---
title: HostCallback_GetMusicalTimeLocation
framework: audiotoolbox
role: symbol
role_heading: Type Alias
path: audiotoolbox/hostcallback_getmusicaltimelocation
---

# HostCallback_GetMusicalTimeLocation

When called by the system, provides musical timing information to an audio unit from a host application.

## Declaration

```swift
typealias HostCallback_GetMusicalTimeLocation = (UnsafeMutableRawPointer?, UnsafeMutablePointer<UInt32>?, UnsafeMutablePointer<Float32>?, UnsafeMutablePointer<UInt32>?, UnsafeMutablePointer<Float64>?) -> OSStatus
```

## Parameters

- `inHostUserData`: Custom data that you provided when registering your callback with the audio unit.
- `outDeltaSampleOffsetToNextBeat`: On output, the number of samples until the next beat.
- `outTimeSig_Numerator`: On output, the numerator for a musical time signature.
- `outTimeSig_Denominator`: On output, the denominator for a musical time signature.
- `outCurrentMeasureDownBeat`:

## Discussion

Discussion If you named your callback function MyHostCallback_GetMusicalTimeLocation, you would declare it like this:

## See Also

### Getting Information from the Host

- [HostCallback_GetBeatAndTempo](audiotoolbox/hostcallback_getbeatandtempo.md)
- [HostCallback_GetTransportState](audiotoolbox/hostcallback_gettransportstate.md)
- [HostCallback_GetTransportState2](audiotoolbox/hostcallback_gettransportstate2.md)
- [AUInputSamplesInOutputCallback](audiotoolbox/auinputsamplesinoutputcallback.md)
- [AUMIDIOutputCallback](audiotoolbox/aumidioutputcallback.md)