Re: MIDI Program Changes
By Laurent Coray
To John Wale, Jody and all,
> From: Mr J D Wale <essfc@csv.warwick.ac.uk>
>
> Subject: MIDI Program Changes
>
> There has recently been discussion in the MMD of MIDI-operated
> mechanical organs. Thinking through the way MIDI changes sound patches,
> how would one correlate MIDI program change messages to organ stop
> settings ?
I am the owner of Octet Design Corp, and the engineer in charge of the design of our MIDI interface for organs, the UM1. The UM1 is a relay driver as well as a console encoder and stop knobs encoder, which in most cases operates in conjunction with a PC. We are faced with the problem you mentioned and are designing software to take care of the program changes.
The UM1 encodes key presses and stop knob changes as MIDI note messages, one MIDI channel per manual, one or more channels for stops. Usually, a single MIDI wire is sufficient to route this information to the PC. The PC can optionally record this stream with a sequencer software, and edit it and play it back later. The UM1 is also a relay driver, receiving MIDI note messages and driving its outputs accordingly. Usually one MIDI channel per rank, one or more channels for stop relays (if they exist). Large organs require multiple MIDI output ports to reduce delays.
The software we're doing will insert itself before the PC's MIDI outputs; it will receive MIDI messages from the console or the sequencer and route them to the outputs. The note messages that correspond to stops are translated into multiple note messages to drive the appropriate pipes. This translation "table" is programmed by the user with a friendly windows interface. Several tables can be stored on disk for different combinations. A stop can cause any note or range of notes from any manual(s) to drive multiple notes on multiple ranks, with transposition. Mapping is available for percussion instruments. A stop can also cause a program change message and a MIDI program change can be interpreted as a stop. Stop changes can also drive stop relays. Combination changes can drive multiple stop relays (the UM1 has a MIDI sysex message that can change all its outputs simultaneously, eliminating the delay in this case).
We would like to hear any comments, questions or wishes concerning the features of this software so we can make a product that satisfies most demands.
Laurent Coray.
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(Message sent Tue 8 Oct 1996, 16:30:48 GMT, from time zone GMT-0700.) |
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