---
title: extensions
framework: corevideo
role: symbol
role_heading: Instance Property
path: corevideo/cvproresrawmetadata/extensions
---

# extensions

ProRes RAW metadata extensions. This Data contains a big-endian UInt32 representing the size of the item in bytes followed by a 4-character code (‘psim’) followed by a variable-length pascal string identifying the metadata (like a key string) followed by the metadata payload.

## Declaration

```swift
var extensions: Data?
```