Qtractor An Audio/MIDI multi-track sequencer

What's Qtractor ?

Qtractor is an Audio/MIDI multi-track sequencer application written in C++ with the Qt4 framework. Target platform is Linux, where the Jack Audio Connection Kit (JACK) for audio, and the Advanced Linux Sound Architecture (ALSA) for MIDI, are the main infrastructures to evolve as a fairly-featured Linux desktop audio workstation GUI, specially dedicated to the personal home-studio.

Qtractor is free, open-source software, distributed under the terms of the GNU General Public License (GPL) version 2 or later.

Project page: http://sourceforge.net/projects/qtractor

Weblog: http://www.rncbc.org

Screenshots

Click on image to see more screenshots...

Features

• Multi-track audio and MIDI sequencing and recording.
• Developed on pure Qt4 C++ application framework (no Qt3 nor KDE dependencies).
• Uses JACK for audio and ALSA sequencer for MIDI as multimedia infrastructures.
• Traditional multi-track tape recorder control paradigm.
• Audio file formats support: OGG (via libvorbis), MP3 (via libmad, playback only), WAV, FLAC, AIFF and many, many more (via libsndfile).
• 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).
• LADSPA, DSSI, native VSTi and LV2 plug-in support.
• Unlimited number of plug-ins per track or bus.
• Plug-in presets, programs and chunk/configurations support.
• Unlimited audio effect send/return inserts per track or bus.
• Loop-recording/takes.
• Audio/MIDI clip fade-in/out (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), pitch-shifting (via librubberband) and seamless sample-rate conversion (via libsamplerate).
• Audio/MIDI track export (mix-down, merge).
• 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));
  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.
• MMC control surface enabled.
• MIDI Song Position cueing support.
• Configurable keyboard shortcuts.

Requirements

The software requirements for build and runtime are listed as follows:

Mandatory:

• Qt 4 (core, gui, xml), C++ class library and tools for crossplatform development and internationalization
  http://qt-project.org/
• JACK Audio Connection Kit
  http://jackaudio.org/
• ALSA, Advanced Linux Sound Architecture
  http://www.alsa-project.org/
• libsndfile, C library for reading and writing files containing sampled sound
  http://www.mega-nerd.com/libsndfile/
• LADSPA, Linux Audio Developer's Simple Plugin API
  http://www.ladspa.org/

Optional (opted-in at build time):

• libvorbis (enc, file), Ogg Vorbis audio compression
  http://xiph.org/vorbis/
• libmad, High-quality MPEG audio decoder
  http://www.underbit.com/products/mad/
• libsamplerate, The secret rabbit code, C library for audio sample rate conversion
  http://www.mega-nerd.com/SRC/
• librubberband, Rubber Band Audio Time Stretcher,
  an audio time-stretching and pitch-shifting library
  http://breakfastquay.com/rubberband/
• liblo, Lightweight OSC implementation
  (needed for DSSI GUI support)
  http://liblo.sourceforge.net/
• DSSI, An API for soft synth plugins with custom user interfaces
  http://dssi.sourceforge.net/
• VST SDK, Steinberg's Virtual Studio Technology
  http://www.steinberg.net/
• LV2, Audio Plugin Standard, the extensible successor of LADSPA
  http://lv2plug.in/
• liblilv, Lightweight LV2 implementation stack
  http://drobilla.net/software/lilv/
  http://drobilla.net/software/suil/
  http://drobilla.net/software/sratom/
  http://drobilla.net/software/sord/
  http://drobilla.net/software/serd/

Downloads

Qtractor's still in some alpha stage of development, but already functional. The bleeding-edge development source tree is readily available from the sourceforge's public Subversion repository. However there has been several so called pre-releases that might be representative of the project's shallowed milestones.

Latest release

2013-03-19 - The India Romeo
qtractor-0.5.8.tar.gz

• Dropped old audio ramping spin-locks as its glitching reduction weren't that effective anymore.
• Audio bus and track gain may now be set for amplification again, from +0dB up to +6dB, while using the Mixer strip sliders/faders (an old function found missing ever since pre-TYOQA).
• Basic LV2 X11 UI support has been added through libSUIL but only really effective if plugins doesn't support the LV2 External UI extension in addition which takes precedence on any case.
• Improved precision tolerance on the Tempo Map / Markers dialog.
• Reinstated and fixed (old) warning and impending re-conversion on loading session files which the original sample-rate differs from current audio device engine (aka. JACK).
• LV2 Plugin State/Preset name discrimination fix (after a ticket by Jiri Prochaszka aka. Anchakor, thanks:)
• Linked/ref-counted audio clips must not overlap and now must have a buffer-size worth of a gap between each other.
• Something fishy has been detected in the SSE (not so) optimized code from SoundTouch's-inspired WSOLA time-stretching.
• Splitting clips apart is now easier than ever: a brand new entry enters the main menu scene: Edit/Split (Ctrl+Y) splits up clips according to current range/rectangular selection.
• Audio clip offsets are now properly corrected when time-stretching is applied via Shift/Ctrl+dragging any of the clip edges.
• One semi-colon typo was hiding proper descrimination of peak files used to draw distinct waveforms of time-stretched audio clips.
• Track automation curves are now also affected by Edit/Insert/Range commands.
• Finally, some visual feedback is shown while audio track export is running, in he form of a main status progress bar.
• New user option: save backup versions of existing session files.
• Default session directory now set to regular file's path on load.
• A convenient minimum slack duration has been fixed for MIDI SysEx messages.
• LV2 Time/position information is now asynchronously fed back into their parameter (control input) ports when designated.
• LV2 State is now properly restored for plugins inserted on buses, probably solving the Calf Fluidsynth SoundFont information missing on buses ticket, reported by Albert Graef, thanks.
• Fixed an immediate null pointer crash on creating a parentless new group while on the files organizer widget.
• Preparations for future Qt5 migration.

Previous and older pre-releases, including the change log, are also available here.

You can browse all files available for download, including binary packages, at Qtractor Files on SourceForge.net.

Installation

The installation procedure follows the standard for source distributions. Once under the extracted source directory:

./configure [--prefix=prefix]
make

and optionally as root:

make install

This procedure will end installing the following files:

• prefix/bin/qtractor
• prefix/share/applications/qtractor.desktop
• prefix/share/icons/hicolor/32x32/apps/qtractor.png
• prefix/share/locale/qtractor_*.qm

Just launch prefix/bin/qtractor and you're off (hopefully). Note that the default installation path prefix is /usr/local .

Configuration

Qtractor holds its settings and configuration state per user, in a file located as $HOME/.config/rncbc.org/Qtractor.conf. Normally, there's no need to edit this file, as it is recreated and rewritten everytime qtractor is run.

Bugs

Plenty, after all this is still alpha software ;).

Support

Qtractor is open source free software. For bug reports, feature requests, discussion forums, mailling lists, or any other matter related to the development of this piece of software, please use the Sourceforge project page.

You can also find timely and closer contact information on my personal web site.

Acknowledgements

A new Qtractor quick start guide and user manual has been updated for version 0.5.x by Seth Kenlon & Klaatu.

The older 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 domain openclipart.org gallery.

A special mention should also go to the translators of Qtractor, of course:

This project has also a freshmeat.net entry.

Enjoy,

rncbc aka Rui Nuno Capela
rncbc at rncbc dot org