Instrumental MIDI Sequencer designed to transpose prototypical features of traditional musical instruments to the realm of electronic music. The functional features of OCTOPUS were derived from stated requirements of a broad community of electronic musicians and strongly influenced by our own experience as performers and composers.

Extended information

The Octopus user interface features the following main visual groups:
- Left knobs: Each row has a dedicated left knob.
- Selector buttons: Each row has a dedicated selector button.
- Matrix: The arms of Octopus. Inspired by the legacy of chaser light step sequencers and designed to provide functionality much beyond that of its predecessors. For example, the matrix keys can be assigned note triggers, such that melodic structures can be tapped in, similar to keyboards or other instruments.
- Mutator buttons: Each row has a dedicated mutator button.
- Right knobs: Each row has a dedicated right knob.
- Circle: The head of Octopus. Inspired by the quint circle and designed to provide related functionality in the Page operating mode and otherwise. While projected to allow chord and transposition related capabilities, the range of
functions available for the circle in the initial release is under evaluation.

Each of the listed components takes on specific functions according to the
operation mode active at any point in time. The operation mode section provides more details on each of them.

This section provides an introduction to the concepts at the base of Octopus. In brief, the Octopus world consists of entities or objects, attributes that are associated with them, and functions that modify those objects or their attributes. The idea is to allow modifications of the objects in the most flexible manner and real time, which is done using an intuitive control model and the comprehensive Octopus user interface.

The master Octopus object is the GRID, which contains PAGES, each of them containing TRACKS, which are made up of STEPS. Each object is associated with attributes and functions that can be operated upon. Below is a more detailed overview of the object and their abstraction levels, their attributes and functions.

Octopus provides a total of 160 pages grouped in 16 banks of 10 pages each, making up the GRID. Visually a bank corresponds to one column of the matrix, hence a page corresponding to one button of the matrix. Each bank can be activated for current play by selecting one of its (non-empty) pages. This means that up to 16 pages can be played concurrently. Some restrictions may apply though, due to shortcomings of the MIDI protocol.

* PAGES
One can think of Octopus' pages as track containers. The number of tracks in a page is naturally given to be 10, with a length of 16 steps each. However, musical structures longer than 16 steps can be easily built by chaining tracks in a page, such that they are played consecutively. The chain modes available are: 10 tracks of 1 row (default), 5 tracks of 2 rows, 2 tracks of 4 rows, and 1 track of 8 rows.

If pages are Octopus' track containers, then tracks are the step containers. Apart from other attributes, each track has a locator associated with it which can be controlled independently from locators of other tracks.

In Octopus steps are the smallest meaningful entities, for example notes in a musical context. In track mode the individual steps of a selected track can be modified across their available range of attributes.

All of the above entities of Octopus have attributes associated with them. The range includes but is not limited to: Velocity, Pitch, Length, Start, Position, and others. Generally, attributes can be modified in real time, during play or stop. Their semantics may differ across entities and not all attributes are
applicable to all entities.

Entities or attributes of entities can be operated upon using mutations or functions, for example clear, randomize, modify, copy, paste, and others. While the modify function is mapped directly to the knobs as described in the operation mode section, the others are invoked by pressing the appropriate
mutator buttons.

Octopus features a navigation system that guides the user such as to intuitively trigger valid operations from all possible combinations. Think along the lines of T9 dictionaries in mobile phones.

This section provides an overview of the preliminary Octopus operation modes and documents the base functionality of the user interface by control groups.

Rotary Knobs: n.a.
Track Selectors: Enable the pages of the corresponding row in all banks.
Track Mutators: Mute the pages of the corresponding row in all banks.
Matrix: Select, enable and disable pages from their corresponding banks.
Circle: Save and select grid snapshots, i.e. combinations of pages that lie in more than one matrix row.

* PAGE MODE
Rotary Knobs: The left knobs are hard-wired to attributes, the right knobs are hard-wired to their individual tracks.
Left: each knob has an attribute hardwired with it. Once a track selection has
been made, the corresponding parameters for the selected track(s) can be modified. For example, selecting a track activates the knob group. Turning knob 1 modifies the velocity of the selected track, turning knob 2 modifies its pitch, etc.

Right: the right knob group is dynamically associated with an attribute, by default velocity. In this case, turning knob 1 modifies the velocity of track 1, turning knob 2 modifies the velocity of knob 2, etc.
Track Selectors: Used to identify the tracks the user wishes to modify.
Track Mutators: Per default used to mute and unmute tracks in a page. Double-clicking a track mutator solo'es that particular track. If a track selection has been made, the track mutators are used to call functions upon
the selection.
Matrix: Used to set or unset the steps in tracks.
Circle: The range of functions available in the
initial release is under evaluation.

Rotary Knobs: n.a.
Track Selectors: Select the attribute whose values should be shown in the matrix.
Track Mutators: Call functions upon selected steps Matrix: The attribute values of the individual steps can be visualised and modified in the matrix. Value visualisation takes place using a decimal numeric representation.
Circle: n.a.

This section provides an overview reference of the Octopus functionality. As
described on the previous pages, Octopus’ hardware platform (user interface,
memory, and CPU) is built to allow for a broad range of functions to be
implemented and operated in an intuitive manner.

Technical specifications

Cornerstone features of Octopus include:
- Framework
Sequence pages: 160
Tracks per page: up to 10*
Steps per track: 16, 32, 64 or 128
Track resolution: 16th, 32nd, or 64th of a note
MIDI channels: 32

- User Interface
Principle: chaser light step sequencer
Pushbuttons: 200+ with 3-color LED’s
Rotary knobs: 20+

- Performance
Concurrent play: up to 9 pages or chains thereof
Editing capabilities: full during play, seamless saving
Track play: polyphonic, shuffle, groove, roll

- DIMENSIONS
700 x 450 x 140 mm, 8 Kg