This article covers

• Components
• Video infrastructure
• Video I/O settings
• Viewing environment
• Potential setups
  • Single monitor setup HDR/SDR using an iCMU
  • Dual monitor setup HDR - SDR using an iCMU
  • Dual monitor setup HDR - SDR using an eCMU
•  HDMI extenders

for setting up a color grading or mastering suite for Dolby Vision workflows aiming to deliver Dolby Vision mezzanine files (PQ) to OTT service providers.
 

Components

Required:

• A Color corrector that supports Dolby Vision – check all supported system here
• An HDR reference display that may also be used as your SDR reference monitor – read more about monitors in this article

Optional:

• Dolby Vision mastering and playback license – to unlock the trim controls inside your color corrector or mastering tool – request a license here
• External Content Mapping Unit (eCMU)
• SDR reference display
• HDR (client) consumer display (TV)
• Dolby Vision (client) consumer display (TV)
• External scopes

Video infrastructure

Dolby Vision - using the PQ EOTF - was designed to process the highest quality video throughout the content creation process, and it is therefore recommended to have video infrastructure that fully supports 12bit, RGB, full range (SDI full) video across the facility. It is important to output this highest quality video from the color corrector or mastering system, and subsequently have suitable mastering and target displays setup to receive and display this content correctly.
 

HDR and SDR video inputs and outputs

HDR - ITU-R BT.2100 PQ

HDR – P3 PQ

SDR - ITU-R BT.709 (to be displayed on an ITU-R BT.1886 compliant display)

Viewing environment

A proper viewing environment should consist of a calibrated display, appropriate seating for the observer relative to the display, as well as proper lighting and room decor.
 

• Surround illumination: the area around the screen should be illuminated using a light source and reflective surface that matches the chromaticity reference white point characteristics of the display in use, i.e., D65, for both HDR and SDR.

• Surround light level: 5 nit (for HDR and SDR)

• Surround area extent: min. 90 degrees horizontal field of view and min. 60 degrees vertical field of view from the observer.

• Viewing distance: HD: 3x – 3.2x picture height, UHD: 1.5x – 1.6x picture height

• Room decor: should be of neutral matte materials without dominant colors or distracting images and patterns.

Fig.1: Horizontal Field of View for Reference Display Surround Area



Fig. 2: Surround illumination

Further, it is recommended to allow an observer at least 10 minutes to adapt to the viewing environment, especially when walking into the room (or suite) from a brighter environment or the outdoors.

Check SMPTE ST 2080-3 for more detailed info.

 

Potential Setups using SDI and HDMI infrastructures

Single monitor setup HDR/SDR using an iCMU

Master and Target Display setup

In such a setup, we will be using the same monitor as the HDR (master/target) display and SDR (target) display. In order to quickly and conveniently switch between the different modes, we recommend setting up monitor input/output presets for the required settings.
 

Client Display – HDR/SDR Consumer Television

If a larger display is required for client viewing, the output of the iCMU can be displayed on an HDR capable consumer television over an HDMI link. This will usually require an SDI to HDMI converter (like the AJA Hi-5 4K Plus).

Note:

It is important to ensure that such convertors do not clip or limit the signal range from full to legal, and preserves the quality and integrity of the original signal.

Further, when using such a display to view an HDR/PQ image, you must set the consumer HDR TV to its “absolute PQ mode” [without applying any (static) metadata]. When viewing an SDR/Rec.709 target, the TV must be set to its SDR, Rec.709 mode with a max. luminance of 100 nit.
Consumer TVs should be properly calibrated so that their HDR and SDR modes visually match your mastering monitor as much as possible.
 

Dual monitor setup HDR - SDR using an iCMU

Master and Target Display setup

Some colorists prefer to work while viewing the HDR master and the derived SDR simultaneously on two separate displays. Also, some QC operators use such dual monitor setups to perform a visual QC in HDR and SDR at the same time.
Using dual display setups, we highly recommend that the HDR and SDR display:
 

• Use the same display technology (e.g., both OLED, or both LCD)
• Have the same display size
• Are, ideally, the same make and model

Additionally, the recommendations for master/target reference displays as well as HDR/SDR client displays apply as described above.

 

Note:

To output HDR and SDR simultaneously, the video board of your color corrector or mastering system must support at least twice the resolution you’re aiming to output. E.g., if you want to output HDR and SDR simultaneously at a resolution of 1080p (HD), the video board must support a resolution of least 2160p (UHD).

Dual monitor setup HDR - SDR using an eCMU

eCMU setup

**The Dolby eCMU was discontinued in early 2024, and there will be no further updates provided for this product.

The eCMU performs the Dolby Vision content mapping function, on content with embedded Dolby Vision metadata, sent from a color correction or mastering system over an SDI interface. The mapped output from the eCMU is finally sent out, over SDI, to an appropriate SDR/HDR target display. In addition to the SDI link, the color correction or mastering system must also communicate with the eCMU via an ethernet network; connected directly or as part of a larger house network. This data network traffic is minimal and generally only used at startup or during project initialization.

 

Master and Target Display setup

The same recommendations for master and target display as described above, apply.

 

Client Display – HDR/SDR Consumer Television

The same recommendations for client display as HDR/SDR TVs apply.

If your client display supports Dolby Vision, you may want to use the HDMI tunneling functionality of the eCMU, which is also supported via the iCMU on selected color correctors and mastering tools.
For a comprehensive list of systems and tools supporting HDMI tunneling please see this link and check this article on how to use the HDMI tunneling feature.

 

HDMI extenders

As most workstations as well as external CMUs (eCMUs) are located in a dedicated server room, usually quite far from the suite itself, distance is an important factor to consider when designing your grading or mastering suite. HDMI's transmittance is limited by distance, more so than other cables like SDI.
In order to preserve Dolby Vision metadata over HDMI (when using HDMI tunneling) it’s crucial to check that the HDMI extender supports the transmission of Dolby Vision metadata. Please check your vendor's latest offerings on their latest Dolby Vision integration.