The development of a new broadcast-grade 8K EFP camera and its application at the international winter games
Mr. SHI Liang, Mrs. DING Xueling, Mr. ZHOU Yi
(1. Academy of Broadcasting Science, NRTA, Beijing 100086, China; 2. China Media Group, Beijing 100045, China; 3. China Association of Press of Technicians, Beijing 100037, China)
Abstract: This paper introduces the technical framework and design scheme of the newly developed 8K ultra-high-definition camera system, and focuses on the analysis of its core technical advantages, as well as identifying 10 technical highlights and six technical indicators achieved. It also analyzes the system’s practical application at the international winter games. The new broadcast-grade 8K EFP camera fills the gap of domestic 8K image vision and camera products in the field of broadcast, film and television, which is conducive to improving the current situation of backward front-end equipment for video recording and editing in our country, and is expected to promote the development of the entire ultra-high-definition video industry chain.
Keywords: 8K EFP, studio camera, Ultra HD video production and broadcast, international winter games
Ⅰ. Status and Problems of 8K UHD Camera Market
1.1 8K UHD and its industry chain
Ultra-High Definition (UHD) video is a new intergenerational evolution of video technology following analog, standard definition and high definition, paralleling 5G and artificial intelligence as an important development direction of the latest generation of information technology. 8K UHD has a resolution of 7680×4320 pixels, with the number of pixels in a single frame 16 times higher than high definition, and with 4320 lines, gives a theoretical horizontal clarity four times higher than high definition. 8K UHD video significantly improves video quality and sound effects in all respects, providing viewers with an immersive viewing experience. More intuitively, the video is presented more clearly on display screen of the same size as an equivalent 4KUHD video screen, with better image quality and richer visual details.
The overall industry chain of UHD video can be divided into four levels: core components, equipment layer, service layer, and application layer. The core components mainly include photosensitive devices, storage chips, codec chips, image chips, processor chips, and display panels. The equipment layer includes video production and broadcasting equipment, network transmission equipment, and terminal presentation equipment. The service layer includes content services, integration services, and distribution services, etc. The application layer includes fields such as broadcasting and television, education and entertainment, security monitoring, medical and health care, etc. UHD cameras belong to the forefront of the equipment layer and are also the most important video production and broadcasting equipment.
1.2 Characteristics and Capabilities of 8K Camera Systems
The 8K camera is the starting point of the UHD video industry, the capability of which directly determines the quality of the source video of the 8K UHD video chain. Currently, 8K cameras are mainly divided into professional broadcast grade and non-broadcast grade cameras. 8K professional broadcast-grade cameras require extremely powerful hardware processing capabilities, as well as high heat dissipation requirements during data processing, large photoreceptor elements, etc. Simultaneously, 8K cameras need to provide good support for high dynamic range, wide color gamut, etc., to maximize the quality of recording and reproduction of the scene. For in-camera recording, it is necessary to provide richer and more effective information for post-production and storage. The bit rate of recorded video files can reach several gigabytes, requiring extremely high I/O performance for real-time recording. The importance of broadcast-grade production scenes is important, as they require high stability and reliability of equipment and related systems, which are difficult for non-professional broadcast-grade equipment to reach (CCID, 2021).
Ⅱ. Technology architecture and design scheme of the 8K UHD camera system
The 8K UHD camera system is the pinnacle of technology in the global camera manufacturing industry, integrating cutting-edge technologies such as semiconductor photosensitive technology, integrated electronic circuit technology, precision machining technology, large-scale software system control, intelligent control and optical transmission technology. An 8K UHD camera system consists of nearly 200,000 components; the difficulty of innovation is self-evident.
2.1 Technical architecture
A domestic 8K broadcast-grade camera mainly consists of an optical lens, photoelectric conversion system, image signal processing (ISP) unit, input and output units and accessories. Among them, the photoelectric conversion system and ISP unit are the critical components of the camera, as shown in the following figure:
Fig. 1 Technical architecture of the 8K UHD camera
(1) Customized 8K CMOS chip for photoelectric conversion. The chip has a resolution of over 65 million pixels, with low readout noise, high dynamic range, excellent shutter efficiency and angular response. Compared to a traditional CCD chip, CMOS also has the characteristics of fast imaging speed, simple device structure, small size, low power consumption, high cost-effectiveness and easy control.
(2) The image signal processing unit is independently developed based on deep research. The ISP of a broadcast-grade camera involves dozens of TV standards. Without long-term experience in broadcasting technology, it is difficult to achieve complete coverage of all standards. The newly produced 8K UHD system is based on the in-depth understanding of professional user requirements and usage habits in the broadcasting and television industry, and is fully independently developed software.
(3) Other main technical links: ①Serial-parallel conversion, which converts the scanned serial signal into a parallel signal that can be recognized by the computer. They also reduce the processing pressure on the IC chip caused by instantaneous large amounts of data, ultra-high speed processing, and transmission; ②Shaping, adding signal indexes and numbering information (such as ID, signal source, signal attributes, etc.), converts numerical values into addresses for subsequent image signal processing; ③Serial digital interface for long-distance transmission of image signals and audio and video signals (Zhou Yi, 2020).
