---
title: kVTCompressionPropertyKey_ConstantQualityFactor
framework: Video Toolbox
role: symbol
role_heading: Global Variable
platforms: [iOS 27.0+, iPadOS 27.0+, Mac Catalyst 27.0+, macOS 27.0+, tvOS 27.0+, visionOS 27.0+]
path: videotoolbox/kvtcompressionpropertykey_constantqualityfactor
---

# kVTCompressionPropertyKey_ConstantQualityFactor

## Declaration

```swift
let kVTCompressionPropertyKey_ConstantQualityFactor: CFString
```

## Discussion

Discussion Requires the encoder to maintain consistent quality by specifying a target constant quality factor in the range of 0.0 to 1.0. In contrast to cases where kVTCompressionPropertyKey_Quality will cause the quantization parameter to adhere to a fixed value, this property is designed for consistent visual quality with or without bitrate limit constraints. 0.0 is the lowest quality and 1.0 implies the highest quality possible.