---
title: kAudioUnitProperty_MatrixLevels
framework: audiotoolbox
role: symbol
role_heading: Global Variable
path: audiotoolbox/kaudiounitproperty_matrixlevels
---

# kAudioUnitProperty_MatrixLevels

Describes the internal state of a matrix mixer.

## Declaration

```swift
var kAudioUnitProperty_MatrixLevels: AudioUnitPropertyID { get }
```

## Discussion

Discussion Calculate the size required for this property’s value as follows: (input channel count + 1) * (output channel count + 1) Obtain the channel counts using the kAudioUnitProperty_MatrixDimensions property. For example, consider a matrix mixer that has 2 input channels and 2 output channels. The value of this property then requires a 3 x 3 array of Float32 values. You can retrieve specific pieces of information for this example matrix mixer’s state as follows: Global volume is stored at volumes[2][2] Input volumes are stored in the last column: first input channel at volumes[0][2]; second input channel at volumes[1][2] Output volumes are stored in the last row: first output channel at volumes [2][0]; second output channel at volumes[2][1] Cross-point volumes are stored at their expected locations(volumes[0][1], etc) A read-only two-dimensional array of Float32 values valid on the audio unit global scope.

## See Also

### Constants

- [kAudioUnitProperty_InputAnchorTimeStamp](audiotoolbox/kaudiounitproperty_inputanchortimestamp.md)
- [kAudioUnitProperty_MatrixDimensions](audiotoolbox/kaudiounitproperty_matrixdimensions.md)
- [kAudioUnitProperty_MeterClipping](audiotoolbox/kaudiounitproperty_meterclipping.md)
- [kAudioUnitProperty_MeteringMode](audiotoolbox/kaudiounitproperty_meteringmode.md)