A new horizon for HDMI 2.1 – 8K

Allion Labs / Tina Yu

Regarding the new topic of 8K, it could trace back to that Japan mention 8K TV broadcast for 2020 Tokyo Olympics. Because of this topic, 8K TV is very on trend. The this year CES, the TV manufacturer SONY、Sharp、LG、Samsung、TCL promoted their own 8K TV. According to IHS Markit report indicated that the shipping of 8Kwas less than 20k units in 2018, but it will be up to 430k units until 2019. And in 2020, it will estimate to become to 2000k units. It shows 8K TV could bring the huge business in the future.

Sources from IHS Markit

4K TV is main specification in the market. You can have one by price lowering than USD$630. The HDMI interface is also one of the standard interfaces for each TV. At the end of 2017, the HDMI LA announced the latest specification Version 2.1, and the biggest highlight is the bandwidth is increased to 48Gbps, it made 8K is basic specification or even 10K. Therefore, the 8K era has been opened and it will speed up the elimination of 4K. In the future, 8K will be the basic equipment at the home.

There is still a technical level to overcome in the full implementation of 8K TV.

Undoubtedly, 8K TV become more and more popular in the future! However, there is still a long route to fully achieve 8K from real life. 2019 is the 8K beginning year, all TV manufacturers are actively developing their own 8K TV, although the HDMI 2.1 interface and its pin configuration is no different from the previous version, but the new 8K specification of HDMI 2.1 and the previous 4K of HDMI 2.0 are two different technologies, and it is more rigorous and more complex than the previous HDMI version.

Following figure is the table for HDMI specification comparison:

SignalHDMI 2.0HDMI 2.1
Max Bandwidth18Gbps48Gbps
AV ChannelD0, D1, D2L0, L1, L2, L3
CompressionDSC 1.2
Compatible with previous versionsYes(HDMI 1.4b)Yes(HDMI 1.4b, HDMI 2.0)

From the above table, the maximum transmission bandwidth of HDMI 2.1 has increased to 2.6 times that of HDMI 2.0. Therefore, in the existing framework, the transmission technology of the original TMDS and the encoding method of 8b/10b are not enough. Why? Let’s see what is TMDS?

  1. Transition Minimized Differential Signaling is short for TMDS. It is a high-speed transmission data technology developed by Silicon Image of the United States.
  2. This technology was first used on the DVI interface, and also used on HDMI interface.
  3. It is characterized by the technique of transmitting signals by using two pins as differential signals.
  4. And it was transmitting AV signal via 4 pairs TMDS channel(Clock, Data0, Data1, Data2).
  5. The TMDS Clock is only used to make the receiver use the reference frequency for data recovery. The actual AV signal is running on the other 3 pairs of TMDS Data channels.
  6. The 8b/10b is a encoding method that 8 bit input signal is converted into a 10 bit. The main purpose is to reduce the EMI and improve the accurate signal transmission rate through the differential signal.

Through the above characteristics, we can know that the bandwidth needs to be increased under the existing architecture which is not necessary to add a new data channel, but to transmit a higher amount of data in the existing three pairs of Data channels. But this is not the best solution. Therefore, the new FRL (Fixed Rate Link) transmission technology and the 16b/18b encoding method came into being, and its characteristics are as follows:

  1. Fixed Rate Link is short for FRL which means fixing its bandwidth.
  2. And TMDS Clock, Data 0, Data 1, Data 2 is correspond to FRL Lane 0, Lane 1, Lane 2, Lane 3。
  3. Similar to the Embedded CK mode of DP, because the dedicated Clock channel is not required, the AV signal can transmit not only 3 pairs of Lanes but even 4 pairs of Lanes.
  4. The coding of 8b/10b become to16b/18b that is improved the 9% coding efficiency.
  5. Adopt VESA DSC compression technology with resolution up to 10K@120.
  6. The transmission method different from DC-coupled TMDS has been converted into the transmission mode of AC-coupled FRL
  7. Communication through FRL Link Training is compatible with TMDS mode.

Therefore, how to meet the new FRL mode and be compatible with the original TMDS mode is a major issue for manufacturers developing HDMI 2.1 products.

Allion 8K Test Solution

In order to enable 8K TV manufacturers to quickly get the HDMI 2.1-compliant admission ticket, Allion actively cooperated with related instrument manufacturers to develop Allion’s SCDC controller (AJSC-1) integrated into the 8K related electrical test, as follows Test plan:

  •  8K Verification Test
    • FRL Electrical Test
    • FRL Protocol Test
    • 8K Video測試
  • HDMI 2.0 Compliance Test
    • TMDS Electrical Test
    • TMDS Protocol Test
    • TMDS Decoding Test
    • TMDS Video Timing Test
    • EDID related test
  • HDMI 1.4 Compliance Test
    • EDID/E-DDC Test
    • Electrical Test
    • Protocol Test
    • Video Test
    • Audio Test
    • Interoperability with DVI Test
    • Advanced Features

Allion Case Study

One of the problems with HDMI 2.1’s 8K TV was that it received an abnormal error when it received a signal containing Jitter. The Debug GUI of Allion AJSC-1 can quickly find the source of the error.

In addition, Link Training’s communication is also another issue. Through another DDC Monitor GUI, you can quickly find out if the relevant Register is compliant with the HDMI 2.1 specification.

There are still many unknown and potential risks in 8K technology. As one of the leading brands in the industry, Allion has taken the lead in the cooperation of testing instruments and equipment and professional testing technology. For more details on 8K TV, please contact us!