The computer running the midiroute program encodes MIDI control data into tagged numbers which are then broadcast to the local network. Each datum is sent through a UDP (User Datagram Protocol) packet to its broadcast destination. Each UDP packet is encapsulated into one ethernet packet under normal conditions and therefore the UDP packets should be received simultaneously by each computer in the local network. This mechanism may be extended into the worldwide network.
In order to communicate with groups of computers in different network locations, we add a relay computer for each group. This relay computer receives IP packets from the midiroute computer and broadcasts UDP packets to its local network.
Latency is the delay time between actual performance gesture input by the performer and the change of sound in the space. Latency must be kept as low as possible in a musical performance system. In our system, the average latency is around 100 msec. The main source of latency is an eight kilobyte sound output buffer in the Windows environment. The impact of other sources of latency, such as network delay or re-synthesis delay, is marginal. Sound output latency should improve with newer generations of sound hardware.
Synchronization error is the difference in latencies within a group of computers receiving the same control data. If the differences are low, errors are noticed as spatial effects (randomized delays between channels) as heard in our system, but if