ZIPI
Encyclopedia
Zeta Instrument Processor Interface (ZIPI) was a research project initiated by Zeta Instruments and UC Berkeley's CNMAT
(Center for New Music and Audio Technologies). Introduced in 1994 in a series of publications in Computer Music Journal
from MIT Press
, ZIPI was intended as the next-generation transport protocol for digital musical instruments, designed with compliance to OSI model
.
connection, ZIPI was designed to run over a star network
with a hub in the center. This allowed for faster connection and disconnection, because there was no need to daisy-chain multiple devices. Ethernet
10Base-T
was used at the physical layer
, but the authors tried to distance themselves from physical implementation as much as possible.
There were proposals for query
ing device capabilities, patch
names and other system and patch parameters, as well as uploading and downloading samples
into device memory.
. MPDL used a three-level hierarchy of up to 63 Families consisting of 127 Instruments, each having 127 notes, resulting in up to 1,016,127 individual note addresses. Instruments in a Family could be assembled from different physical devices.
This arrangement allowed fine per-note control of synthesis parameters, which was especially useful for non-standard scenarios such as MIDI wind controller or MIDI guitar controller. For example, instant note-on capability could mask the deficiencies of note detection (tracking) in guitar MIDI systems, especially on lower strings. When triggered, the note would begin sounding as a noise or an arbitrary low note until the controller logic had tracked
the actual pitch, which would be sent by a follow-up message without the need to retrigger the note. Conventionally, messages could also address a whole Instrument or an entire Family.
Some MDPL messages were direct carryovers from MIDI, given more pronounceable names in order to avoid ambiguity
, but most messages were new and were based on a very different, although innovative control logic. The resolution of message parameters could be any multiple of 8-bit
, potentially extending 7-bit resolution typical of MIDI to 32 or more bits.
There were also some higher-level messages corresponding to advanced program parameters, such as modulation
, envelopes and 3D spatialization
of voices.
Controller (performance-oriented) messages included:
.
As no commercial devices were released supporting ZIPI, the introduction of the superior "FireWire" (IEEE1394) standard and the sufficiency of MIDI for most applications soon led to the practical demise of the project. The web site that is home to the ZIPI project asserts that IEEE1394 "supersedes ZIPI in every respect," mainly because it does not require a hub and has simpler interface requirements for modern devices. IEEE 1394 is much faster than ZIPI, to be sure. IEEE1394 also includes an isolated power distribution scheme and hot plugging (devices may be added or removed more conveniently), both of which were not supported in ZIPI.
The developers continued on to work on Open Sound Control protocol, currently supported in a wide variety of musical instruments, sensors and software.
CNMAT
CNMAT , The Center for New Music and Audio Technologies, is a multidisciplinary research center within University of California, Berkeley Department of Music. The Center's goal is to provide a common ground where music, cognitive science, computer science, and other disciplines meet to...
(Center for New Music and Audio Technologies). Introduced in 1994 in a series of publications in Computer Music Journal
Computer Music Journal
Computer Music Journal is an American academic journal that covers a wide range of topics related to digital audio signal processing and electroacoustic music. It is published on-line and in hard copy by MIT Press. The magazine is accompanied by an annual CD/DVD that collects audio and video work...
from MIT Press
MIT Press
The MIT Press is a university press affiliated with the Massachusetts Institute of Technology in Cambridge, Massachusetts .-History:...
, ZIPI was intended as the next-generation transport protocol for digital musical instruments, designed with compliance to OSI model
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
.
Concept
The draft working version of ZIPI was primarily aimed at addressing many limitations of MIDI (Musical Instrument Digital Interface). Unlike MIDI which uses a peer-to-peer serial portSerial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
connection, ZIPI was designed to run over a star network
Star network
Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages...
with a hub in the center. This allowed for faster connection and disconnection, because there was no need to daisy-chain multiple devices. Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
10Base-T
10BASE-T
Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. Other Ethernet cable standards employ coaxial cable or optical fiber. Early versions developed in the 1980s included StarLAN followed by 10BASE-T. By the 1990s, fast, inexpensive...
was used at the physical layer
Physical layer
The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....
, but the authors tried to distance themselves from physical implementation as much as possible.
There were proposals for query
Information retrieval
Information retrieval is the area of study concerned with searching for documents, for information within documents, and for metadata about documents, as well as that of searching structured storage, relational databases, and the World Wide Web...
ing device capabilities, patch
Patch (computing)
A patch is a piece of software designed to fix problems with, or update a computer program or its supporting data. This includes fixing security vulnerabilities and other bugs, and improving the usability or performance...
names and other system and patch parameters, as well as uploading and downloading samples
Sampling (music)
In music, sampling is the act of taking a portion, or sample, of one sound recording and reusing it as an instrument or a different sound recording of a song or piece. Sampling was originally developed by experimental musicians working with musique concrète and electroacoustic music, who physically...
into device memory.
