Learn the HDMI 2.1a specification in one article: enhance the HDR display effect

The HDMI Licensing Administrator (hereafter referred to as HDMI LA) introduces an updated version of the HDMI 2.1a standard specification, which introduces a new source-based tone mapping (SBTM)-HDR feature that can enhance and optimize HDR displays.

In addition, the SBTM function can automatically generate an optimized HDR signal to better utilize the monitor's HDR capabilities. This process does not require users to manually set up, which can greatly improve the PC and gaming experience.

HDMI LA also connects with domestic media online to conduct in-depth exchanges on the new features of the HDMI 2.1a specification.

HDMI shipments exceed 11 billion units

First of all, Rob Tobias, CEO and President of HDMI LA, shared that HDMI has shipped more than 11 billion units in the past 20 years. In fact, the versatility of HDMI is constantly increasing, and the new MacBookPro also supports the HDMI interface. Even in the auto industry, luxury SUVs are equipped with HDMI cables.

4K TVs continue to grow steadily, especially as games continue to innovate and 4K content becomes more popular. 4K and 8K UHD TVs can achieve a 23% growth rate. Displays achieved an 83% growth rate. The addition of HDMI 2.1 continues to maintain this growth rate.

From 2020 to 2025, 8K device shipments will grow by more than 400%, and it is expected that all 8K TVs will account for more than 20% of all 8K TVs in China, Europe, and the United States this year.

Last year's Olympic Games also included 8K content broadcasting for the first time, and now more and more retailers and distributors are promoting and promoting 8K TVs. HDMI LA products have been certified to support HDMI 2.1 8K functions, and it is believed that its growth will be quite promising in 2022.

HDMI 2.1a Core New Function: SBTM

SBTM, tone mapping for source transmission. HDMI 2.1a introduces source-based tone mapping, a new feature of HDR. In addition to monitor tone mapping, it also allows the source device to perform some HDR mapping, a feature that allows the source to send out a video signal and adjust its output to take full advantage of the HDR capabilities of a specific monitor to make the best use of each display potential.

SBTM enhances new HDR capabilities for HDMI-enabled products, further enhancing consumers' high-quality viewing experience.

So why update the HDR specs? Not all monitors have the same HDR capabilities, and some monitors have a different range of color and brightness levels than others. This is no problem when sending HDR video like HDR 10 and HLG because TVs often map HDR content beyond the display's capabilities to the range of available brightness and color.

But sometimes, the source device needs to combine different types of content at the same time, such as HDR, SDR, Dynamic HDR, graphics. For example, when you look at a streaming video service's menu of video thumbnails, some thumbnails may be HDR, others may be SDR, and the menus are rendered in graphics, which are projected to the display at different sources. On the other hand, the distinguishing ability of the display will be slightly different.

When a source device combines different types of content, SBTM enables the source to send the video signal to exploit the potential of each display by adjusting its output to take advantage of the SDR, HDR and Dynamic HDR capabilities of a particular display.

Like other HDR technologies, SBTM can adapt a source to a specific display, rather than adopting a fixed set of color and brightness ranges. SBTM also enables PCs and gaming devices to automatically process HDR-optimized signals.

It is worth noting that all types of set-top boxes can use SBTM, and many devices can be upgraded to support SBTM firmware. To activate SBTM, both the transmitting device and the receiving device must support the SBTM function.

Of course, around the popularization of new technologies, the media also raised more detailed questions. Rob Tobias, CEO and President of HDMI LA, and Chandlee Harrell, President of HDMI Forum, answered one by one.

How compatible is SBTM?

Question: Terminal manufacturers generally have their own HDR algorithms, and the resulting effects are also different. Can SBTM be compatible with and match all HDR specifications?

Chandlee: There are many different HDR specifications on the market, and SBTM has been designed for different specifications to ensure that it is compatible with HDR of these specifications. The launch of this function will also be tested by the authorized test center ATC before it can be implemented.

Can an old PC experience SBTM?

Q: I just mentioned that SBTM can support PC, can old PC also? Is support via software upgrades or is it only supported on newly released PCs?

Chandlee: PCs can indeed support SBTM. About how old PCs can support SBTM. First, it can be supported through software updates. Second, because there is a graphics card in the PC, the graphics card needs to be updated by classification.

It should be emphasized that different PC manufacturers may have different practices, technologies, and plans. Therefore, to be on the safe side, it depends on different PC manufacturers, such as Lenovo and Acer. It is best to refer to the official website. How to support this technical.

But for sure, SBTM can support PC, because its main emphasis is on the source side.

Can the HDMI 2.1 specification be further popularized?

Q: HDMI 2.1 has been launched for a long time, and now many products have been popularized. But compared with the popularity of some entry-level TV monitors, what kind of strategy will HDMI have to promote the full popularity of HDMI 2.1?

Rob: HDMI 2.1 has various functions. Regarding high-end products, TVs such as 4K120/8K60 have gradually become popular. In fact, many entry-level models can be equipped with ALLM, VRR, and eARC. These features don't necessarily have to support 8K, but are only options for entry-level TV or monitor manufacturers. In fact, whether it is entry-level or high-end, it depends on the functions provided by the chip manufacturer. With the gradual popularization of HDMI 2.1 functions, the chip functions will also gradually become popular.

If the price of the chip drops, it will also drive various entry-level TVs to adopt various HDMI 2.1 functions. Even as the chip price falls, entry-level TVs will also be equipped with 8K resolution, allowing consumers to enjoy higher definition at a closer price.