What should be done about the production scheme and construction process of live broadcast of the annual meeting?

In recent years, the company has made bold attempts in new media live broadcast, and accumulated rich practical experience in multi-venue media live broadcast in different places. Taking the technical scheme of an important event as an example, this paper expounds the design and implementation method of this live broadcast technology. The application of this technology can expand the influence of the event and create the linkage between the main venue and the sub-venue.

In order to expand the influence and create a warm atmosphere, the organizer asked the TV station to display the activities of various venues on the big screen and broadcast them live interactively. The effect is that the main venue can watch and listen to the video and audio signals of other sub-venues, and the sub-venues can also listen to and watch the video and audio signals of the main venue. After investigation and communication with operators and relevant departments in the early stage, system debugging and network construction testing by technicians in the later stage, two schemes were initially selected.

One solution is to push and pull live broadcasts on the Internet. Technically, it is necessary to arrange shooting locations and network dedicated lines in each venue, output the total video and audio signals of the scene through switching equipment for encoding, and then output the code stream to the cloud server in a push way. The release and scheduling of signal images are completed by the cloud software management interface. This scheme has the advantages of fast technology deployment, simple structure and quick realization in a short time, and it is the main method for media companies to realize multi-venue live broadcast at present. In addition, the equipment is relatively simple, and the background is managed by the live broadcast platform, so the cost is low. Most live broadcast platforms use this scheme for live broadcast, and the personnel and equipment are packaged and rented, so there are many activity cases. For example, a company has taken root in South China to provide services for TV broadcasting service providers in Greater Bay Area. The team contracted live broadcast projects of many important domestic events and programs. The company has long-term cooperative relations with Beijing Xingtuo Vision Culture Media Co., Ltd., Case Garden Network Technology (Guangzhou) Co., Ltd., Beijing Longju Culture Media Co., Ltd., Henan Satellite TV, Aoya Satellite TV and other enterprises and institutions. He has produced live programs broadcast by ESPN, a foreign copyright agency, with strong production strength. The live broadcast cases include: 20 19 Sanda World Finals (Guigang, Guangxi), EFP- Evergrande U 15/U 17 Football Championship (double production area), Henan Satellite TV-Wulin Wind Hengqin Peak Live, Glory Glory Boxing, WCBA- China Women's Basketball League. The disadvantage is that due to the low bit rate of live broadcast, the video quality is usually less than 6M, and the delay is also serious, usually 6 to 10 second.

Another scheme is live television. Audio and video on-site production systems have been installed in each venue. The broadcast-level field signals output by the three-camera broadcast-level camera and the field exchange station are converted into IP video streams through encoders, and then transmitted to the video-audio optical terminal for signal transmission. Two-way data interaction is completed through the operator's internal optical fiber network, STN private network or MSTP integrated service platform. The switching mode of remote video and TV live broadcast is usually divided into three levels. The first level switching is responsible for the generation of total signals, the second level switching is responsible for summarizing the signals of various venues for the first level switching, and the third level switching is responsible for the generation of live broadcast signals of various venues. The whole system involves the collaborative participation of various departments and personnel (city and county TV stations, communication operators, equipment manufacturers and network operators). Advantages of this scheme: high live broadcast rate, obvious advantages in video and audio quality and clarity, and good security. Disadvantages: long debugging time, more manpower and equipment, and high cost.

Because the TV live broadcast scheme involves a wide range of technologies and good results, this paper chooses this scheme as the focus.

A technical scheme of live broadcast

1. Preparation

In the live broadcast, the company needs multi-department division of labor and cooperation, * * * to jointly carry out system testing and network construction, and the effect presentation needs to meet the following requirements:

◆ Video signals of each venue are connected to the big screen display;

◆ Video signals of the main venue can be seen on the big screen of each venue;

◆ The large screen of the main venue can switch and display the video signal of the sub-venue according to the program flow.

Technically, the video signals of the main venue and the sub-venue are stunt-switched through the video switching platform, and the video signals and audio signals are output to the live encoder, which collects and encodes the video and audio signals and publishes them to the TV broadcast live broadcast or streaming media server for distributed live broadcast on each platform. Users can watch and listen through TV broadcast, or visit the main site through mobile client, and then they can receive the conference information and choose to watch the live video of the conference after authentication.

