---
title: mediaSubType
framework: avfoundation
role: symbol
role_heading: Type Property
path: avfoundation/avcaptionsettingskey/mediasubtype
---

# mediaSubType

A key that identifies the output media subtype of a caption conversion operation.

## Declaration

```swift
static let mediaSubType: AVCaptionSettingsKey
```

## Discussion

Discussion This key supports numeric and string forms of media subtypes for caption conversions.

## See Also

### Keys

- [mediaType](avfoundation/avcaptionsettingskey/mediatype.md)
- [timeCodeFrameDuration](avfoundation/avcaptionsettingskey/timecodeframeduration.md)
- [useDropFrameTimeCode](avfoundation/avcaptionsettingskey/usedropframetimecode.md)