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# kVTCompressionPropertyKey_FieldDetail

Field ordering for encoded interlaced frames.

```
let kVTCompressionPropertyKey_FieldDetail: CFString
```

## Discussion

If a video encoder enforces specific field ordering, this property will be read-only ([`VTSessionSetProperty(_:key:value:)`](/documentation/VideoToolbox/VTSessionSetProperty(_:key:value:)) returns [`kVTPropertyReadOnlyErr`](/documentation/VideoToolbox/kVTPropertyReadOnlyErr)). The field detail is set on the format description for output samples, and may affect source frame scaling. `NULL` is a valid value for this property.

---

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