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# AVCompositionTrackSegment

A track segment that maps a time from the source media track to the composition track.

```
class AVCompositionTrackSegment
```

## Overview

You typically use this class to save a low-level representation of a composition.

## Topics

### Creating a segment

[`compositionTrackSegmentWithTimeRange:`](/documentation/AVFoundation/AVCompositionTrackSegment/compositionTrackSegmentWithTimeRange:)

Returns a new object that presents an empty composition track segment.

[`init(timeRange:)`](/documentation/AVFoundation/AVCompositionTrackSegment/init(timeRange:))

Creates an object that presents an empty composition track segment.

[`compositionTrackSegmentWithURL:trackID:sourceTimeRange:targetTimeRange:`](/documentation/AVFoundation/AVCompositionTrackSegment/compositionTrackSegmentWithURL:trackID:sourceTimeRange:targetTimeRange:)

Returns a new an object that presents a segment of a media file that the specified URL references.

[`init(url:trackID:sourceTimeRange:targetTimeRange:)`](/documentation/AVFoundation/AVCompositionTrackSegment/init(url:trackID:sourceTimeRange:targetTimeRange:)-4rc2g)

Creates an object that presents a segment of a media file that the specified URL references.

### Accessing segment properties

[`sourceURL`](/documentation/AVFoundation/AVCompositionTrackSegment/sourceURL)

A URL of the container file whose media this track segment presents.

[`sourceTrackID`](/documentation/AVFoundation/AVCompositionTrackSegment/sourceTrackID)

An identifier of a track in the container file whose media this track segment presents.

[`isEmpty`](/documentation/AVFoundation/AVCompositionTrackSegment/isEmpty)

A Boolean value that indicates whether the segment is empty.


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