A retrospective
8K TV production is gradually on track
Compared with the unsatisfactory production of 8K movies, 8K TV production is gradually on the right track. As early as more than two years ago, we already had our own CCTV-8K UHD CCTV 8K ultra-high-definition channel, and this is also the second 8K ultra-high-definition TV broadcasting channel in the world. The world's first 8K TV broadcast channel is the NHK BS8K ultra-high-definition channel launched by Japan's NHK TV station. Interestingly, both the CCTV-8K ultra-high-definition channel and NHK BS8K were set up to broadcast the Olympic Games with a higher standard of picture standards, the former is the Winter Olympics in Beijing, China, and the latter is the Summer Olympics in Tokyo, Japan. In addition to the importance that Asian countries attach to the broadcast of the Olympic Games and people's enthusiasm for watching the event, it can also reflect the high requirements of sports events for picture quality, especially in terms of picture resolution.
Although both CCTV-8K channel and NHK BS8K channel can achieve 8K UHD picture resolution, specifically 7860×4320, but from the perspective of technical specifications, there are still certain differences between these two 8K TV broadcast channels from China and Japan. First of all, in terms of broadcasting methods, CCTV-8K channel adopts the cable TV method that we are familiar with, and it needs to broadcast 8K TV programs through 8K set-top boxes. NHK BS8K channel is a relatively old-fashioned satellite TV broadcasting method, using BS satellite channel 14 at 110° east longitude in Japan, which requires special satellite TV receiving equipment to watch. The second point is the difference in video coding formats. According to Chapter VIII "Technical Requirements for the Coding and Compression of 8K UHD TV Broadcast Signals of China Central Radio and Television Station (Provisional)" promulgated in January 2021, CCTV-8K channel adopts the domestic AVS3 video coding format, and the video coding bit rate is not less than 120Mbps. This also means that if you want to play CCTV-8K channels smoothly, you must use a playback device that supports AVS3 decoding.
In addition, in Chapter 9 "8K UHD TV INTERACTIVE ON-DEMAND technical requirements", it is pointed out that the 8K UHD TV interactive on-demand file format parameters, of which the total bit rate needs to be greater than 80Mbps, and the encoding requirements are relaxed to AVS3, H.266 and H.265, so that more 8K interactive set-top boxes can be compatible. It needs to be added here that AVS3 is the third-generation coding technology standard formulated by the AVS digital audio and video coding technology standard working group in China, which specifically adds AI technology, focusing on intelligent coding, and the coding efficiency is increased by 20% even compared with the next generation of HEVC H.266/VCC, with ultra-high compression efficiency, mainly for 8K ultra-high-definition and 5G media applications.
On January 24, 2022, the CCTV-8K ultra-high-definition channel was officially launched, and the "100 cities and 1000 screens" public large screen project was launched at the same time
On December 1, 2018, the NHK BS8K ultra-high-definition channel was officially launched
This is a schematic diagram of the development trend of video coding technology over the years, and AVS 3, AV1 and H.266 VCC are the three main technology-leading coding technologies
Relatively speaking, NHK has made many attempts in 8K video encoding technology format, as early as IBC 2008 in the test of 8K real-time transmission and playback of satellite and IP networks, using MPEG2 encoding format, with a bit rate of up to 650Mbit/s, and later with the BBC for the 8K live broadcast of the London Olympics, it is using H.264 encoding format, and the bit rate has dropped to 280Mbit/s, until today's NHK The BS8K channel uses HEVC encoding format, and the bitrate is 100Mbit/s, which is 800Mbps. It can be seen that because the AVS3 video coding technology used in CCTV-8K channel has higher compression efficiency and lower requirements for transmission bandwidth, it can realize a wider coverage of cable TV on demand.
Third, in terms of audio coding, the CCTV-8K channel is also different from the NHK BS8K channel, the former uses 5.1 surround sound coding, and the latter can reach up to an astonishing 22.2 channels. According to the current configuration of the living room TV audio system, the ordinary family system with a 5.1-channel surround sound audio system is still a minority. Therefore, from this point of view, the CCTV-8K channel uses 5.1 surround sound coding, rather than a larger-scale immersive audio coding technology, which is quite sufficient for the domestic market.