MPDL
ZIPI used completely new event system and complex note addressing schemes. At the heart of the new protocol was Music Parameter Description Language seen as a direct replacement to MIDI eventsEvent-driven programming
In computer programming, event-driven programming or event-based programming is a programming paradigm in which the flow of the program is determined by events—i.e., sensor outputs or user actions or messages from other programs or threads.Event-driven programming can also be defined as an...
. MPDL used a three-level hierarchy of up to 63 Families consisting of 127 Instruments, each having 127 notes, resulting in up to 1,016,127 individual note addresses. Instruments in a Family could be assembled from different physical devices.
This arrangement allowed fine per-note control of synthesis parameters, which was especially useful for non-standard scenarios such as MIDI wind controller or MIDI guitar controller. For example, instant note-on capability could mask the deficiencies of note detection (tracking) in guitar MIDI systems, especially on lower strings. When triggered, the note would begin sounding as a noise or an arbitrary low note until the controller logic had tracked
Tracking
Tracking can refer to:*Tracking , separating children into different classes according to their academic ability*Tracking, in computer graphics, a vital part of match moving...
the actual pitch, which would be sent by a follow-up message without the need to retrigger the note. Conventionally, messages could also address a whole Instrument or an entire Family.
Some MDPL messages were direct carryovers from MIDI, given more pronounceable names in order to avoid ambiguity
Ambiguity
Ambiguity of words or phrases is the ability to express more than one interpretation. It is distinct from vagueness, which is a statement about the lack of precision contained or available in the information.Context may play a role in resolving ambiguity...
, but most messages were new and were based on a very different, although innovative control logic. The resolution of message parameters could be any multiple of 8-bit
8-bit
The first widely adopted 8-bit microprocessor was the Intel 8080, being used in many hobbyist computers of the late 1970s and early 1980s, often running the CP/M operating system. The Zilog Z80 and the Motorola 6800 were also used in similar computers...
, potentially extending 7-bit resolution typical of MIDI to 32 or more bits.
There were also some higher-level messages corresponding to advanced program parameters, such as modulation
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
, envelopes and 3D spatialization
Surround sound
Surround sound encompasses a range of techniques such as for enriching the sound reproduction quality of an audio source with audio channels reproduced via additional, discrete speakers. Surround sound is characterized by a listener location or sweet spot where the audio effects work best, and...
of voices.
Message types
The basic synthesis control messages were:- Articulation - 'note on/off' in MIDI
- Pitch (note number and offset in 0.2 cents)
- Frequency (in Hz)
- Loudness - 'velocity' in MIDI
- Amplitude - 'volume' in MIDI
- Even/Odd Harmonic balance
- Pitched/Unpitched balance
- Roughness
- Attack character
- Inharmonicity
- Pan Left/Right, Up/Down, Front/Back
- Spatialization distance and azimuth/elevation angles
- Program Change - immediately and future notes
- Timbre space X/Y/Z
- Multiple output levels
- Time tag
- Modulation rate/depth/wavetype
Controller (performance-oriented) messages included:
- Key Velocity/Number/Pressure
- Pitch Bend Wheel
- Mod Wheel 1/2/3
- Switch pedal 1 (Sustain)/ 2 (Soft pedal) /3 /4
- Continuous pedal 1 (Volume)/2 /3 /4
- Pick/Bow Velocity/Position/Pressure
- Fret/fingerboard position/pressure
- Wind flow or pressure (breath controller)
- Embouchure (bite)
- Wind controller keypads
- Lip pressure/frequency
- Drum head striking point X/Y position and distance/angle from center
- X/Y/X position in space
- Velocity in X/Y/Z dimension
- Acceleration in X/Y/Z dimension
Outcome of the project
Although ZIPI provided many outstanding new features, they did not line up well with existing MIDI-based implementations. The unusual addressing scheme which required substantial increase in complexity was the main factor in the lack of its adoption. Maintaining 1,016,127 individual synthesis states was far beyond the capabilities of synth hardware of the time, even though ZIPI developers hinted that there would be some practical limits upon the number of simultaneously available programs and notes. In comparison, MIDI defined only 16 channels that accumulated common channel control messages like program change, volume and pitch, and most digital systhesizers of the time could only provide from 12 to 128 simultaneously sounding notesPolyphony (instrument)
Polyphony Instruments that are not capable of polyphony are monophonic.-Synthesizer:Most of early synthesizers were monophonic musical instruments which can play only one note at a time, and are often called monosynth as opposed to polysynth...
.
As no commercial devices were released supporting ZIPI, the introduction of the superior "FireWire" (IEEE1394) standard and the sufficiency of MIDI for most applications soon led to the practical demise of the project. The web site that is home to the ZIPI project asserts that IEEE1394 "supersedes ZIPI in every respect," mainly because it does not require a hub and has simpler interface requirements for modern devices. IEEE 1394 is much faster than ZIPI, to be sure. IEEE1394 also includes an isolated power distribution scheme and hot plugging (devices may be added or removed more conveniently), both of which were not supported in ZIPI.
The developers continued on to work on Open Sound Control protocol, currently supported in a wide variety of musical instruments, sensors and software.