Dolby Vision CMv4

Dolby Vision CMv4

Introduction

Dolby Vision CMv4 (Content Mapping version 4) is the latest HDR profile released in 2021. It refines dynamic metadata schemas and tone mapping algorithms to support wider color gamuts, higher nit ceilings, and more efficient streaming.

Key Enhancements

• Expanded nit range: Supports mastering up to 10,000 nits and display adaptation down to 400 nits.
• Improved dynamic metadata: Finer granularity for scene‑by‑scene and frame‑by‑frame adjustment.
• Color gamut mapping: Enhanced algorithms for Rec.2020 to Rec.709 downconversion.

Implementation in Production

Content creators export two streams: a base layer and a dynamic metadata enhancement layer. CMv4 metadata attaches via SMPTE ST 2094 metadata sets, guiding playback devices in real time.

Benefits and Adoption

• Superior highlight retention and shadow detail across device types
• Reduced banding through updated quantization methods
• Broad support across streaming platforms (Apple TV+, Netflix)

Trivia

• CMv4 was first adopted in the Dolby Vision release of The Mandalorian Season 2.
• The specification spans over 200 pages in SMPTE documentation, reflecting its complexity.