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Ed's AV Handbook
Batting Practice for the AV Professional
and primer for the novice

Chapter 4  Page 9

Video Reproduction
The UltraHD WCG HDR HDMI Pipeline

UltraHD's Wide Color Gamut via High Dynamic Range is an HDMI pipeline of competing formats and specifications.  It must be carefully navigated.  Lack of compliance leads to blank, intermittent, noisy, or downgraded images.  Select the TV, video sources, receiver/preamp, and interconnecting cabling with care

Natural life-like images
HDR TV Screen

High Dynamic Range + Wide Color Gamut

High Dynamic Range (HDR) expands the difference between black and the brightest white light.  It creates a grayscale that allows for the simultaneous display of brighter-highlights and darker shadow detail.  HDR provides a dynamic window for the expansion of color.

Wide Color Gamut (WCG) extends the range of color via 10-bit and, eventually 12-bit, color depth.  Partnered with HDR, WCG provides more shades of color.  10-bit WCG expands the color range from HDTV's 16.7 million colors to over one billion colors.  12-bit WCG color will further expand to over four billion colors. 
The partnership of WCG and HDR is a breakthrough that produces more natural-life-like images. 

HDR Formats 

High dynamic range is the initial step in UHD-WCG-HDR-HDMI video pipeline.  However, HDR is available in many formats.  This is a concern because the video source HDR format dictates the decode format required by the final pipeline step, the TV or projector.  The following lists the current leading HDR formats.


HDR 10-bit color combines the SMPTE HDR & Consumer Technology Association HDMI 2.0a standards.  HDR10 is the current de-facto baseline format for all UltraHD HDR televisions. 
HDR10 employs static gamma as opposed to the dynamic metadata EOTF process used by more advanced formats.

Dolby Vision
Dolby Vision currently offers 10-bit color with a future path to 12bit color.   (Current TVs are limited to 10bit color.)
When implemented, 12bit color will increase the color palette from one to four billion colors. 
Dolby also engages dynamic metadata EOTF frame by frame correction. 

Hybrid Log Gamma (HGL)
HGL is a metadata EOTF broadcast standard format promoted by the BBC and NHK. 
It is also backward compatible with older Standard Dynamic Range (SDR) broadcasts.

Samsung HDR10+ upgrades HDR10 to EOTF correction as Dolby Vision and HLG. 

Technicolor HDR-2-U Advanced
SL-HDR1 includes hidden HDR data that allows for a simultaneous SDR HDR broadcast.
SL-HDR2 is a HDR10 based format that adds metadata EOTF. 
SL-HDR3 is a HLG based format that also adds metadata EOTF.

High Definition Multimedia Interface 
HDMI Versions 1.4 to 2.1

HDMI is the UltraHD WCG HDR pipeline interconnect that includes encryption to impede copying. 
All connected components and interconnects must meet the HDMI specs. 


HDMI is a system of interconnect cable, dedicated termination, plus encryption software. 
The HDMI software, embed in integrated chips, consists of three types -- source, repeater, and sink.

Source Data
Source data embeds in BluRay players, media severs, Internet streaming devices, cable boxes, and satellite receivers.

Repeater Data
Repeater data embeds in AV receivers, plus any form of video switching.

Sink Data
Sink data embeds in televisions and projectors.

Each HDMI chip rings software between connected HDMI chips.   If a source and sink HDMI chip connect, then the chips ring and respond to each other.  If a repeater inserts between the source and sink, then the repeater chip must also respond to the HDMI source and sink.  Each HDMI chip seeks confirmation from all connected devices.  An incorrect response, negative handshake, will result in noise, intermittent images, blank or downgraded screen images.

The following lists the specifications and video compatibility of HDMI versions 1.4 through 2.1.
Each version is compatible with the previous version.

HDMI 1.4 & 1.4a
- High Definition 1920 x 1080
- 18Gbps bandwidth with audio return and Ethernet channels.
- 1.4a adds 3D support.
Recommend 'High Speed' cable

HDMI 2.0
Adds Support for:
- UltraHD 3840 x 2160p resolution.
- 18Gbps @ 60fps
Recommend 'Premium High Speed' cable.

HDMI 2.0a

Adds Support for HDR10
Recommend 'Premium High Speed' cable.

HDMI 2.0b
Adds Support for:
- Up to 32 channels digital audio.
Recommend 'Premium High Speed' cable.

HDMI 2.1
Adds Support for: 
- UltraHD @ up to120fps
(enables virtual reality)
- UHD-8K @ 60fps
- 48Gbps bandwidth
- HDR10+
- Dolby Vision HDR
- 192kHz 24bit audio (lossless DTS)
- E-ARC (enhanced audio return channel)
Must use 'Ultra High Speed' cable.

The Gorilla in the Screen 

The jury is still out regarding final UltraHD/UHD-8K WCG/HDR implementation. 
Component and interconnect compatibility is
poised to create installation havoc. 
Therefore prepare installations with a 4 part plan.

1. Provide physical paths for upgrading cable.
2. Seek components that provide HDMI upgrades.
3. Study each component's setup menu for proper implementation.
4. Inform early adopters they may have to replace key-components sooner than expected. 

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Ed's AV Handbook   
Copyright 2007 Txu1-598-288 Revised 2021

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