Expected reading time: 4 minutes 

Summary: 

This article addresses the technical behavior of NCLC (Non-Colorimetric Light Code) metadata tagging in SDR video files generated from Dolby Vision content mapping workflows using DaVinci Resolve Studio. It explains the tagging patterns—where Dolby Vision-derived SDR outputs are tagged as 1-2-1 while other SDR renders might default to 1-1-1 and discusses the resulting compatibility challenges with professional broadcast and QC systems that expect 1-1-1 SDR signaling. 

Who this is for: 

Colorists, mastering engineers, QC technicians, and post-production supervisors working with Dolby Vision delivery workflows. 

Background 

In professional video delivery, color space signaling is critical for ensuring correct interpretation of image data across playback and monitoring systems. The NCLC (Non-Colorimetric Light Code) triplet — comprising colorprimaries, transfer characteristics, and matrix coefficients — is used in video containers (e.g., MOV, MXF) to signal these properties. 

For standard SDR Rec. 709 content, the expected NCLC tag is 1-1-1: 

• Color Primaries = 1 (BT.709) 

• Transfer Characteristics = 1 (BT.709) 

• Matrix Coefficients = 1 (BT.709) 

However, in workflows involving Dolby Vision content mapping, DaVinci Resolve generates SDR outputs tagged as 1-2-1, where the transfer characteristic is signaled as SMPTE 240M (2) instead of BT.709 (1).  

The same behavior can be observed in HDR-to-SDR conversions using ACES (Rec. 709, BT.1886) in DaVinci Resolve Studio. 

In contrast: 

• SDR outputs from HDR to SDR conversions using DaVinci YRGB color management are typically tagged as 1-1-1 

While all variants may appear visually correct, professional broadcast infrastructure and QC tools often enforce strict metadata validation, rejecting files with non-standard compliant transfer characteristics — even when the pixel data is valid. 

Note: The 1-2-1 tagging in Dolby Vision-derived SDR outputs is not a requirement of the Dolby Vision specification. The resulting SDR image is still intended to conform to Rec. 709/BT.1886 viewing conditions and should be signaled accordingly for compatibility. 

1-2-1 Tagging 

To properly flag an SDR file derived by Dolby Vision content mapping inside DaVinci Resolve, set the Gamma Tag under the Advanced Settings to Rec.709: 

This will result in a properly 1-1-1 tagged output. 

Examples 

MacOs Finder tag information: