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# CMIOExtensionStream.ClockType.custom

Indicates that the stream’s clock is specific to the device hosting the stream.

```
case custom
```

## Discussion

The extension doesn’t set this type directly. Instead, the system sets it automatically when you specify a [`CMIOExtensionStreamCustomClockConfiguration`](/documentation/CoreMediaIO/CMIOExtensionStreamCustomClockConfiguration) when you create a [`CMIOExtensionStream`](/documentation/CoreMediaIO/CMIOExtensionStream).

---

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