---
title: "CMTimebaseCopyUltimateSourceClock(_:)"
framework: coremedia
role: symbol
role_heading: Function
path: "coremedia/cmtimebasecopyultimatesourceclock(_:)"
---

# CMTimebaseCopyUltimateSourceClock(_:)

Returns the source clock that’s the source of all of a timebase’s source timebases.

## Declaration

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

## See Also

### Copying Timebases

- [CMTimebaseCopySource(_:)](coremedia/cmtimebasecopysource(_:).md)
- [CMTimebaseCopySourceClock(_:)](coremedia/cmtimebasecopysourceclock(_:).md)
- [CMTimebaseCopySourceTimebase(_:)](coremedia/cmtimebasecopysourcetimebase(_:).md)