Abstract: Since a large screen manufacturer launched a networked distributed image splicing control system about three years ago, many similar distributed image controllers have appeared in the large screen market in the past two years. This article mainly introduces the different technical features and comparisons of Delta's DVCS distributed image control system with other controllers.
The so-called networked distributed image control system uses an IP network as the signal transmission channel and employs real-time image processing technology to compress and encode various video signal sources (including RGB signals, video signals, high-definition video, audio signals, etc.), package the data into IP bitstreams that can be transmitted over Ethernet, and the display end receives various signal bitstreams and decodes and restores them into images for display in real time.
Distributed image controller systems can be applied to DLP and LCD splicing display systems in various industries to achieve massive high-performance signal access processing and large-scale signal display, including railway command and dispatch, public security, security, coal, petrochemical, power, communications, transportation and other industries.
I. Composition of a Networked Distributed Image Control System
A networked distributed image controller system typically consists of the following components:
(1) Signal input module: It can encode various video signal sources (including RGB signal, video signal, high-definition signal, audio signal, etc.) into IP bitstreams that can be transmitted over Ethernet in real time;
(2) Display output module: capable of receiving various different signal source IP streams and decoding and displaying them in real time;
(3) Ethernet switch: forwards the IP code stream of the signal to the display processor according to the IP address;
(4) Control and management software: Users can control and set each processor through the control and management software, and display various signals in real time.
II. Functional Requirements of Networked Distributed Image Control System
As the core device for signal processing and display in DLP and LCD large-screen splicing display systems, the distributed image controller system must have at least the following signal input, processing, and display functions to meet the application needs in various industries:
(1) Computer RGB/DVI signal: Usually, it is necessary to connect and process several to dozens of RGB/DVI signals for display, and the resolution should support the mainstream 1024×768～1920×1200.
(2) Analog video signals: It is usually necessary to access and process dozens or even hundreds of analog video signals, such as signals from CCTV surveillance video matrix, signals from other cameras, etc.
(3) High-definition video signals: Usually, it is necessary to access and process several to dozens of high-definition video signals, such as signals from video conferencing systems, DVDs, high-definition cameras, etc., and should support mainstream 1080i and 1080p high-definition.
(4) IP Digital Video Signals: In an increasing number of industry applications, large-screen systems are required to directly access and process IP camera signals from the network without the need for third-party video decoding equipment. They should support mainstream encoding formats such as H.264, MJPEG, and MPEG-2/4, and support CIF, 4CIF(D1), 720p, and 1080p resolution decoding and display.
(5) Ultra-high resolution image signals: In some special industry applications, large screen systems are required to access and process display ultra-high resolution dynamic images, such as geographic information GIS, satellite positioning GPS, power monitoring SCADA, train dispatching signals SIG, etc., and should be able to fully display ultra-high resolution images with a resolution of at least M rows × N columns spliced together.
(6) Audio signals: In some command and control room applications, the large screen system is required to be able to access and process the synchronous playback of video and audio signals to better meet the needs of command and dispatch and emergency command.
The signals mentioned above are basically the main signal sources involved in current large-screen display industry applications. Only controllers that can meet the above signal access requirements can be considered qualified distributed image controllers that meet application needs. Some controllers that can only access the simplest RGB and video signals have a very limited scope of use and cannot be considered true distributed image controller systems in a strict sense.
III. Performance Requirements of Networked Distributed Image Control Systems
A truly networked distributed image controller system should possess the following performance characteristics:
(1) Network distributed architecture: The true meaning of networked distributed image processing lies in the end-to-end independent channels. Whether it is the front-end signal input module or the back-end display output module, they should be independent devices. Each signal input device corresponds to only one signal source, and each display output device corresponds to only one display unit. Only in this way can the real-time processing and display of each signal be guaranteed.
(2) Networked image transmission: All video signal sources, including RGB signals, video signals, high-definition video signals, audio signals, etc., are encoded into a unified bitstream format and transmitted on Ethernet. All image bitstreams are flexibly connected to the display output module through Ethernet switches.
(3) High-performance image processing: High-performance DSP and FPGA are used as the image processing platform to realize real-time image processing and display. The embedded computing platform has the advantages of high performance, high reliability and low power consumption, which is truly suitable for the high requirements of security and reliability of large-screen monitoring systems.
(4) Adopting independent encoding algorithm: Adopting an independent dedicated encoding format designed specifically for splicing display system to achieve full compatibility with various video signals and ultra-low latency image display, and to achieve accurate synchronous splicing display.
(5) Real-time display of all signals: All signal windows can be of any size, position, and superimposed. Multiple real-time video/RGB signals can be processed and displayed simultaneously on a single screen. The more signals that can be displayed at the same time, the more powerful the product's performance.
(6) High performance and high reliability: The failure of a certain input/output device does not affect the normal operation of the signal display and control system of other devices. All input/output devices support quick replacement on site. The system can automatically identify the new processor device and put it into operation, so as to minimize the fault maintenance time.
(7) The management software has complete functions: it supports the management of multiple signal sources, supports real-time preview of multiple signals and real-time display of all windows on the large screen, supports signal source multicast, realizes synchronous real-time playback on multiple video walls, supports multi-level permission management, and supports multi-user operation control, etc.
Distributed controller systems from different manufacturers vary significantly in performance, including signal input, processing, and display capabilities, due to differences in the technologies and bitstream formats they employ. Some manufacturers use JPEG or H.264 codecs to create controllers that are not true distributed image controller systems in essence, but rather networked signal transmission and display products.
IV. Comparison of Delta DVCS Distributed Image Control System with Other Distributed Controller Technologies
A technical comparison between Delta's DVCS distributed image control system and other distributed controllers:
