Reveal the Technical Hard Power behind the Live Broadcast of CCTV Spring Festival Gala (1)

At 8:00 p.m. on January 24th, 2020, the Spring Festival Gala of Year of the Rat began with Ode to the Spring Tide, a song and dance celebrating the new year. This is Hiphop, New Year Disco, the adapted version of Wild Wolf Disco (the first divine tune in 2019), Love of Dumplings in Wind and Snow, Go through the Motions and many other programs pushed the Spring Festival Gala to new highs.

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Opening picture of CCTV Spring Festival Gala (The picture is from screenshot on the website.)

The Spring Festival Gala of this year not only had a lot of actors, but also completely changed the hosts. All kinds of innovative programs were praised by audiences. This Spring Festival Gala could be called a visual feast of science and technology. The stage of the Spring Festival Gala created the three-dimensional stage design for the first time. At the same time, the flying screen technology was used to create a 360-degree surrounding landscape. Through excellent video production, the audiences could have the ultimate experience of "glasses-free 3D" in front of the screen.

Moreover, the main venue of the Spring Festival Gala of this year in Beijing interacted with branch venues in Guangdong-Hong Kong-Macao Greater Bay Area and Zhengzhou through 5G network. CCTV produced the 8K Ultra HD TV version of 2020 Spring Festival Gala for the first time, bringing unprecedented visual shock to audiences. The Spring Festival Gala of this year also cooperated with Kuaishou to launch red envelopes of the Spring Festival Gala of RMB1 billion. The peak network traffic of the Spring Festival Gala of this year created new high through the innovative linkage of small screen and big screen.

However, the continuous "flood peaks" of network traffic and the complex network environment were the ultimate test for the technical "logistics". In order to ensure the high-quality and stable broadcast of the Spring Festival Gala without freezing, as one of the backstage technology supporters of CCTV Spring Festival Gala of this year, Kingsoft Cloud helped the customers to improve "the fighting capacity" with more perfect technical services, comprehensively assisted with the live broadcast of CCTV Spring Festival Gala and Pay New Year's Call of Bilibili, fully supported Top 10 short video customers to win the hard battle, guaranteed tens of millions of interactive live broadcast with multiple technologies, and won the praise of users.


“Intelligent scheduling+selection of the best traffic inlet" assisted with the live broadcast of CCTV Spring Festival Gala

Over the years, the live broadcast of major events and activities, such as CCTV Spring Festival Gala, National People's Congress and Chinese People's Political Consultative Conference, the World Cup and other activities and sports events, have been guaranteed by Kingsoft Cloud. Kingsoft Cloud, which has passed the real test of live broadcast guarantee, has more technologies and experience in live broadcast guarantee.

In order to ensure that a large number of users could watch live programs of the Spring Festival Gala on cctv.cn synchronously and in HD, the team of Kingsoft Cloud made a detailed assessment of the bandwidth required by live broadcast in advance. At the same time, with its sufficient node resources and bandwidth resources, Kingsoft Cloud ensured a stable support for the peak bandwidth pressure formed by live broadcast. If the peak traffic exceeded the forecast, Kingsoft Cloud would add nodes to the customer's traffic scheduling group within one minute to expand the total capacity and meet the bandwidth demand.

The technical team of Kingsoft Cloud predicted that every hour after the Spring Festival Gala started at 20:00 would be the peak period of traffic. At the same time, combined with the business promotion content of major customers, the climax of user access caused by the red envelope snatching activity would appear. In order to ensure data traffic access with high concurrency and high QPS, Kingsoft Cloud adopted the intelligent scheduling system independently developed by it, which better guaranteed the realization of intelligent scheduling in the process of live broadcast.

The system includes three functional modules: load balancer, Kingsoft Cloud Eagle Eye and intelligent valve. The team of Kingsoft Cloud first monitors the data with "Kingsoft Cloud Eagle Eye" to see if the data has reached the "water level". If the "water level" is near, the "intelligent valve" will be opened, early warning and resource allocation will be made in advance, and then the traffic direction will be adjusted by the intelligent scheduling system, so as to realize the intelligent scheduling of traffic.

Kingsoft Cloud KVS, whose full name is KSyun Virtual Server, is a set of automatic load balancing system based on LVS R&D, transformation and optimization, characterized by high availability, good stability and strong scalability. Kingsoft Cloud KVS can set different weight values for each real server, so that resources with good performance can undertake more user requests and make reasonable use of existing resources. At the same time, Kingsoft Cloud KVS can also automatically inquire the load of real server and dynamically adjust the weight to make reasonable resource allocation.

In the process of live broadcast guarantee, on the basis of live broadcast source stations of CCTV and Kingsoft Cloud, a number of live broadcast source stations and transcoding clusters were established. The source traffic was pulled through RTMP/FLV, and HLS/HDS/FLV traffic pulling of CCTV was supported after transcoding. At the same time, it is equipped with the host and backup disaster recovery solution, which can backup each other among multiple source stations established, realize the second-level switch, and greatly transfer the high concurrent access requests of the source stations.

It is worth mentioning that Kingsoft Cloud took the lead in supporting over QUIC, the traffic pushing and pulling of live broadcast, in the industry. QUIC+solution for live broadcast of Kingsoft Video Cloud (The fluency still reached 96.51% when the packet loss rate was 30%) played an important role in this live broadcast guarantee.


CDN edge node of Kingsoft Cloud can realize the pre-pulling of the content of live broadcast

At the same time, Kingsoft Cloud uses CDN edge nodes to pre-pull the content of live broadcast, and pulls the content of live broadcast to the nearest edge node in advance, which can greatly reduce delay and greatly improve the playing experience of users. At the same time, Kingsoft Cloud has a "brain" on the edge node, which is responsible for distributing content, ensuring the load balance, providing the maximum service capacity, and reducing the pressure of source stations in the upper layer.

In addition, the team of Kingsoft Cloud adopted the industry's first technology of selection of the best traffic inlet in the guarantee process. That is to say, it allows the same live signal channel to inject into CDN at multiple points at the same time, ensures signal coexistence through alignment and arrangement of multiple original signal sources, senses the dithering of different signal sources in a timely manner through self-developed high-sensitivity dithering algorithm, selects the optimal signal source as the main signal for downward distribution on the scale of millisecond, and supports the smooth cutting of the optimal signal source at the level of millisecond without causing frame skip or repeated play. At the same time, with the strong support of the tested dynamic optimization of internal links of Kingsoft Cloud, it ensures the stable transmission of live broadcast signal in CDN.

"Intelligent scheduling system + source station diversion + pre-pulling of edge live broadcast content + multi-traffic optimization technology" jointly construct the technical strength of live video of Kingsoft Cloud, and also become the advantage of Kingsoft Cloud in the live broadcast architecture.