A2 MIDI Questions

August 30, 2018 Off By Huy

1. Explain the historical background of the MIDI protocol. When was it established, and what type of “performance gesture” was it first designed to capture?

MIDI is a protocol that allowed the synthesizers to communicate with each other. Established in 1984, MIDI is designed to capture: the note, the velocity, the channel, whether foot pedal is down or not, whether any slides or joysticks are moved, and change the sounds stored in the memory.

2. Explain MIDI as an 8 bit system. How do Status Byte and Data Bytes differ as regards the MSB (most significant bit). What is the lowest possible status byte (expressed as base 10 number?) What is the highest possible data byte (expressed as a base 10 number)?

8 bit system means that it is a series of potential numerical values, from 0 to 255. Data bytes are identified as numbers with a 0 in the left-most column, Status bytes have a 1 in the leftmost column. Lowest status byte should be 1000000, which is 128. Highest data byte should be 127.

3. Explain the configuration of a Note On message. What does the status byte represent, and how many data bytes are necessary for a complete Note On message?

A note on message has:

A status byte between 144 and 159, meaning note on, channel 1-16

A data byte between 0-127, which note

A data byte between 0-127, velocity

2 data bytes are needed.


4. Similarly, explain the configuration of a Controller message (messages from sliders, joysticks, buttons, food pedals, wind controllers, etc.) What does the status byte represent, and how many data bytes are necessary for a complete Controller message?

Status Byte 176-191, message on 16 channels

Data byte 0-127, controller number

Data byte 0-127, controller value

Status byte represents controller data.

5. Why is the status byte of a patch change message followed by only one data byte?

It only changes the patch on the synthesizer.

6. How are MIDI notes turned off? Is there a separate note off message, or is this managed in a different (and somewhat musically unintuitive!) way?

Just a note on, velocity 0.

7. Explain how MIDI channels work in relationship to Note on and Controller messages.

Basically it can send messages over 16 different channels at almost the same time.

8. How is a midi file structured in relationship to a millisecond time stamp?

It transmits along a wire at about 32,000 bits per second. One massage travels at about 1 per millisecond

9. Imagine a drum pad trigger, where each pad triggers a different MIDI note. How would you set up a little computer program that would play different instruments on a drum kit? What would the velocities represent?

I don’t know… Maybe use the velocity to signify different instruments?