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# initialSegmentStartTime

The start time of the initial segment.

```
var initialSegmentStartTime: CMTime { get set }
```

## Discussion

This value is relevant only when the [`preferredOutputSegmentInterval`](/documentation/AVFoundation/AVAssetWriter/preferredOutputSegmentInterval) property value is positive numeric, in which case you must set a numeric time.

You can’t change this value after writing starts.

---

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