HDMI Feature Definitions - Simplified

HDMI Feature Definitions - Simplified

HDMI specifications and features can seem very confusing and to what degree are they relevant anyway, when choosing cables to connect to your HDMI devices.

This article reviews each feature in the HDMI feature table and adds some explanation as to its meaning in simple and practical terms.

Full HD Blu-ray Disc and HD DVD video: will the HDMI cable transmit the full resolution from a DVD or Blu-ray player.

Consumer Electronic control (CEC): This feature allows (where supported by the HDMI version) you to use your TV remote to control some features of devices that are connected to your TV via HDMI, reducing the need for a universal remote control.

DVD-Audio: Shows which HDMI version supports Audio from source to display.

Super Audio CD(DSD): This shows which HDMI version will carry the Super audio (SACD) signals. Note that HDMI does not carry multiple SACD audio signals as would be required by home theatre.

Deep Colour: HDMI Deep Colour is a HDMI feature that enables higher than 8 bit fully upsampled chroma to be transmitted. The actual HDMI Deep Colour bit depth is determined by the HDMI transmt ' reciev chip set being used in the equipment connected by the cable. A key point is that whilst HDMI spec can support this feature the DVD and Blu-ray ROM spec doesn't. Chroma on these formats is 8 bit. The reality is it's a solution to a problem that doesn't exist i.e. a real film source containing greater than 8 bit chroma data. The only potential benefit is if the player performs a better job of video processing than the display. However many displays interpolate to higher than 8 bit anyway.

Auto lip sync: Auto lip sync means that the display receiver (TV) will tell the source connected by HDMI the length of time it takes to process the video, allowing the source to configure itself automatically. This feature in the table shows which HDMI version supports the feature but there appears to be many pieces of equipment that purport to offer auto lip sync but not in reality. The cable where correct in version can only handle what is presented and will not fix source and receive equipment if the facility is not present.

Dolby True HD / DTS-HD Master Audio bitstream capable:
DTS-HD Master Audio is a high-definition digital surround sound format developed by DTS for home theatre use. The format supports up to eight channels of surround sound with an increased dynamic range, a wider frequency response, and a higher sampling rate than other DTS surround formats. DTS-HD Master Audio is primarily used in the Blu-ray Disc and Ultra HD Blu-ray formats. A DTS-HD Master Audio signal using HDMI is transferred from a compatible source (such as Blu-ray and Ultra HD Blu-ray) through a DTS-HD Master Audio encoded bitstream, using HDMI (ver 1.3 or later), to a home theatre receiver with a DTS-HD Master Audio decoder. The receiver decodes the signal and passes it through its amplifiers to the speakers.

3D Video:
To connect 3D TVs with 3D Blu-Ray players you will need an HDMI cable that can handle 3D video. Best stick with HDMI 2 and above cables to be sure you have captured all nuances and get the 3D performance you are looking for.

Ethernet Channel:
The ethernet twisted pair cable ethernet cpabaility of the HDMI 1.4 and upwards cables is now used for Audio ARC and reduced no. device remote controller use (CEC) almost entirely, between TVs, players, theatre set ups and sound bars etc.

ARC (Audio return channel):
HDMI ARC facilitates audio to a TV and audio from a TV. If the TV is connected to an antenna feed or set top box feed, the audio from the TV can be distrubuted elsewhere to a soundbar or theatre set up via an HDMI cable ARC enabled. Conversely a Blu-ray player feeding the TV will supply the audio over the ARC channel on the HDMI 1.4 and above cable.

1920 x 1080 resolution at 120Hz refresh rate:
HDMI 1.4, 2.0 and 2.1 all offer 1080p resolution at 120 frame refresh rate and It is the easiest high resolution to hit at 120Hz and the hardware you'll need to achieve it is a relatively low bar too. The Xbox One X and S, and most gaming PCs of recent years can achieve this for some games. But you have have at least an HDMI 1.4 cable.
Generally, the higher the refresh rate the smoother the action will appear on screen. (There are other factors involved like what is the capability of the native source signal and other odd effects that might detract from a faster refresh rate in some cases.)

4K/8K resolution at 30/60/120Hz rate:
As above, but for a 4KTv only a 30Hz refresh rate is achievable with HDMI 1.4. For 60Hz refresh rate HDMI 2.0 is needed. Similarly, 4K at 120Hz need the HDMI 2.1 cable as does the 8K at 60Hz refresh rate.

4 audio and 2 video streams:
From HDMI 2.0 and upwards you can get up to four audio streams and two video streams over one cable.

