Talk about the development of HDMI fiber optic cable from HDMI1.0

[Home Theater Network HDAV.com.cn] Compared to the traditional HDMI copper cable, HDMI fiber cable can be said to be good news in the near future. In the face of constantly refreshing data and records, as a crowd of people, my first thought is whether to throw away the HDMI cable at home and enjoy the achievements of emerging technologies. Fortunately, the balance of Cary stopped me in time. ... also let me calmly think about the following questions:

Is there any technical upgrade of the HDMI fiber optic cable compared to the traditional HDMI copper cable? Is there a clear difference in the specific audio and video output?

What are the basic shortcomings of HDMI fiber optic cable? Is it practical for ordinary families?

How many brands are currently producing HDMI cables on the market? Will the quality be uneven?

Where is the future of HDMI fiber optic cable? Will it replace the traditional HDMI copper wire?

If you have similar confusion, then this issue of HDMI fiber optic line is simply for you!

Before I introduce the HDMI fiber optic cable, I think it is still necessary to start with HDMI. The interface before HDMI is DVI (Digital Visual Interface), which was born to meet the needs of high-quality image transmission, but with the further development of audio-visual technology, DVI is generally compatible with flat-panel TVs and can only transmit 8bit signals. Problems such as not supporting digital audio signals are beginning to be unbearable. As a result, Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson, and Toshiba began to seek more advanced interface technologies, jointly formed the HDMI high-definition multimedia interface organization, and officially released HDMI 1.0 on December 9, 2002. Version standards, HDMI technology officially entered our sight.

Compared to DVI, the most obvious advantage of HDMI is the ability to simultaneously transmit video and audio signals. Only one HDMI connection is required between the player and the display device. From a technical perspective, the starting point of HDMI is also very high. In the past 15 years, from HDMI 1.0 to HDMI 2.1, almost all of them are at the forefront of audio and video technology. Below, we will briefly review the development of HDMI over the past 15 years.

In 2002, the earliest HDMI version of HDMI 1.0 was introduced, with a maximum bandwidth of 4.95Gbps. The video supports DVD and Blu-ray, Rec.709 color gamut, and audio supports 8-channel PCM and 24-bit/192kHz audio sources. Can support 1080p full HD resolution and 7.1 sound system.

In 2004, HDMI 1.1 added support for DVD-Audio.

In 2005, the HDMI 1.2 version added the DSD lossless format to the support list.

In 2006, HDMI 1.3 version increased bandwidth to 10.2Gbps, supported xvYCC wide color gamut, and unlocked new audio technologies such as Dolby TrueHD and DTS-HD MA. Later, small changes such as 1.3a, 1.3b, 1.3b1, and 1.3c were introduced. In the same year, the world's first Blu-ray player, the Samsung BD-P1000, was already equipped with an HDMI interface.

In 2009, the first HDMI version of HDMI 1.4 supporting 4K 30p and 3D was introduced, and a new 100Mbps network transmission function was added.

In 2013, HDMI 2.0 increased bandwidth from 10.2Gbps to 18Gbps, supported 4K 60p and is compatible with Rec.2020 color depth. The audio side began to support 32-channel audio sources.

In 2015, HDMI 2.0a added support for HDR, and HDMI 2.0b added support for another high dynamic range technology HLG.

In 2017, HDMI2.1 will increase the bandwidth to 48Gbps, support 8K/60Hz, 4K/120Hz format video, 16bit color depth, and can transmit dynamic HDR data, which is Dolby Vison. Currently the most popular HDR10 is based on static metadata, using a set of data to control all the scenes and scenes, while dynamic metadata based Dolby Vison is much more accurate, it is adjusted for each frame of each scene, so that all the pictures Can show the most natural best state.

At present, display devices and players that support HDR content are generally equipped with HDMI 2.0a interfaces. After all, HDMI 2.1 is more ready for future formats. 4K has not yet become popular, and 8K? 120Hz, 16bit are similar. . The content of Dolby Vison is there, but it is rare. Microsoft's latest home console, xbox one x, is probably the world's first device with an HDMI 2.1 interface.

Copper wire VS fiber optic cable

From HDMI 1.0 to HDMI 2.1, which has not yet been officially put into use, the resolution and frame rate of the signal are increasing, which means that the total amount of data of the signal is also increased. The total amount of data of the 4K signal is four times that of 1080p. If you think of a wire as a pipe, it means you need a bigger pipe to transfer data. The conductivity of our traditionally used HDMI copper wire is basically determined by the number of copper wires. The more copper wires, the better the conductivity, that is, if the total amount and speed of the transmitted signal increase, the size and weight of the copper wire. It must also be increased. Friends who have used HDMI copper wire should know the real weight. From the perspective of daily use, it is really not convenient.

The biggest disadvantage of HDMI copper wire is that it can't transmit over long distances. Once the distance exceeds 10 meters, it will produce loss. The faster the signal transmission speed, the greater the attenuation, which may cause problems such as signal loss or resolution degradation. The "hard" of metal conduction. Generally speaking, the bandwidth of HDMI copper transmission of 18Gbps is difficult to exceed 12 meters, then the transmission bandwidth of 48Gbps, 56Gbps or more? The wire is too short, the scope of application will be severely limited, for a relatively large private theater Or commercial or office space, HDMI copper wire seems to have some "more than enough power", this time requires a lighter, thinner, longer HDMI cable, in this technology development and market demand, HDMI Fiber optic lines came into being.

