# Chroma Location Extension Constants Constants that identify chroma location extensions. ## Topics ### Constants [`let kCMFormatDescriptionChromaLocation_Bottom: CFString`](/documentation/CoreMedia/kCMFormatDescriptionChromaLocation_Bottom-swift.var) The chroma sample is horizontally centered, but co-sited with the bottom row of the luma samples. [`let kCMFormatDescriptionChromaLocation_BottomLeft: CFString`](/documentation/CoreMedia/kCMFormatDescriptionChromaLocation_BottomLeft-swift.var) The chroma sample is co-sited with the bottom-left luma sample. [`let kCMFormatDescriptionChromaLocation_Center: CFString`](/documentation/CoreMedia/kCMFormatDescriptionChromaLocation_Center-swift.var) The chroma sample is fully centered. [`let kCMFormatDescriptionChromaLocation_DV420: CFString`](/documentation/CoreMedia/kCMFormatDescriptionChromaLocation_DV420-swift.var) The Cr and Cb samples are alternately co-sited with the left luma samples of the same field. [`let kCMFormatDescriptionChromaLocation_Left: CFString`](/documentation/CoreMedia/kCMFormatDescriptionChromaLocation_Left-swift.var) The chroma sample is horizontally co-sited with the left column of the luma samples, but centered vertically. [`let kCMFormatDescriptionChromaLocation_Top: CFString`](/documentation/CoreMedia/kCMFormatDescriptionChromaLocation_Top-swift.var) The chroma sample is horizontally centered, but co-sited with the top row of the luma samples. [`let kCMFormatDescriptionChromaLocation_TopLeft: CFString`](/documentation/CoreMedia/kCMFormatDescriptionChromaLocation_TopLeft-swift.var) The chroma sample is co-sited with the top-left luma sample. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)