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Introduction

ZIPI was first described in the Winter 1994 issue of the Computer Music Journal.

What happened to ZIPI?

ZIPI was first described in the Winter 1994 issue of the Computer Music Journal. As with all networking protocols, widespread adoption is critical to their long-term success. Since there were no products announced incorporating ZIPI and none currently in development, it is fair to say that ZIPI is history. I am not qualified to explain why this happened, but it is interesting to examine the ZIPI effort with a view to using its technical contributions in future systems.

Critique

Starting from the bottom up in the OSI layer model, let's look at the physical and data link model proposed in ZIPI. It is clear that IEEE1394 supercedes ZIPI in every respect. It is cheaper since it doesn't require a hub and has simpler interface requirements to modern, high-performance processors. IEEE 1394 is much faster than ZIPI. IEEE1394 includes an isolated, power distribution scheme and hot plugging, unavailable in ZIPI.

A key contribution of ZIPI is the Music Parameter Description Language. Much of the MPDL design involves details of minimal bit encodings for byte-oriented communications over the envisaged physical layer. The huge jump in network bandwidth since ZIPI and the high cost of converting from bit and byte encodings to floating point arithmetic suggest this part of ZIPI is also obsolete.

A contentous part of the MPDL proposal is an explicit addressing hierarchy which is constrained due to bit encoding decisions.

MDPL is the first music network proposal to afford explicit time tagging and latency constraints. MPDL encodes parameters from a rich control space allowing for wind instruments, bowed and plucked strings, and keyboards (MIDI's strength). For the first time, encoding of psychoacoustically-motivated paramaters are included, such as loudness and timbre space. Sound spatialization parameters are also included.

Another important contribution was a scheme to allow ZIPI devices to be queried.

These are lasting contributions that can be readily including in future protocols.

What's Next?

A new team with Adrian Freed and Amar Chaudhary, Sami Khoury, and a couple of the original ZIPI designers, Matt Wright and David Wessel, have developed Open Sound Control Protocol. This protocol, although borrowing nothing from the ZIPI specification itself, addresses many of the issues discovered in the ZIPI effort within the context of networking technology that will be available over the next 10 years.

Adrian Freed, June 1997