At present, the HDMI fiber-optic line on the market basically adopts the structure of fiber-optic plus copper wire, and the copper wire is electrically conductive, and the signal is transmitted by the optical fiber, and the photoelectric conversion is required from the signal source to the display device. Its advantage is that the fiber itself is very slim and light, and the HDMI cable only needs to use a few to achieve the purpose of transmitting large-capacity signals, so the weight of the wire is greatly reduced, basically only 60% of the copper wire, and the most important Yes, the loss per kilometer of fiber transmission is almost negligible, and electromagnetic interference is avoided, that is, the problem of long-distance transmission of HDMI lines is solved. But this does not mean that the HDMI fiber optic cable is perfect, because the built-in photoelectric conversion circuit, so the wire itself consumes electricity, if the voltage is reduced, it will affect the picture quality, such as the picture does not look bright enough, the contrast is reduced or the noise is significantly increased, etc. If the temperature of the conversion circuit is too high, the stability of the wire will be affected. HDMI copper wire will not have these problems. In terms of compatibility, copper wire also performs better than fiber optic cable. In other words, at present, short-distance transmission within 3 meters, it is basically difficult to replace the copper wire with the optical fiber. But it will not be necessary until the era of high bandwidth in the true sense.

The future trend

In general, the number of HDMI fiber optic lines currently on the market is very limited, mainly based on 18Gbps bandwidth. Supporting 4K 60p content should be the most basic requirement, but some wires have not been tested by ourselves. I don't know if it can really use the highest specification of 18Gbps. There is also a question mark in terms of transmission, stability and fluency. From the parameter information, we can also find that there is no small difference between them. For example, it does not support Rec.2020, 12bit or HDR content. The longest transmission distance is between 100-200 meters, and the degree of bending can withstand. Different from the angle, the length of the selected wire is different, and the price is not small. The price of HDMI fiber optic cable is basically more than 1,000 yuan, unless the wire is very short. However, if it is transmitted over a short distance, as far as the current situation is concerned, the optical fiber line is not superior to the copper wire. HDMI copper transmission 18Gbps bandwidth, there is no obvious loss problem within 12 meters, even if the projector is hung, put the signal source below, it should be more than enough to connect with 12 meters long, unless you want to connect across the room. . With this in mind, although many HDMI fiber-optic cables can be transported over 50 meters or even 100 meters long, it seems that there is no practical use for ordinary home environments...

In the face of the most mainstream 18Gbps bandwidth, the advantage of long-distance transmission of HDMI fiber-optic lines is not enough. But the future is not necessarily the case. We can simply make an algorithm. The transmission limit of HDMI copper wire is 35 meters (plus amplifier), and it is better not to exceed 12 meters under 18Gbps bandwidth. Otherwise, it is easy to be limited in terms of applicability. For example, connecting a projector can transmit pictures. TV as a display device will not work and so on. The incoming 48Gbps is about 2.6 times that of 18Gbps. HDMI copper wire wants to transmit such a large amount of data. It must use more copper wires and shorten the length to enhance the conductivity and reduce the loss. It is conceivable that the HDMI copper wire will definitely be limited in weight and length. It is expected to be 2-3 meters in length. If the projector is used at home, the length is definitely not enough. The HDMI fiber cable itself does not have the problem of bandwidth limitation.

Of course, I did not immediately assume that the HDMI copper wire was sentenced to death. It can reduce the resistance by silver plating, reduce the loss, or how to isolate the line from the line, reduce interference and other methods to defend their position, but No matter how improved, the nature of metal conduction will not change. The problem that the optical fiber may cause insufficient voltage and high temperature can be solved by improving the performance of the photoelectric conversion chip. As for the price issue that everyone is most concerned about, the length of the fiber optic cable is only more than 2 meters, and the price is basically more than 1,000 yuan. The longer the more expensive, the more the fiber optic cable has not really opened the market for mass production. It is only a matter of time to welcome the hundred yuan era. Moreover, at present, high-performance copper wires exceeding 10 meters and 15 meters are not much cheaper than fiber-optic wires. We have every reason to believe that the fiber optic cable is the trend of the future.

Someone once commented on the current HDMI 2.1, just like building a 10-lane road in the middle of the countryside, which is of no use. In the same way, now is only the 1.0 era of HDMI fiber optic cable. To make ordinary users aware of the superiority and necessity of HDMI fiber optic cable, it is sure to need more high-quality and high-quality content support. When users find that traditional HDMI copper cables can't transmit audio and video content well, they will naturally embrace the HDMI fiber optic cable. The upcoming HDMI 2.1 may be the watershed of the official distance between HDMI copper and fiber. As for the difference between audio and video performance between HDMI copper wire and fiber cable and different fiber cable, it is another level. Some people regard the replacement of wire as a "metaphysics". Can changing a line really bring about changes in image quality and sound quality? Or is it just a psychological suggestion?

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