Sequetron is a MIDI processing system for converting any MIDI-based
source, such as a music keyboard, drum pads etc., into a live multi-track
recording & playback system. It intercepts MIDI messages from the
input device & interprets them using a special command syntax to
dynamically alter its behaviour. This provides the musician with a rich
& extendible set of commands for switching between live playing,
recording & control, all from the same
ever needing to touch the computer keyboard or mouse. This reduces
distractions to creativity & inspiration normally encountered when
using musical instruments with computers.
The command set includes sequencer-like functions such as recording,
playback, looping, adjusting MIDI attributes etc., but the operation is
fundamentally different from conventional programs which dedicate specific
music keys to mimic windows control functions. Sequetron's command syntax
enables the same
music keys to perform multiple functions and,
together with a flexible mapping system, allows a practical set of
controls even on size-limited devices such as single-octave keyboards and
drum pads etc.
This summary uses a keyboard to demonstrate the operation, but any device
capable of generating MIDI note events can be used, including drum pads,
MIDI controllers, MIDI guitars etc. The term key-press
a MIDI note-on event from any of these devices.
The default action is to pass all key-presses straight through to the
output device; this is called live play
mode. To do anything
else requires a special sequence of key-presses known as a command
. Its syntax is designed to be logical & consistent for
ease of learning, at the same time providing a rich & extendible
command set using as few key-presses as possible. All steps of the command
are triggered by note-on events so keys do not have to be
released before pressing the next. The command sequence
terminates automatically when sufficient key-presses have occurred so no
additional 'enter' key-press is required.
The 128 possible MIDI key-presses are first mapped to functions according
to the user's preference & playing style. These functions are
mode-dependent, but modes can overlap for convenience or to use fewer
keys/notes on the instrument.
In live play
mode, the majority of key-presses are typically
mapped to the 'live play' function, so the instrument plays as normal.
This diagram shows an example of two octaves mapped for this mode; the
playable keys are labelled 'p'.
A command sequence
is initiated when the key corresponding to
the 'command' function is pressed, shown above mapped onto the left-most
'C' key and labelled 'cmd'. This causes a switch to command
mode, shown below, where the same keys now behave differently.
Subsequent key-presses are now interpreted as sequence-select functions
(Sequetron uses the term 'sequence' instead of 'track', so they are
labelled above as 'seq 1', 'seq 2' etc.) and/or a specific command. The
optional seq-select functions act as toggles and can be set/reset in any
order, but once a key corresponding to a command is pressed, the selection
& command are committed and the mode terminates.
If the command requires no further data, it is queued for action on the
selected sequences, and the system returns to live play
otherwise it switches to value
mode where subsequent key-presses
are now interpreted as qualifiers for the command.
e.g.1. a change-tempo command expects a beats-per-minute value, so the key
functions change to numbers.
e.g.2. a pitch command expects a pitch offset value, so the key functions
change to +/- semi-tone offsets relative to the original pitch.
When the correct number of values has been received, the command &
values are queued for action on the selected sequences, and the system
returns to live play
e.g.3. a record command expects recordable notes and controls for stopping
and/or immediately playing back the recording.
Keys labelled 'r' are recordable; other functions control how the
recording is to be stopped. Functions available include a simple stop (for
manual playback later), stop & playback immediately, stop &
playback automatically after a specific time, etc. The system returns
automatically to live play
mode when the recording has stopped.
At any stage, the 'esc' function can be pressed to abort the command and
return immediately to live play
The musician can play the instrument live, whilst switching in & out
of command mode to control the multi-track recorder with minimal
These videos show the general recording
technique in practice, and these show Sequetron's versatility with
different MIDI devices: miniature
(Yamaha QY-100), drum
(Korg padKontrol & Yamaha DD14).