What is MIDI and how does it work?

MIDI stores performance instructions rather than a recording of sound.

What a MIDI file contains

A MIDI file can contain note pitches, start times, durations, velocities, channels, tempo changes and controller messages. A synthesizer or instrument plugin turns those instructions into sound.

Why the same file can sound different

The receiving instrument, patch, routing, tuning and automation affect playback. A file can contain valid notes and still sound silent when the receiving track is muted or listening on another channel.

Inspect before changing

1. Open a copy in the MIDI inspector.
2. Check note counts, channels, Program Change and controller messages.
3. Make one deliberate change and compare the exported copy with the original.