---
title: "CMTimebaseCopySourceClock(_:)"
framework: coremedia
role: symbol
role_heading: Function
path: "coremedia/cmtimebasecopysourceclock(_:)"
---

# CMTimebaseCopySourceClock(_:)

Returns the immediate source clock of a timebase.

## Declaration

```swift
func CMTimebaseCopySourceClock(_ timebase: CMTimebase) -> CMClock?
```

## See Also

### Copying Timebases

- [CMTimebaseCopySource(_:)](coremedia/cmtimebasecopysource(_:).md)
- [CMTimebaseCopySourceTimebase(_:)](coremedia/cmtimebasecopysourcetimebase(_:).md)
- [CMTimebaseCopyUltimateSourceClock(_:)](coremedia/cmtimebasecopyultimatesourceclock(_:).md)