Both HDMI and DP interfaces have multiple stages of development, but when we pick out DP1.2 and HDMI 2.0 with similar speeds, we will find that the former was released in 2009 and the latter was released in 2013-2014.

Also in 2014, the DP protocol has been upgraded to 1.3, and the DP1.4 interface that has been used so far was officially released two years later.

Looking back at the present, the standard was released in 19, and DP2.0, which has been bounced for nearly two consecutive years, is said to be in the development stage and may be listed at the end of this year. It can be said that the dragon has never seen the end; the legendary HDMI 3.0 is still in formulating standards, in other words, it does not exist, and even the concept is not complete.

During this period, HDMI did have a replacement scheme, namely HDMI 2.1, which reached the standard of simultaneous transmission of 4K120Hz and other signals with a maximum transmission rate of 48Gbps, but compared to DP1.4 a few years ago, it is not good enough, and it is about to debut with a maximum rate of 80Gbps. The DP2.0 interface "strikes on dimensionality reduction".

So why does the HDMI interface always lag behind the DP interface by nearly a generation in performance? Why is HDMI so much more popular than DP? The author believes that these two phenomena are related to the characteristics of HDMI itself.

HDMI is widely used in televisions, players and other fields, and it is inseparable from its inheritance of VGA, DVI and other interfaces.

It sends picture information line by line, so the rate can be defined by the pixel transfer rate (Mpxps), which also results in the limitation of the maximum screen resolution and refresh rate of each generation version. Of course, the more general rate description method is now Bandwidth, which is the Gbps mentioned above.

This feature determines that it can replace the analog signal VGA, the previous generation of digital signal DVI and other interfaces, and it also has the new advantage of integrating audio signals.

For old equipment, it is easy to use it to transfer to new equipment; for new equipment, there is no need to add decoding modules with different transmission principles, which enhances the economy and versatility of using this interface, which is the basis for its popularization.

The huge influence of HDMI’s founders Panasonic, Toshiba, Sony, Philips, Special Arts and other companies, including major industry supporters, 20th Century Fox, Warner Bros., Disney, Samsung, etc., is also an important reason for its popularity.

Then the more fundamental answer is ready: most home audio-visual users, including the audio-visual industry, do not actually need such a high transmission bandwidth.

Take the current commercial screening of IMAX, for example, the resolution of its digital version is only around 4K, and the frame rate is still the standard 25 frames. In these areas, in our opinion, the "lagging" generation of HDMI is always sufficient. In the state, there is not so much pressure to upgrade.

The same example also appears in the field of home audio and video. Even in the field of Blu-ray playback (there is a common misunderstanding here, Blu-ray is not a picture quality but a way to read and write discs), the amount of video signal transmission after read and transcoded does not exceed the capabilities of HDMI, the reason is still the resolution and frame rate range within the industry standard.

From this point of view, HDMI has even made a compromise, leading the generation of "in line" in transmission capacity in response to the demands of more diverse display devices.

In terms of the DP interface, including the PC Alliance, the creator of DP, the environment is different. On the one hand, DP has faced display development from the beginning, adopting a "micro data packet" transmission architecture which is different from line-by-line transmission, so a new decoding module is needed.

On the other hand, unlike the audio-visual industry that pursues standardized presentation, the PC display field has always pursued higher display standards. This trend is also driven by user needs and advances in software and hardware, such as resolution, frame rate/refresh rate, HDR, and color depth. The parameters that we are familiar with are closely related to the interface transmission rate.

Therefore, DP is constantly being replaced by the advancement of the hardware level. There is even a dual DP line connection scheme between DP1.4 and DP2.0, which is not yet practical, to achieve the transmission rate of the 4K144Hz display standard.

Look forward to the future development of these two interfaces. Needless to say, DP, from the perspective of the DP2.0 standard, has set aside 3-5 years of performance redundancy that is not out of date, but it needs to be further popularized.

However, the lack of pressure of HDMI is still moving forward in small steps, and this phenomenon can also be understood. With the popularity of HDMI and the forces behind it, even if its performance is lagging, it will not be the reason for its replacement, but the opportunity for its large-scale replacement may only come with the large-scale update of the entire film, television, audio and video industry standards, which is different from DP.  It’s not a few PC enthusiasts that matter, but billions of TV users around the world. Taking the movie industry and home Blu-ray playback as an example, the industry’s traditional frame rate may remain unchanged for a long time.

However, the resolution adjustment space is unprecedented and even far beyond the field of PC display. The theoretical limit of the resolution that the top IMAX movie camera can shoot is up to 16K. After the film is digitally processed, it will be around 4K. If the industry believes that the future projection resolution and the new Blu-ray standard should be increased to 8-10K, I believe it will add little bargaining chips to the arrival of the next generation of HDMI.