---
title: "init(formatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:)"
framework: coremediaio
role: symbol
role_heading: Initializer
path: "coremediaio/cmioextensionstreamformat/init(formatdescription:maxframeduration:minframeduration:validframedurations:)"
---

# init(formatDescription:maxFrameDuration:minFrameDuration:validFrameDurations:)

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

## Declaration

```swift
@nonobjc convenience init(formatDescription: CMFormatDescription, maxFrameDuration: CMTime, minFrameDuration: CMTime, validFrameDurations: [CMTime]?)
```

## Parameters

- `formatDescription`: The format of the samples that a stream delivers.
- `maxFrameDuration`: The maximum frame duration the stream supports.
- `minFrameDuration`: The minimum frame duration the stream supports.
- `validFrameDurations`: A discrete set of supported frame durations.