MIDI CC64: what the sustain pedal actually is
In a MIDI file the sustain pedal is not a note and not a note length. It is a separate stream of messages called CC64, and whether a file has it decides how editable that file really is.
What CC64 means
MIDI carries two different kinds of information. Notes say which key, when, how hard. Control changes say everything else about the performance, and each one has a number. Number 64 is the sustain pedal, sometimes written CC64 or, in older documentation, the damper pedal — the same pedal this site is named after.
Each CC64 message carries a value from 0 to 127. The standard reading is a switch:
| 0 to 63 | Pedal up. The dampers rest on the strings and the sound stops when the key is released. |
|---|---|
| 64 to 127 | Pedal down. The dampers lift, so notes keep ringing after the fingers leave the keys. |
Some pianos and sampled instruments go further and read the whole range as a position rather than a switch, which is how half-pedalling is expressed. Whether that happens depends entirely on the instrument reading the file, not on the file itself. A file that only ever writes 0 and 127 works everywhere; a file that writes intermediate values works well on instruments that understand them and is rounded to a switch on those that do not.
Why it matters more than it sounds
Take a slow chord progression where the pianist holds the pedal through each bar. There are two ways to record what you hear.
The honest way is to write the notes with the length the fingers actually held, then write a CC64 down at the start of the bar and a CC64 up at the end. The file now contains the same two layers the pianist played: hands and foot.
The shortcut is to write no pedal at all and simply make every note long enough to cover the ringing. It sounds roughly similar on playback. It falls apart the moment you do anything else with it:
- The notation is wrong. Import it into a score editor and you get a forest of tied whole notes instead of the crotchets that were actually played.
- Editing fights you. Change one chord and the overlaps have to be redrawn by hand, because the length is carrying information that was never about length.
- The pedal is unrecoverable. You cannot separate "held by the finger" from "held by the foot" after the fact, because the file no longer distinguishes them.
- Re-performing is impossible. Feed it to a sampled piano with real pedal resonance and you get nothing, because there is no pedal to respond to.
How to check a MIDI file for CC64
You do not have to take anyone's word for it, including ours.
- In a DAW. Open the file, then open the automation or controller lane under the piano roll and look for a lane named Sustain, Damper, or CC64. An empty lane means the file has no pedal in it.
- By eye, in the piano roll. If nearly every note runs into the next one with no gaps anywhere, and there is no pedal lane, the lengths are doing the pedal's job.
- By reading the file. Any MIDI library will list the control changes. What you want to see is a run of CC64 messages spread through the piece, not two at the start.
What a good pedal track looks like
A useful CC64 track has roughly as many pedal changes as the music has harmonic changes, and the changes land where a pianist's foot would move: at a chord change, usually at the exact moment a new note is struck, not halfway between notes.
Two failure modes are easy to spot. Too few events — a pedal pressed once at bar one and released at the end — means the tool guessed rather than listened. Too many events, several per beat, usually means the tool reacted to every low note in an arpeggio and treated each one as a new harmony.
How Damper writes it
Damper reconstructs the pedal from the harmony it hears in the recording, then places each change on a real note onset rather than at an arbitrary point in time. That second step is what stops an arpeggiated left hand from producing four pedal changes per bar.
On the reference set used for calibration — ten pieces pedalled by hand, 433 pedal events — roughly three changes out of four land within a sixteenth of a beat of the hand-marked position. That is a measurement on one specific set, not a promise about your recording: heavy reverb, or a piano very unlike the calibration material, will do worse.
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