towards real-time interactive performance environments - multiple players

8/8/2019 Towards Real-Time Interactive Performance Environments - Multiple Players

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Towards Real-time Interactive Performance

Environments

Project I: Multiple Players


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Interactivity

Interaction is a two-way street. - Winkler (1998)

Interaction means mutual influence. - Pressing (1990)


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Project Aims:

Develop real-time performance analysis strategies throughsegmentation of an incoming

audio signal;

Develop musically relatedyet unpredictable algorithmic responses derived from real-time performance analysis;

Explore notions of performer and systemcontroland influence over algorithmic

responses and interactive mappings;

Provide a balance betweenfixedand user modifiable interactive mappings.


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Defining Interactive Music Systems:

Interactive computer music systems are those whose behaviour changes in response tomusical input. Such responsiveness allows these systems to participate in live

performance of both notated and improvised music. - Rowe (1993)

Interactive music is () a music composition or improvisation where software interprets alive performance to affect music generated or modified by computers. Usually this

involves a performer playing an instrument while a computer creates music that is insome way shaped by the performance. - Winkler (1998)

An interactive system has the potential for variation and unpredictability in its response,

and depending on the context may well be considered more in terms of a composition orstructured improvisation than an instrument. - Drummond (2009)


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Interactive Models and Classifications:

Rowe and Winkler

Robert Rowes system classifications:

score-driven vs. performance-driven systems transformative, generative or sequenced response types

instrument paradigm vs. player paradigm

Todd Winklers interactive models:

conducted classical orchestra string quartet

jazz combo

free improvisation ensemble


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System Anatomies:

Rowe and Winkler

Rowes System Anatomy:

Sensing Processing Response

Winklers System Anatomy:

Human Input Listening Interpretation Composition Sound


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Multiple Players

interactive performance environment for

live instrumentalist and three virtual players

System classification:

aperformance-driven interactive system;

makes use ofgenerative algorithms in responding to performer input;

conceptually linked to Rowesplayer-paradigm classification.

System anatomy:

Passive Sensing Active Sensing Composition/

(Hearing) (Listening) Improvisation

Human Input Sound

OutputSystem Input

Control and Influence

Influence


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Performance analysis strategies:

Segmentation and MIDI Representation

Pitch analysis - when above user specified amplitude threshold, pitch of incoming audiosignal extracted and represented asMIDI note numberusing FFT analysis techniques -MSP

fiddle~ object;

Discrete amplitude analysis - amplitude of individual pitches above threshold converted toMIDI velocity values and packed with corresponding pitches -MSP fiddle~ objectandamplitude-velocity scaling;

Rhythm - time interval (ms) between successive pitch onsets calculated -Delta-time/Inter-Onset-Interval(IOI) calculation;

Articulation - time interval (ms) between pitch onset and pitch end calculated (positivethreshold crossing = pitch onset/MIDI note-on,negative threshold crossing = pitch end/MIDInote-off).

Legato movementcalculated as equalingDelta-time/IOI(no negative threshold detectedbefore new pitch onset -MIDI note-offtriggered before newMIDI note-on).


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System Response:

Option 1) Probability - Normal Distribution

Normal distribution treats each event as a discrete event, making outputoblivious to what came before

Number of occurrences of chromatic pitches in this example:

Probability weightings: C4 - 3, E - 2, C3 - 1, G - 1

C3 = 1 C#3 = 0 D3 = 0 D#3 = 0 E3 = 2 F3 = 0

F#3 = 0

C4 = 3

G3 = 1 G# = 0 A3 = 0 A#3 = 0 B3 = 0


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System Response:

Option 2) Probability - 1st Order Markov Chain

Markov chains take transitions from one state to another into consideration

Transition weightings for current example (after one repetition):

C3 - C3 = 0 E3 - C3 = 0 G3 - C3 = 0 C4 - C3 = 1

C3 - E3 = 1 E3 - E3 = 1 G3 - E3 = 0 C4 - E3 = 0

C3 - G3 = 0 E3 - G3 = 1 G3 - G3 = 0 C4 - G3 = 0

C3 - C4 = 0 E3 - C4 = 0 G3 - C4 = 1 C4 - C4 = 2


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Levels and Directions of Control:

Start/Stop Performance:

live performer all players; (held note trigger) - predictable, user-defined

live performer one player; (note count after rest) - semi-predictable, user-defined

one player one player; (note count) - semi-predictable, user-defined

Memory Loss:

live performer one player; (note count after rest) - semi-predictable, user-defined

one player one player; (note count) - semi predictable, user-defined

Synchronised Playback:

live performer players 1 & 2; (held note trigger) - predictable, user-defined live performer one player; (time threshold) - predictable, fixed

one player one player; (time threshold) - predictable, fixed


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Directions of Influence:

Influence is defined as the possibility that the output of either the live performer or any

virtual player will directly or indirectly affect the potential future output of another

live performer output one player output; semi-predictable, user defined

one player output one player output;semi-predictable, user defined

any/all players outputs live performer output; unpredictable

towards real-time interactive performance environments - multiple players

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