Qtractor An Audio/MIDI multi-track sequencer

[Intro] [Screenshots] [Features] [Requirements] [Downloads] [CVS] [Installation] [Configuration] [Bugs] [Support] [Acknowledgments]

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 and native VSTi plug-in support.
• Unlimited number of plug-ins per track or bus.
• Plug-in presets, programs and chunk/configurations support.
• Audio/MIDI clip fade-in/out (linear, quadratic, cubic).
• Audio/MIDI clip gain/volume, normalize, export.
• 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.
• MIDI clip editor (matrix/piano roll).
• MIDI instrument definitions (a-la Cakewalk(tm)).
• MIDI controller mapping (mixer).
• JACK transport sync master.
• 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://www.qtsoftware.com/qt/
• 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/

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 CVS repository. However there has been several so called pre-releases that might be representative of the project's shallowed milestones.

Latest release

2009-06-04 - The Flaunty Demoness.
qtractor-0.4.2.tar.gz

• The MIDI clip editor (piano-roll/matrix editor), the main track view as well, have been subject to usability fixing, the most notable avoids clearing current selection as much as possible when updating view contents (eg. changing zoom levels does not reset current selection anymore).
• MIDI tracks channel bank/program and controller stuff are now only issued when the respective bus connections have changed, seldom on every playback start.
• MIDI controller mapping infrastructure, with file based configuration management (see View/Controllers...), is now in place, following an original contribution from gizzmo aka Mathias Krause.
• Plugin chain buffer reset on playback start/stop is not guarded by a momentary plugin de/activation anymore.
• Clip export may now be applied to multiple clips, sharing common refactored code and same semantics as merging of current selected clips.
• Improved, may be just fixed yet again, audio track export synchronization and reliability.
• Clip merge is now featured both for audio and MIDI tracks (see Edit/Clip/Merge...).
• Improved, or better said, fixed (again) the precision of multi-clip final positioning as result of drag/move and paste operations in main track view (as in bug #2741611).
• MIDI track program number is now listed in 1-128 range, in an attempt to be consistent with corresponding MIDI track dialog drop-down list.
• MIDI editor snap grid lines get slight different color then regular beat divisions.
• Reset local tempo map cursor on newer MIDI file imports in a tentative to fix incidental but random crashes.

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

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 couple of files:

• prefix/bin/qtractor
• prefix/share/pixmaps/qtractor.png
• prefix/share/applications/qtractor.desktop

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 still, after all this is early 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.

Acknowledgments

Qtractor user manual has 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.

This project has also a freshmeat.net entry.

Enjoy,

rncbc aka Rui Nuno Capela
rncbc at rncbc dot org