Comparison of the main technical formats of China's CCTV-8K ultra-high-definition channel and Japan's NHK BS8K ultra-high-definition channel
Explore the possibilities of 8K real-time network streaming program production, transmission and playback
In addition to the launch of 8K TV and radio channels in China and Japan, Europe and the United States have also carried out a lot of research and practice on the production, transmission and playback of 8K online streaming media video in recent years. One of the most notable was a pilot of 8K live network streaming across Asia, Europe, North America and South America in December 2020. Indeed, if 8K program sources mainly use online streaming video services to cover the global market in the future, the global trial of 8K to achieve online streaming media broadcast is an indispensable and important link. The 8K real-time network streaming program broadcast test is mainly divided into four parts, namely 8K program live real-time recording, HEVC real-time encoding, ultra-low latency real-time Internet transmission, and 8K HEVC decoding and playback. The live real-time recording of 8K programs was handled by PSNC 8K Production Lab in Poland, and the 8K video encoding and transmission part was completed by Spin Digital, which was finally broadcast in real time at NHK's headquarters in Tokyo, Japan, Globo headquarters in Rio de Janeiro, Brazil, Intel Portland, USA, and Spin Digital in Berlin, Germany. The program consists of a music recital.
In December 2020, 8K TV programs recorded live by PSNC 8K Production Lab in Poland were streamed over the Internet to Tokyo, Japan, Rio de Janeiro, Brazil, and Portland, USA through Spin Digital's HEVC video coding technology
Shoot in real-time with 8K cameras in PSNC's 8K TV production lab
PSNC's control room for real-time production of 8K video and 5.1-channel audio
In terms of related technical parameters, 3 Sony F65 CineAlta cameras are used for 8K live recording, and the video format of 8K output is 7680x4320/59.94Hz/4:2:0/10bit/SDR/BT.709. Nowadays, it seems that the higher specification HDR video format was not used at that time, which is indeed a bit regrettable. In terms of video coding system, due to the cost of equipment, H.266 and AV1 with higher compression ratio were not used in this experiment, but continued to use HEVC, and the encoder used the Spin Enc Live v1.0 encoder from Spin Digital, and the bitrate stream reached 120Mbit/s in low latency mode, which is close to 960Mbps bandwidth. In terms of audio, AAC-LC encoding is used, and the bitrate is 384kbit/s 5.1-channel surround sound. In terms of playback, it uses Spin Digital Media Player, and two PC systems equipped with HDMI 2.1 and 12G SDI interfaces, and the display equipment is a Sony KD-75ZH8 TV. The final test results were quite successful, which also laid a solid foundation for future 8K network video streaming services.
8K real-time live streaming workflow
System frame diagram of the Spin Enc real-time 8K encoder
The interface mode of 8K display device includes a single HDMI 2.1 port, 4 HDMI 2.0 ports, and 4 SDI to HDMI 2.1 ports
Analysis of the development of SoC system chips for 8K playback equipment
From the progress of the 8K program source mentioned above, it can be seen that in addition to the 8K movie, the rest of the 8K TV program recording and broadcasting, 8K network streaming services are gradually on the right track, I believe that the near future will really usher in the popularization of the program source8K. Next, we will talk about the 8K player, which is a very core component of the 8K audio and video system. From the current trend, 8K players mainly take the way of network and hard disk local playback function. Of course, we will not rule out the possibility of the emergence of 8K disc players, whether it is Blu-ray 8K, fluorescent 8K, or 8K disc players with other technologies, but for the time being, it seems that no matter whether the major film companies have little intention of launching 8K discs, they are more inclined to 8K network streaming services.
How to find a high-performance 8K player is a big problem for many gamers. The core key to determining the playback performance of the 8K player lies in the overall performance of the SoC system chip used inside, the most direct impact is the compatibility of video hardware decoding, for example, the early launch8K SoC does not support AV1 hardware decoding, and can only be software through the CPU, which leads to a series of problems such as playback flashback, unsmooth playback stuttering, loss of detail in the playback frame drop, asynchronous sound and picture, and serious player heating. In 2024, this problem has been significantly improved, and major chip manufacturers have made a lot of efforts to decode 8K video hardware, and the 8K video coding formats that can be supported are becoming more and more abundant.
At present, the mainstream 8K playback SoC system-on-chip solutions include:
●联发科MediaTek Pentonic 2000与S900
●Amlogic S928X series
●Rockchip RK3588 series
●国科微Goke GK6525
●海思Hisilicon Hi3796CV900与Hi3751V900
It should be noted that some of the above SoC SoCs that can support 8K playback functions are not mainly aimed at the player or set-top box market, but are used in 8K TVs or smart home systems. Of course, with the hardware technical support and software support of the player manufacturer, it is entirely possible to apply the relevant SoC system to the 8K player.
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To be continued