters). MIDI system exclusive (SysEx) setups. JACK transport sync master/slave. JACK session support. NSM (Non/New Session Management) support [15]. MMC control surface enabled. MIDI Clock, Song Position Pointer (SPP) support. Configurable PC-keyboard and MIDI controller shortcuts. Optional (opted-in at build time): libvorbis [6] (enc, file), Ogg Vorbis audio compression libmad [7], High-quality MPEG audio decoder libsamplerate [8], The secret rabbit code, C library for audio sample rate conversion librubberband [9], Rubber Band Audio Time Stretcher, an audio time-stretching and pitch-shifting library liblo [10], Lightweight OSC implementation (needed for DSSI GUI [11] and/or NSM support [15]) DSSI [11], An API for soft synth plugins with custom user interfaces VST SDK [12], Steinberg's Virtual Studio Technology (see README.VST(3)) LV2 [13], Audio Plugin Standard, the extensible successor of LADSPA liblilv [14], Lightweight LV2 host implementation stack CLAP [20], CLever Audio Plugin Qtractor is free, Linux Audio [16] open source free software. For bug reports, feature requests, discussion forums, mailing lists, or any other matter related to the development of this piece of software, please use the Sourceforge project page ( The (out)dated Qtractor quick start guide and user manual for version 0.5.x has been authored by Seth Kenlon & Klaatu. ( The older Qtractor user manual for version 0.3.0 and before, have been co-authored by James Laco Hines and Stephen Doonan. ( Qtractor logo/icon is an original work of Andy Fitzsimon, borrowed from the public dom