---
title: latency
framework: audiotoolbox
role: symbol
role_heading: Instance Property
path: audiotoolbox/auaudiounit/latency
---

# latency

The audio unit’s processing latency, in seconds.

## Declaration

```swift
var latency: TimeInterval { get }
```

## Discussion

Discussion This property reflects the delay between when an impulse arrives in the input stream vs. output stream. This should reflect the delay due to signal processing (e.g. FFTs), not as an effect (e.g. reverberation). Note that a latency that varies with parameter settings, including bypass, is generally not useful to hosts. A host is usually only prepared to add delays before starting to render and those delays need to be fixed. A variable delay would introduce artifacts even if the host could track it. If an algorithm has a variable latency, it should be adjusted upwards to some fixed latency within the audio unit. If for some reason this is not possible, then latency could be regarded as an unavoidable consequence of the algorithm and left unreported (i.e. a value of 0). This version 3 property is bridged to the version 2 kAudioUnitProperty_Latency API.

## See Also

### Optimizing Performance

- [tailTime](audiotoolbox/auaudiounit/tailtime.md)
- [renderQuality](audiotoolbox/auaudiounit/renderquality.md)
- [shouldBypassEffect](audiotoolbox/auaudiounit/shouldbypasseffect.md)
- [canProcessInPlace](audiotoolbox/auaudiounit/canprocessinplace.md)
- [isRenderingOffline](audiotoolbox/auaudiounit/isrenderingoffline.md)