Details of Midi Protocol
Midi data transmitted via serial bit stream at rate of 31.25 Kbps
Midi messages consist of 8 bit words (1 byte) of binary information
Two types of word: status and data: most significant bit determines whether word is status (1) or data (0)
- Status byte tells sound device type of midi function it will be receiving
- Data byte provides numerical value of the function
- Eg: Note #65 on channel 5 with velocity 90 would be represented by 3 byte command: 10010101 01000001 01011010
“General Midi” standard (GM) provides 16 channels so that 16 different instruments or sounds can simultaneously be played
Two midi modes: omni and poly
In poly mode, each instrument responds only to it’s assigned midi channel; in omni mode, an instrument responds to data on any channel