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# VTCopyVideoDecoderExtensionProperties

Returns information about the Media Extension video decoder required to decode the specified format.

```
extern OSStatus VTCopyVideoDecoderExtensionProperties(CMFormatDescriptionRef formatDesc, CFDictionaryRef*mediaExtensionPropertiesOut);
```

## Parameters

`formatDesc`

The format description for the video format for which information is being requested.

`mediaExtensionPropertiesOut`

If a <doc://com.apple.documentation/documentation/MediaExtension> video decoder will be used to decode the specified format, this pointer will return a dictionary with a set of properties describing the extension video decoder. The dictionary keys are VTExtensionPropertiesKey values.

## Return Value

If the function succeeds and a <doc://com.apple.documentation/documentation/MediaExtension> video decoder will be used to decode this format, the return value will be `noErr`. If the function succeeds but a Media Extension video decoder will not be used to decode this format, the return value will be [`kVTCouldNotFindExtensionErr`](/documentation/VideoToolbox/kVTCouldNotFindExtensionErr). Otherwise, the return value will be an error code describing the failure.

## Discussion

If a Media Extension video decoder will be used to decode the specified format, this function will return information about the Media Extension that will be used.

---

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