---
title: sourceTimebase
framework: coremedia
role: symbol
role_heading: Instance Property
path: coremedia/cmtimebase/sourcetimebase
---

# sourceTimebase

Returns the immediate source timebase, if any.

## Declaration

```swift
var sourceTimebase: CMTimebase? { get }
```

## See Also

### Inspecting Timebases

- [time](coremedia/cmtimebase/time.md)
- [rate](coremedia/cmtimebase/rate.md)
- [source](coremedia/cmtimebase/source.md)
- [sourceClock](coremedia/cmtimebase/sourceclock.md)
- [effectiveRate](coremedia/cmtimebase/effectiverate.md)
- [timeAndRate](coremedia/cmtimebase/timeandrate.md)
- [ultimateSourceClock](coremedia/cmtimebase/ultimatesourceclock.md)