The preparatory work includes:

◆ Coordinate the layout construction of operators, and provide live broadcast private network and private Internet access;

◆ Coordinate operators to provide STN platform transmission, and complete distribution and collaborative debugging of venues;

◆ Installation and debugging of video shooting and switching output systems in various venues;

◆ Installation and debugging of encoding and decoding and optical transceiver equipment in the main venue and sub-venue;

◆ System debugging;

◆ The outsourcing publicity team carries out pre-publicity

Efficient team structure, the strategic core comes from the international 4A advertisement Leo Boehner; The core of the product comes from HSBC, a world-renowned enterprise; The core of technology comes from the old industry giant Microsoft technology; Located in Guangzhou, China's first tier cities, where domestic e-commerce and Internet giants gather, it is in close contact with the industry and grasps cutting-edge information and resources. As a partner of Yuexiu Group, provide the group with the design and production of bound and online versions of the annual social responsibility report; As an application content producer of China Ping An Life Insurance Company of China Insurance Company, it provides various games and interactive applications for China Ping An Life Insurance Company of China Insurance Company.

2. Detailed rules for webcasting process

Pre-preparation: according to the live broadcast demand put forward by customers, make accurate live broadcast time, formulate mature live broadcast plan, introduce lottery elements to attract users; In the early stage, the professional team made tweets and small programs to be preheated and distributed through multiple channels to ensure the live broadcast effect; The company's professional service team guides the anchor modeling and is responsible for the live broadcast of the anchor makeup; Live props are fully equipped, and both indoor and outdoor live broadcasts are available. Live broadcast equipment includes but is not limited to tripod, microphone, camera, SLR and lighting.

Live broadcast: arrive at the site 2 hours in advance, adjust the lighting, add anti-shake effect, ensure the best live broadcast quality, confirm the best shooting position, and technicians will check the equipment and network speed.

Live broadcast: make sure the network is smooth. If you use wifi for mobile phone live broadcast, the flight mode will be turned on. Pilots will pay close attention to the network situation and make all-round emergency plans. The live assistant pays attention to the live broadcast, pays attention to the questions raised by the audience and interacts in time. During the live broadcast, the lottery interaction is carried out, and the QR code is placed on the live broadcast, so that users can scan the code to enter the group lottery and send gifts. Scan the code into the group to ensure that the number of live viewers does not drop and keep the live broadcast hot.

After live broadcast: generate live video in time and feed back live data.

3. Selection of equipment

The whole system consists of: video and audio equipment in the main venue (broadcast live car, TV live car, new media live system, network live universal machine, multi-channel codec). The production equipment is specifically an 8-way (extended 16) 4K ultra-high-definition broadcast vehicle and a set of 12-way high-definition EFP large-scale live broadcast operation.

UHD- 1 in-vehicle configuration of relay vehicle. Car body (including the front): one side12m, and the other side 4m; Camera: Sony HDC4300x8 (Canon 4K lens in each focal length); Operator: Sony XVS6000 2ME 28 key direct cutting; Matrix: Ross Ultrix 64x64 (12g) backup, with network switching; Synchronization: Tektronix SPG700 series synchronous generators and switches; Screen segmentation: Ross UltrixScape；; Peripheral modules: Opengear series Ross and Cobalt 9904, etc. Converter: Sony hdrc4000 HDR converter X2; Call system: RTS ZEUSIII +KP32/KP 12 panel EVS:XT-VIA /XT4K (up to 4 LSM stations as required) Recording: AJA kipro ultra plus audio: Yamaha CL3 main station, Yamaha -DM 1000 standby station, Dante audio routing and cabinet. )。 At the same time, it is equipped with a complete set of targeted live broadcast equipment including condenser microphone, external sound card, beauty camera, monitor headphones, live broadcast computer (streaming media), fill light and bracket accessories.

The main venue is the key to the success of the live broadcast of the event, so when building the system, we not only consider the safety and stability of the equipment, but also focus on backing up the key parts; Audio-visual equipment at the sub-venue; Portable video switching station; Encoding and decoding equipment; Optical transceiver; Live broadcast collection and distribution equipment; Internal data system of optical network; Network service center (streaming media server, WEB server, database server); Terminal equipment of each venue; LED large-screen display system in venues.

