From bruce@ashbysolutions.com Sat Jul 17 07:03:02 2010
Subject:Re: MIDI Running Status [Was: Ventilator + VB3 - V5]

Hi Donn,

MIDI 'running status' was designed to get around the fact that a number
of simultaneous events -- especially note on/off messages -- may happen
at the same time. This is an issue with sequencers, and it's also an
issue with Hammond clones, since certain styles of music (ex: palm
glisses) lead to many notes played all at once. MIDI is moderately
fast, but it's limited to about 1,000 messages per second.

A MIDI Note On (or Note Off) message is composed of three bytes --

1 - Note On + Channel
2 - Key Number
3 - Velocity

If a bunch of Note On messages come from the same channel in a row, MIDI
allows the first byte to be dropped:

1 - Note On + CH3
2 - Key #13
3 - Vel=100
4 - Key #14
5 - Vel=110
6 - Key #16
7 - Vel=107
etc.

So, on long strings, there is about a 33% time savings. This situation
gets more complicated because MIDI also allows a Note On with Vel=0 to
be substituted for a Note Off. Many keyboards use this method, so once
the first note is sent, it may be a while before another Command byte is
sent.

Regards,

-BW

Bruce Wahler
Ashby Solutions.com^(TM)
bruce@ashbysolutions.com
http://music.ashbysolutions.com

On 7/17/2010 9:26 AM, Donald Watson wrote:
> Dave,