Hybrid Log gamma (HLG):
Sounds complicated but relatively simple really. HDR Tvs can display Higher dynamic range content but there are many SDR (standard range TVs) still being used that cannot display HDR source. HLG is the answer that enables on source signal that can be used by bothe SDR and HDR TVs. If the TV is HDR enabled then it decodes the signals and displays accordingly. If the receiving TV is SDR then the HDR capability is ignored and a standard dynamic range piocture is displayed. HLG enables this. You need HDMI 2.0 cables to enable this feature from device to TV or other display.

Static HDR:
This is the metadata needed to be present to enable a full High Dynamic Range display that is HDR capable. Not all HDMI cables cater for HDR in this regard. HDMI 2.0 and 2.1 are compatible.

eARC (enhanced ARC):
How Is eARC Different From ARC?
eARC can carry up to 32-channel audio, including eight channels of 192 kHz, 24-bit uncompressed audio. It also supports DTS-HD Master Audio, DTS:X, Dolby TrueHD, and Dolby Atmos formats. Whereas ARC only supports up to six-channel compressed audio and has a maximum bandwidth of 1Mb/second.
In addition, eARC includes its own data channel that enables the TV to discover connected and compatible eARC audio devices. It is also used by the audio device to convey supported audio formats and enables the TV to send lip-sync correction data to the audio device.

Variable refresh rate (VRR):
VRR, or ‘variable refresh rate’, is a key feature enabling a smooth, artefact-free picture when gaming – giving a clean image for both offline and competitive games.
how does it work?
VRR exists to eliminate screen tearing when playing games. Tearing is a common visual glitch, where the image on your TV shudders mid-frame before carrying on as before.
Screen tearing happens when your TV refreshes its frame but where the image is out-of-sync with the rate at which  your signal source delivers frames. You end up with an image that, for example, the top half of the screen displays one frame and the bottom the next. 
This happens because TVs don’t refresh their entire screen image instantly. The driver of a display rapidly scans down the screen, from top to bottom, updating the state of each pixel. All this happens too fast for our eyes and brains to notice, until there is a visual screen tear or aberration. VRR largely sorts this out but needs an HDMI 2.1 cable from source to TV/display to enable this

Quick media switching (QMS):
QMS, the latest acronym in the TV world is relatively new and has yet to be fully made us of. But what does it actually do?
QMS stands for Quick Media Switching, and it's intended to eliminate the blank screen that flashes up when you switch from a signal that's being output in one frame rate to a signal in another. It does this by shifting the refresh rate in real time. HDMI 2.1 cables enable this feature when connecting signal source to TV.

Quick Frame Transport (QFT):
HDMI QFT stands for Quick Frame Transport and, like its name suggests, it's a technology that speeds up the transmission of each frame on its journey from source to screen. It decreases the latency between the moment when the visual data is available in the signal source output of your gaming device and the time when that data is then rendered on the TV screen as a frame. The shorter that gap, the closer your gameplay can be to the live version of the action. However both source and TV / screen need to be QFT enbaled for this to work and connected by an HDMI 2.1 cable.

Auto Low Latency mode (ALLM):
ALLM (Auto Low Latency Mode) is a simple little feature that is not likely to transform your gaming experience too much, but will improve the experience of living with a TV that's used for gaming as well as TV- and movie-watching. It's available in lots of TVs and existing consoles – even those that don't have HDMI 2.1 sockets.
ALLM automatically switches to the TV's gaming preset, or Game Mode, when a gaming signal is detected.

Display Stream Compression (DSC):
Compression in electronic terms is the squeezing of data so that it takes up less space. DSC for high resolution displays is necessary since display standards like DisplayPort 1.4 and HDMI 2.1 are limited to 32.4 Gbps and 48 Gbps respectively. The Use of DSC will allow higher resolutions and faster refresh rates on supported displays to be reached, moreover, some monitors require it in order to hit peak performance.
DSC is used in both the DisplayPort 1.4 and HDMI 2.1 standards. DisplayPort 1.4 can only support 4K resolution in HDR at 60Hz in full 10-bit color natively, but with DSC this is increased to 4K 120Hz (HDR) or 8K at 60Hz.
HDMI 2.1 takes it a step further, with support for 8K 60Hz in full 12-bit color natively, or 4K HDR at 120Hz in full 12-bit. But add DSC to the mix and you enable up to 10K 120Hz in 12-bit color, which would require nearly 3 x the HDMI 2.1 capability of 48 Gbps to run at 120.29 Gbps.
HDMI 2.1 and DSC provide the data, speed and refresh rates to support just about any combination of source and display available at the present time.

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