4. Network implementation scheme

Because the signal transmission distance of ordinary optical transceiver is too long, it is necessary to add relay equipment to amplify the optical signal to send and receive it normally, so the security is affected by the unstable factors of routing nodes. Therefore, we abandon the method of long-distance optical transmission of video and audio baseband signals and adopt the core transmission technology of network operators' private network and backbone transmission network. This scheme adopts telecom STN (Intelligent Transport Network), which is an enhanced packet networking technology developed by combining IP RAN and PTN technologies. It is a comprehensive application network that can carry video, audio and data. The biggest advantage is that the bandwidth can be adjusted flexibly, and high reliability is the guarantee. Through network management, end-to-end management can be realized, and the performance index is good (throughput, delay and packet loss rate). Audio and video signals are compressed by encoding and decoding, and transmitted through TS over IP, which is used for professional radio and television signal transmission. TS packets are encapsulated into IP packets, which are configured through the IP input/output interface on the radio and television codec equipment, encoded and IP encoded at the sending end, and decoded at the receiving end. The total delay of the system is less than two seconds, which can better complete the real-time transmission of audio and video signals around the country, and the transmission quality is stable and reliable, more flexible and effective. The live broadcast technology system includes four parts: signal recording, signal processing and scheduling, signal transmission and signal presentation and release. According to the similarities and differences of communication means and distribution channels, it can be divided into public IP streaming media live broadcast, private IP streaming media live broadcast, TV live broadcast and broadcast live broadcast. All the on-site signals are converted into IP streams by encoders, transmitted to various venues through public networks (4G networks and optical fiber private networks), and transmitted to various platforms through decoders in the main venue for live broadcast. The transmission network topology is shown in Figure 2.

5. Setting of core parameters

Multiple live broadcasts in different places are not only complicated, but also involve a large scale of personnel and equipment, making it difficult to coordinate command and dispatch. In order to ensure the stability and safety of the system and the orderly development of cooperative work, technicians test the main coding parameters and transmission network adopted by the system, so as to ensure that radio and television signals can work normally in the private network provided by telecom operators and ensure the safety and stability of live events.

The private telecommunication network in the main venue adopts the uplink and downlink bandwidth of 1000M, and the uplink and downlink bandwidth of each venue is 100M. Using STN and internal service address to realize point-to-point coding and decoding multicast of source-to-destination IP. In addition, the operator provides 100 m uplink and downlink private Internet access, provides public network IP separately and opens the following ports: 9000-90 10. The live TV signal is encoded by H.264, and the main parameters of the encoder are set as follows: video bit rate is 10 Mbps, GOP length is 12, buffer mode is CBR, GOP structure is ibbp, and audio PCR interval is 18. The audio coding standard is MPEG Layer2 with a bit rate of 256Kbps, the audio channel is stereo, the network protocol is IP encapsulation: UDP, and the IP packet is TS packet: 7 per IP packet. It is particularly important to note that in the audio settings of the encoder, AC3BYPASS needs to be set to OFF, otherwise the SDI interface of the encoder will only have a picture without sound. When configuring the codec, it should also be noted that the source IP is the encoder IP and the destination IP is the IP set by the decoder in TS over IP of NMS software (unlike the LCD panel IP of the decoder, the IP setting of the LCD panel corresponds to the management IP of NMS software).

Second, the experience summary

◆ The organizer takes the lead in setting up a leading group for live broadcast, coordinating all units to provide technical support, guarantee and service for live broadcast of activities, and defining the division of responsibilities;

◆ Determine the overall plan of the activity. Since the TV station itself has no optical fiber network transmission platform, the organizer should coordinate the operators to solve the problems of the distribution of video optical fiber dedicated lines between live broadcast points and the connection with the main venue after determining the location of each venue, and provide the use of STN platform, as well as the distribution, debugging and connection of optical fiber dedicated lines of venue data networks and internal high-speed networks;

◆ Basic emergency measures to prepare for live broadcast. If the live broadcast signal is guaranteed by primary and secondary channels, or even multi-channel signals, it is required to carry out technical tests before multi-channel broadcast to ensure smooth and non-interweaving, and to ensure mutual conversion when necessary; The live broadcast is relatively delayed, and problems are found and corrected in time; What happened to the live broadcast? Prepare still pictures or short videos related to live content, and block them in time.

◆ County stations support video guide switching and video shooting at the venue;

◆ Equipment system manufacturers support the debugging and operation guarantee of live streaming media systems and codecs in venues. It is precisely because of efficient command and dispatch, adequate preparation and debugging by professional and technical personnel that many live broadcasts can be successfully completed.

Three-point concluding remarks

The above is the scheme of live broadcast at different venues. This scheme has been successfully used in the broadcast of many important events, such as the torch relay of civilization, the Peach Blossom Festival and the marathon. The successful application of this scheme initiated the integration development of traditional media live broadcast and new media live broadcast, and received good social and economic benefits. In practical application, it meets the new requirements of live broadcast of major events, breaks through the time and space limitation of TV live broadcast in traditional multi-point remote live broadcast, and the system is more flexible, fast and convenient to implement. In the future, the exploration and application of new systems and technologies will be organized more effectively, and the process will be optimized to ensure that the system can be safer, more stable and more efficient in live broadcast; Fully combine the technical application of traditional media and new media, give full play to the advantages of media integration technology, and promote the deep integration of media.