---
title: velocity
framework: avfaudio
role: symbol
role_heading: Instance Property
path: avfaudio/avextendednoteonevent/velocity
---

# velocity

The MDI velocity.

## Declaration

```swift
var velocity: Float { get set }
```

## Discussion

Discussion If the instrument in the AVMusicTrack destination audio unit supports fractional values, use this to generate precise changes in gain and other values. The valid range of values depend on the destination audio unit, and is usually between 0.0 and 127.0.

## See Also

### Configuring a Note On Event

- [midiNote](avfaudio/avextendednoteonevent/midinote.md)
- [instrumentID](avfaudio/avextendednoteonevent/instrumentid.md)
- [groupID](avfaudio/avextendednoteonevent/groupid.md)
- [duration](avfaudio/avextendednoteonevent/duration.md)