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# CMIOExtensionStreamFormat

An object that describes the format of a media stream.

```
class CMIOExtensionStreamFormat
```

## Topics

### Creating a Stream Format

[`init(formatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:)`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/init(formatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:))

Creates a stream format with a format description and frame durations.

[`streamFormatWithFormatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/streamFormatWithFormatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:)

Returns a new stream format with a format description and frame durations.

[`initWithFormatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/initWithFormatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:)

Creates a stream format with a format description and frame durations.

### Configuring Frame Durations

[`minFrameDuration`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/minFrameDuration)

The minimum frame duration a stream supports.

[`maxFrameDuration`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/maxFrameDuration)

The maximum duration a stream supports.

[`validFrameDurations`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/validFrameDurations-707st)

An array of frame durations the stream supports.

[`validFrameDurations`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/validFrameDurations-4rbay)

An array of frame durations the stream supports.

### Accessing the Format Description

[`formatDescription`](/documentation/CoreMediaIO/CMIOExtensionStreamFormat/formatDescription)

A description of the format of the stream’s media samples.


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