TV conference system based on MPEG technology

TV conference system based on MPEG technology

Mountain song

MPEG technology ---- MPEG technology is the crystallization of international image compression coding technology in the past 10 years, and is also a popular technology that emerges in the information age. With the emergence and application of various image compression methods, the International Standardization Organization (ISO) and ITS (ITU) is committed to formulating unified norms and standards, and has launched a TV conference H.261 suggestion, still image compression JPEG Standard, black and white binary image compressed JBIG standard, motor image compression MPEG-1, MPEG-2 standard. These standards and recommendations have greatly facilitated image compression coding. ---- ISO's Activity Image Expert Group proposed a draft recommendation for the digital storage medium and its audio of 1.5Mbps, as the ISO / IEC11172 standard, adopted in 1992, is used to MPEG-1 standard. MPEG-1 uses SIF format, the frame rate is 25 ~ 30 frames / sec, the code rate is 1.5Mbps (where the video is about 1.2Mbps, the audio is about 0.3Mbps), the image quality is better than the household VHS recorder, audio (double channel) close CD quality. MPEG-1 can not only be used in digital storage media, but also available for image communication and digital video broadcasting, and high-quality conference television systems, which compressed data can be transmitted, managed, and receipt in the form of files. The MPEG-1 standard specifies the format of the binary bitstream encoding output and decoding input. MPEG-2 is followed by MPEG-1, MPEG is fully compatible with another video compression standard. The basic algorithm of the MPEG-2 standard is also a predicted prediction of motion compensation and an inter-DCT inter-interpolated code, which is input signal being a typical CCIR601 or a comparable digital video signal. It and the main difference of MPEG-1 lies in the processing of interlaced video, and MPEG-2 can effectively support the TV's interlaced scan. In addition, the MPEG-2 standard also provides image grade selection encoding mode, which is very useful for image services that provide multiple clarity. Therefore, MPEG-2 can be applied to a broader application area, mainly including digital storage media, broadcast television, and communication. ---- Conference TV In the early days of development, the H.261 video codec is usually used due to limit line bandwidth. However, with the development of video transmission technology, especially the rapid development of fiber optic lines and the improvement of the requirements of image quality, there has been a conference television system with MPEG codec, which provides super-VCD quality. And broadcast level images and sounds. MPEG conference TV network can also carry out video services such as CATV, VOD, digital TV to avoid duplication of construction, in line with the development trend of the third network. It can not only be transmitted in the post and telecommunication public network, but also transmit in various networks including LAN, WAN, CATV and other networks, which will be used to achieve three-network combination. In particular, conference TVs with MPEG solutions in satellite communication systems have a unique advantage, and their image and sound quality are good. When the channel is accidentally faulty, the MPEG system can establish a new synchronization mechanism within less than 1 second to quickly resume normal conference TV. It is foreseeable that a conference TV with MPEG technology will be widely used in all countries around the world and have achieved good social and economic benefits. Application examples on satellite ---- 1. System structure ---- The system structure is shown in Figure 1. ---- 2. Main function of the main control venue equipment and multi-point control computer ---- system Features: ---- · Unified User Management System: Added the control satellite network based on the original MCU control software The module makes the satellite backbone network and the provincial secondary network, the three-level network of the city and the four-level network of the district and county form a unified whole. ---- · Intuitive network schematic: After running the system software, the network diagram of the system appears, and simultaneously distinguishes the transmission and reception status of each sub-conference point (where red is used in red).

---- · Flexible parameter setting: After selecting a snap-in-point point, there is a parameter status of its UMOD. At this time, if you need to view the image of this point, you can set the data rate and the send state of its transmission and click Option. After the software is processed, a series of control commands will be sent to the satellite network management device to set this UMOD after a serial port of the PC after processing. ---- · Multi-level MCU connection method: Since the control signal can be easily passed to any provincial sub-conference point, the Chair control point can not only control the camera and the action of the PTZ, but also The secondary MCU control ground can be added at the sub-meeting point, and the local conference television system of the municipal level. Increase the third-level MCU in the third stage to extend the system to the county level. At this point, the system supports the image remote control switching of the whole network. ---- 3. Splitting equipment and instructions ---- Most of the split venues are usually in a single state, and when you need to make a statement, you can press the application to speak. This signal is given to the center queuing machine After the software is handled, the transmit and receive status of the various conference points of the system is changed through the M & C control port of the PC through the serial port of the PC. ---- 4. System function and system characteristics ---- (1) System function ---- a. Video function ---- Using the switching method to bring the local venue screen, the video signal of the local video source and The video data on the recorder is transmitted to the distant venue; --- · You can record the image of the local or remote venue as needed; --- · Frame frequency is adjustable between 15 and 30 frames / second to achieve the picture Best results; --- · In the process of TV conference, you can play subtitles in real time on the screen. ---- b. Audio function ---- · You can transfer all the way stereo; ---- · The image and sound can be fully synchronized; - · · · · Distance. ---- C. Control Function ---- · Chair control: PC issued a polling control command to M & C simulation port loop control each UMOD's transmission and receiving work, so that the main venue can poll the image of any venue An image of any meeting point can be called directly, specifying it as a broadcast image. ---- · Some venue can be made to make a statement: Each single-collection venue can transmit signals to the control center of the control center, and then control the local venue by M & C simulation port and Overhead by M & C simulation port and overhead. UMOD's working status. ---- · Single-haired branch venue can be used in turn: can be implemented using the system's polling function. ---- (2) System characteristics ---- a. Fast real-time ---- can promptly hold a TV conference at any time, quickly transfer the venue image, or any part venue image to the country. According to the specific requirements, the image can also be connected to the office. ---- b. Upgraded expansion ---- Upgrade the system to the MPEG-2 system in the case of the transmission bandwidth, in the case of poor transmission bandwidth. ---- C. Technology Advancement ---- Whether it is a VOD system or a future digital cable TV system uses MPEG file format. In addition, Web TV and IP TV are also MPEG-based file format. Therefore, the conference television system consisting of MPEG-1 can meet the development needs of today's technology, open and expandability, easy to achieve data preservation and retrieval. ---- D. Economic ---- The current international TV conference system is very expensive, but some manufacturers in China have also formed a performance price than a very good product, and in the public security, the army system is good. Applications. ---- E. Practical principles ---- With the premise of ensuring the use requirements and technical feasibility, it has easy operation, management, and practical excellence, and can modify and expand system device functions according to the actual needs of the user. . --- f. Standards and Standards ---- The main equipment and communication software and agreements are in line with relevant standards and technical specifications at home and abroad. (ISO / IEC, ITUT, CCIR601, MPEG1, MPEG2, E1, V.35, G.703, etc.). Computer World Daily 2000/07/24