2.2 Design scheme
A broadcast-grade 8K EFP camera mainly consists of a photosensitive and photoelectric conversion system, signal and image processing system, signal packaging transmission and uncompressed photoelectric transmission system, and CCU station (decoding, processing, signal output interface system).
(1) Photosensitive and photoelectric conversion system
The 8K camera has a customized CMOS photoreceptor chip with microprism design. Industry experience shows that prismatic multi-chip sensors will have better image quality. Therefore, the 8K camera sensor adopts micro-prism spectroscopy technology, which takes into account the high resolution and high quality of the image, improving the accuracy of image spectroscopy and color reproduction. This technology that improves image color restoration without using rendering is a characteristic of this camera.
(2) Signal and image processing system
Camera image processing is the most important part of the whole system. The biggest feature of the 8K camera system is the use of a four real-time parallel processing calculation scheme. In this section, the processing of high dynamics, color gamut, color matrix, wavelength division, etc. of the camera is completed.
(3) Signal packing transmission and uncompressed optoelectronic transmission system
In this system, the self-developed micro dense wavelength division multiplexing (WDM) technology is utilized to achieve 8K lossless and uncompressed signal transmission.
(4) CCU: decoding, processing and signal output interface system
As the main signal port of the system, the CCU completes the functions of decoding, optoelectronic conversion and signal recovery of each signal in this section, which is one of the most important parts of the whole EFP system. The following figure shows the front and rear CCU panel design. :
Fig. 2 CCU design diagram
Ⅲ. Technical advantages, characteristics and performance indicators
3.1 Core technological advantages
(1) Advantages of image acquisition technology
Earlier 8K camera systems used prism technology, which requires three monochrome CMOS chips to recognize red, green and blue light respectively. Then, the three monochrome lights are combined to achieve an 8K-level of 90 million pixels. Enlargement of the image may result in blurred edges, so the shooting effect in dark environments is very unsatisfactory. Due to the fact that all three filters must be aligned to the same point, repeated calibration is required. It requires extremely high mechanical processing technology, thus resulting in slow production speed and high cost of the camera.
The newly produced 8K camera system adopts point-of-view (POV) technology, which is an innovation based on a Bayer color filter array to meet the higher color acquisition needs of the broadcasting and television industry. Unlike a Bayer filter array which scans pixels and calculates pixel values through interpolation, POV stores and restores all color information to minimize chromaticity loss. The images captured by the 8K cameras have higher resolution, brighter and richer colors, less noise, and no distortion or blurred edges. Moreover, the shooting effect in dark environments far exceeds that of other 8K cameras.
(2) Advantages of image signal processing
Image signal processing is used to process the output data of image sensors, including over 70 functions such as automatic white balance, color correction, gamma correction, noise removal, color space conversion, edge enhancement, color and contrast enhancement. The hardware part of image signal processing mainly consists of DSP+FPGA, implemented through a large amount of software. 160 mapping tables are used in the calculation process to ensure efficiency. The core algorithm based on the logic and mapping relationship of series mapping tables is a key technical barrier that has been overcome.
3.2 Ten Technical Highlights
(1) The first camera integration structure with internal modular design (including a full set of IC of FPGA)
The advantage of modular design lies in its flexibility, which is the trend of future development. The biggest advantage of modular design is that the plug-in modules can be quickly disassembled and assembled. And they can be replaced according to customer needs, making maintenance more convenient and power consumption easier to control. Modularity will become a prerequisite for future lightweight/miniaturized cameras.
(2) Three self-developed real-time image processing and color processing IP cores
Three IP cores solve the problem of combining core software and hardware. All the color IP cores are self-developed. One of the three IP cores is JP2000, one is dedicated to data integration and specification, and the other is ISP (Image Signal Processing). ISP processing mainly includes white balance, gamma processing, spiking, PQ processing, color broadening and color processing, etc. Such advanced Image Processing is at the heart of the success of the 8K camera system and one of the key achievements in delivering it.. Each manufacturer has its own unique algorithms, which is one of the important barriers for international giants to stay ahead of the game.
(3) Self-developed full set of AI image processing system software
AI image processing systems can significantly enhance the user experience. For example, by learning the usage habits of photographers, they can automatically make judgments and adjustments to the commonly used functions of the keypad, making it convenient for photographers. Meanwhile, the habits of different photographers and users will be intelligently stored in specific user areas. The functions that users use more will be summarized and refined at the bottom level, and presented on the keypad to enhance the user experience.
(4) The first CCU lossless transmission equipment based on a dense wave division system
The CCU (camera control unit) is used to control the images captured by the camera head and transmit them to the next stage for live broadcast. The linear power supply of the CCU achieves a stray wave and ripple of less than 1 millivolt. It ensures that the CCU equipment will not be interrupted or disconnected during live broadcasting when the instantaneous current of the linear power supply is very high, thus improving the high reliability of the CCU.
(5) Development of ultra-compact dense-wave combiners and splitters (up to 64 channels)
The ultra-compact dense wave combiner and splitter solve the transmission problem when large capacity, high speed and multiple services are transmitted simultaneously. The dense wave splitter system can achieve a maximum of 64 parallel channels, allowing the camera to process more data within a limited bandwidth. And the size of the combiner and splitter is only about 50mm.
(6) Innovative production of a transmission system based on dense wavelength division
The advantage of a dense wavelength division multiplexing (WDM) system is that it is a method of transmitting multiple wavelengths of optical signals that carry different information by multiplexing them into a single optical fiber. Compared to traditional WDM, the adjacent wavelengths are more narrowly spaced. Therefore, it can realize ultra-large capacity, ultra-long-distance transmission, transparent transmission of data and save optical fiber resources. The dense WDM allows for more data to be processed on a limited bandwidth.
(7) New on-board camera control panel (including remote control unit OCP)
The new 8K camera adopts ink screen with lower power consumption as the display screen. Ink screen is one of the display products with low power consumption, excellent performance and high reliability. Even if there is an operational error or power failure, the information on the screen still exists. At present, the software and display inside the ink screen are all self-developed, capable of local refresh, with a refresh speed of over 0.3 seconds/time. Combined with the intelligent definition and recommendation of the user interface, it can improve the user experience and smoothness of operation.
(8) The first adapter ring that can be adapted to various camera lens mounts
Advantages of self-designed lens mount: ①Good stability. The screws used in broadcast-grade cameras prevent micron-level shaking, otherwise the flange distance of the camera will change, resulting in blurred images. Therefore, there are strict requirements for the design of the adapter. Our 8K broadcast-grade camera lens mount, customized by the manufacturer in Shanghai, is designed independently, and micron-level shaking does not occur; ②Wide adaptability range and versatile application scenarios. Our 8K broadcast-grade camera lens mount supports EF mount, PL mount and B4 mount, etc.
(9) Design and manufacture of aviation aluminum housings and broadcast-grade dedicated EFP and ENG housings
The 8K EFP camera currently uses an aviation aluminum housing – the first one in China to use aviation aluminum – in line with the trend of future development of EFP camera housings.
(10) Development of high-power, ultra-low noise linear power supply system
Compared with other brands of switching power supply, the developed linear power supply system has the advantages of less electromagnetic interference, low ripple coefficient; higher voltage regulation rate, strong transient current follow-up ability; simple design, low maintenance cost, and good lightning strike resistance.
3.3 Realization of the six major performance indicators
(1) High definition: 7680 × 4320, 8192 × 4320 (for film projector)
(2) High frame rate: 50p, 60p, 59.94p
(3) High Dynamic: SDR: 11; HDR: HLG- 1000/PQ
(4) Wide Color Gamut: BT.2020 & REC.709
(5) High signal-to-noise ratio: over 65dB
(6) Gain: analog/digital dual gain (to solve the different gain characteristics of the bright and dark field)
Ⅳ. Applications of the broadcast-grade 8K EFP cameras at international winter games
After many rounds of tests, the State Key Laboratory of China Media Group (CMG) has identified the UDCAM-9000 8K EFP camera as the only domestic product whose four key technical indicators (high definition, high frame rate, high dynamic range, wide color gamut) all meet the 8K technical specifications of CMG. In February 2022, the broadcast-grade 8K EFP camera was formally applied to the international winter games after subjective evaluation and objective testing by the State Key Laboratory of UHD Audiovisual in CMG.
The “Ice Ribbon” is the competition venue for speed skating. The system operated for 15 days from February 5th to 19th, broadcasting all the events of Avenue Speed Skating. A total of six 8K EFP cameras were used in the 8K public signal production site for speed skating, among which the No.5 and No.6 cameras used the 8K UHD broadcast-grade EFP cameras. The 8K cameras and imported 8K cameras were used together for the program production at the competition venue, which perfectly accomplished the 8K live broadcasting task and presented detailed and beautiful images . The international winter games was the first to use 8K technology to broadcast the opening ceremony live in its history. It was also the first 8K EFP camera system that was independently developed and produced by a Chinese enterprise in the 8K UHD broadcasting system.
Ⅴ. Conclusion
Certain breakthroughs have been made in the research and industrialization of 8K key technology products. A series of major events have driven the explosive growth of 8K UHD camera system and recording and editing equipment. For example, the “Spring Festival Gala in 2021 and 2022” of CMG has fully experimented with 8K recording and live broadcasting (cinema line broadcasting), Qatar Football World Cup in 2022, etc. With the support of 5G networks and AI, 8K will cover more areas of consumers’ work and life. As an important branch of high-end manufacturing in China, the newly developed 8K EFP camera system has filled the gap in the current 8K image vision, broadcasting film and television camera products in China. Through research and development, we have mastered a batch of technical patents for 8K UHD cameras and shooting equipment. The next step is to promote the marketization and industrialization of the products. By effectively promoting and driving the production of optical lenses, optical precision processing, CMOS chips, lens mount design and production, high-end monitors, precision industrial design and processing, related software development and a series of high-end industry, it helps drive the upgrading and modernization of China’s creative industries.
