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How MIDI Works Over USB

Same MIDI Messages, Different Connection

When you use MIDI over USB, the MIDI messages themselves (like Note On, Note Off, Control Change) don’t change. What changes is how those messages travel from one device to another.

Instead of using a MIDI DIN cable (the round one with 5 pins), you use a USB cable, like the one you’d use for a printer or external hard drive.

MIDI over USB is a faster, more flexible way to send MIDI messages. The messages are the same, but USB lets them travel more efficiently and allows extra features like multiple MIDI ports, power supply, and easy connection to computers.

Some instruments and controllers have both DIN and USB MIDI. You can use whichever works best for your setup.

How USB Sends MIDI Messages

USB works differently than DIN MIDI. It sends data in packets — small groups of bytes sent very fast.

Each MIDI message (for example, a 3-byte Note On message) is packed into a USB MIDI Event Packet. This packet always has 4 bytes:

  1. Info about the message type and virtual cable number
  2. The original MIDI status byte (e.g., Note On)
  3. First data byte (e.g., note number)
  4. Second data byte (e.g., velocity)

Example: Playing middle C

MIDI message: 0x90 0x3C 0x64
USB packet: 0x09 0x90 0x3C 0x64
The first byte tells the computer, “This is a Note On message on virtual cable 0.”

Why USB MIDI is Better in Many Cases

  • Faster: USB sends data much faster than DIN MIDI. No delays, even with lots of data.
  • Two-way communication: One USB cable can send and receive MIDI at the same time. DIN needs two cables for that.
  • Multiple MIDI ports: One USB cable can carry several MIDI connections at once (useful for large setups).
  • Plug-and-play: Most USB MIDI devices work without installing drivers.
  • Power via USB: Many devices get their power from USB — no extra power cable needed.

USB-MIDI Class – Standard Protocol

MIDI over USB follows the USB-MIDI Class Specification (developed by the USB Implementers Forum and the MIDI Manufacturers Association). Devices that follow this spec are plug-and-play — no special drivers needed on modern systems (e.g., Windows, macOS, Linux, iOS).