---
title: streamActiveFormatIndex
framework: coremediaio
role: symbol
role_heading: Type Property
path: coremediaio/cmioextensionproperty/streamactiveformatindex
---

# streamActiveFormatIndex

A property key for the index of the active stream format.

## Declaration

```swift
static let streamActiveFormatIndex: CMIOExtensionProperty
```

## Discussion

Discussion The property state for this property is a number.

## See Also

### Stream Properties

- [streamFrameDuration](coremediaio/cmioextensionproperty/streamframeduration.md)
- [streamMaxFrameDuration](coremediaio/cmioextensionproperty/streammaxframeduration.md)
- [streamSinkBufferQueueSize](coremediaio/cmioextensionproperty/streamsinkbufferqueuesize.md)
- [streamSinkBuffersRequiredForStartup](coremediaio/cmioextensionproperty/streamsinkbuffersrequiredforstartup.md)
- [streamSinkBufferUnderrunCount](coremediaio/cmioextensionproperty/streamsinkbufferunderruncount.md)
- [streamSinkEndOfData](coremediaio/cmioextensionproperty/streamsinkendofdata.md)