In 2018, there are many new changes in the field of HDMI cables. First, with the major promotion of major HD video cable manufacturers, HDMI Active Optical Cable (AOC) is more and more cost-effective and become more and more popular, but some people still do not know what HDMI AOC is. Second, after the HDMI 2.1 standard is released, it is reported that the first HDMI 2.1 HDMI cable is expected to appear this year. In the face of HDMI video cable material changing from copper to optical fiber, as well as the constant updating and development of standards, do you understand them? Are you going to replace the HDMI copper cable and enjoy the latest technological achievements? If you do not understand, if you haven't changed, then reading this article may solve your confusion .
Before we begin to analyze the development of HDMI AOC in depth, we first need to understand the evolution of HDMI standards and the impact of these standards. Let's briefly review the development of HDMI in the past 15 years.
1) In 2002, the earliest version of the HDMI, HDMI 1.0, was released. Its maximum bandwidth is 4.95Gbps. It supports DVD and Blu-ray, Rec.709 gamut by video, and supports 8 sound channel PCM and 24bit/192kHz sound source by audio. That is, it has been able to support the 1080p full HD resolution and 7.1 sound system.
2) In 2004, HDMI 1.1 added support for DVD-Audio. In 2005, the HDMI 1.2 added the DSD lossless format to the support list.
3) In 2006, HDMI 1.3 increased bandwidth to 10.2Gbps. It supports xvYCC wide gamut, and unlocked Dolby TrueHD and DTS-HD MA. After that, a series of minor modifications such as 1.3a, 1.3b, 1.3b1 and 1.3c were released. In the same year, the world's first Blu ray player Samsung BD-P1000 was launched with HDMI interface.
4) in 2009, the first HDMI version HDMI 1.4, which supports 4K 30p and 3D, came out and added 100Mbps's network transmission function.
5) In 2013, HDMI 2.0 increased the bandwidth from 10.2Gbps to 18Gbps, supporting 4K 60p and compatible with Rec.2020 color depth. It supports the 32 channel sound source.
6) In 2015, HDMI 2.0a increased its support for HDR, while HDMI 2.0b added support for another high dynamic range technology HLG.
7) In 2017, HDMI 2.1 increased the bandwidth to 48Gbps, supported 8K/60Hz, 4K/120Hz format video, 16bit color deep, and can transmit dynamic HDR data, that is, Dolby Vison. The most popular HDR10 is based on static metadata, using a set of data to control all pictures and scenes, and Dolby Vison based on dynamic metadata is much more accurate. It is adjusted for each frame of each scene so that all the pictures can show the most natural and best state. At present, the relevant equipment supporting the HDMI 2.1 standard has not yet appeared.
From HDMI 1.0 to HDMI 2.1 (has not been formally put into use), the resolution and frame rate of the signal are increasing, which means that the total amount of the signal is also increased (the total amount of the 4K signal is 4 times that of the 1080p). Considering the cable as a pipe, we need a larger pipe to transmit the data. The conductivity of the HDMI copper cable that we traditionally use is basically determined by the number of copper cables. The more copper cables there are, the better the conductivity is, that is, if the amount and speed of the transmission signal are increased, the size and weight of the copper cable will inevitably increase, and the users who have used the HDMI copper cable should know that the weight is not light. For daily use, it is really not convenient.
The biggest drawback of HDMI copper cable is that it can not support long-distance transmission. Once the distance exceeds 10m, the loss emerges. The faster the signal transmission is, the greater the attenuation is, which leads to the loss of signals or the decline of the resolution. This is the "hard injury" of metal conduction. Generally speaking, the distance of HDMI copper transmission at 18Gbps is very difficult to exceed 12m. How does it transmit 48Gbps, 56Gbps or larger bandwidth? The cable is too short, so its application will be severely limited. For the larger private cinema or business and office space, the HDMI copper cable appears to have some "lack of heart and strength". At this time, a lighter, finer, longer HDMI cable is needed. Under this technology development and market demand, HDMI AOC emerges as the times require.
At present, the HDMI AOC on the market basically uses optical fiber and copper wire, conducting over copper wires and transmitting signals over optical fibers. It is necessary to undergo two photoelectric conversion from signal source to display device. Its advantage is that the optical fiber is very thin and lightweight, so the weight of the cable is greatly reduced, basically only 60% of the pure copper cable, and the most important thing is that the loss of fiber transmission per kilometer is almost negligible and the electromagnetic interference is avoided, that is to say, the problem of long distance transmission of the HDMI cable is solved. But this does not mean that HDMI AOC is perfect because of the built-in photoelectric conversion circuit, so the cable consumes electricity. If the voltage is reduced, it will affect the quality of the picture, such as the appearance of the picture is not bright enough, the contrast is reduced or the noise is obviously increased, and so on. However, the copper HDMI cable does not have these problems. In other words, at present, for the short distance transmission within 3m, the active optical cable will not replace the copper cable until the true sense of the high bandwidth era is coming.
So far, the number of HDMI AOC on the market is very limited, the price of long distance HDMI AOC is basically more than US$150, but at present, there are also manufacturers such as TYfiber (a Gigalight company), offering cost-effective HDMI AOC products. Basically, the TYfiber HDMI AOC products within 15m to 30m are less than US$150. At present, the advantage of 18Gbps HDMI 2.0 AOC can support long-distance transmission is not impressive enough. But it is uncertain in the future. We all know that the limit transmission distance of HDMI copper cable is 35m (with amplifier), and is better not more than 12m at 18Gbps bandwidth, otherwise its applicability would be easily limited. And for the following 48Gbps, about 2.6 times the 18Gbps, when the HDMI copper cable transmit such a large amount of data, it is sure to use more copper, and length should be shortened to enhance conductivity and reduce wastage. It can be imagined that the HDMI copper cable must be very limited in weight and length. It is expected to be 2m to 3m in length, and the length is not enough if the projector is used on the ceiling. Luckily, the HDMI AOC does not have the bandwidth limitations.
So, we can make a summary. Problems such as insufficient voltage and high temperature caused by HDMI AOC can be solved by improving the performance of the photoelectric conversion chip. As for the price problem that you are most concerned about, some excellent HD video optical interconnect manufacturers have solved already. Take the TYfiber for example, its HDMI 2.0 AOC within 30m is basically less than US$150. For this length, the high performance HDMI copper cable within 10m or 15m is not much cheaper than the HDMI AOC. We have reason to believe that the HDMI AOC is the trend of the future.