Hydrogen - advanced drum machine for linux/ windows / MacOSX

                                                                                            
                                                                                           Hydrogen is an advanced drum machine for GNU/Linux.

It's main goal is to bring professional yet simple and intuitive 

pattern-based drum programming.

General

• Very user-friendly, modular, fast and intuitive graphical interface based on QT 4.
• Sample-based stereo audio engine, with import of sound samples in .wav, .au and .aiff formats.
• Support of samples in compressed FLAC file.

Sequencer and mixer

• Pattern-based sequencer, with unlimited number of patterns and ability to chain patterns into a song.
• Up to 192 ticks per pattern with individual level per event and variable pattern length.
• Unlimited instrument tracks with volume, mute, solo, pan capabilities.
• Multi layer support for instruments (up to 16 samples for each instrument).
• Sample Editor, with basic cut and loop functions. (NEW)
• Time-stretch and pitch functions via rubberband cli. Require the rubberband-cli package.(NEW) 
• Play-lists with scripting function. (NEW)
• Advanced tab-tempo. (NEW)
• Director Window with a visual metronome and song position tags. (NEW)
• Time-line with variable tempo. (NEW)
• Single and stacked pattern mode. (NEW)
• Export/Import single patterns into song projects. (NEW)
• Midi learning via Shift+MouseClick on many gui-cotrollers combined with a midi settings editor. (NEW)  
• Ability to import/export song files.
• Unique human velocity, human time, pitch and swing functions.
• Multiple patterns playing at once.

Other

• JACK, ALSA, PortAudio and OSS audio drivers.
• ALSA MIDI and PortMidi input with assignable midi-in channel (1..16, ALL).
• Import/export of drumkits.
• Export song to wav, aiff, flac or ogg file.
• Export song to midi file.
• 
  

More info : http://www.hydrogen-music.org/hcms/