The "Cat Evening" on November 10, 2020 is another visual feast, full of double 11 ritual.
Since 2015, every year's cat nights have been built with huge sums of money, crowded with stars, and simultaneously distributed on multiple screens across the globe through broadcasting, TV, and the Internet.
It is not easy to bring this stage scenery of great artistic value to the mobile terminal through live broadcast technology, and even beyond the real sound effects and vision, but it is the persistent task of Alibaba Cloud Video Cloud.
As everyone knows, the Alibaba Cloud Video Cloud team has always played an important technical role in live broadcasts of heavyweight evenings such as Maowan. This is true this year and every year.
Specifically, Maowan has two major characteristics: the first is the ingenuity of the broadcast and television level. The meticulous arrangement, luxurious lineup, and cool stage effects can be called top live production. The second is the ultimate professional, professional actors and performances. At the same time, there are various professional equipments, such as lighting, photography, sound and mixing consoles, and a professional live production team.
To distribute this real-time party feast on multiple screens to all parts of the world, to ensure that the audience in front of the screen participate in the carnival and feel the atmosphere of the party, the technical indicators behind it need to meet at least three points: high reliability, high picture quality, and high sound quality.
First of all, high reliability. To ensure that every frame and sound of the party performance can be seen, heard, and felt by the audience in front of the screen, then in addition to the high reliability necessary for each cloud service, an end-to-end full link is required To ensure the high reliability of each link.
Furthermore, high picture quality and high sound quality. Such an ingenious evening party is required to be different from the general pan-entertainment anchor show. It not only pays attention to the visual enjoyment of the audience in front of the screen, but also must ensure their aural enjoyment, so that the audience in front of the screen must have a live viewing experience. .
How to achieve these technical indicators? Take a look at the technical solutions of Alibaba Cloud Video Cloud.
High reliability guarantee: end-to-end full link active and standby dual mechanism
Aiming at high reliability, Alibaba Cloud Video Cloud adopts an end-to-end full link active and standby dual mechanism to achieve. At the same time, it is worth emphasizing that Alibaba Cloud does not use two active and standby full links, but for each of the full links. Links, the main and standby dual mechanism reinsurance is realized. The main-backup dual mechanism can ensure that any jitter, stall or failure of the main device or the main link link will be immediately added to the backup link, so that the player is not aware of it, and it is possible to ensure smooth viewing.
Alibaba Cloud Video Cloud splits the entire link into three major links: the event site, Alibaba Cloud, and the user-side multi-screen playback terminal. (Shown below)
At the event site, there are mainly several modules for signal acquisition, processing, coding, and uploading. Among them, the signal collection and processing are ensured by the on-site production team to ensure high reliability, for example, by adding multiple professional equipment and professionals and multiple lines.
The encoding and uploading is the IP-based signal, which requires main and backup reinsurance to ensure the high reliability of this link. The signals produced on site need to be transmitted to the two main and standby encoders at the same time. The two encoders use the same set of signal sources and the same set of encoding parameters for encoding, and then upload them to Alibaba Cloud Live through multiple dedicated line networks of different operators. Service Center.
In the Alibaba cloud link, we adopt the technology of dual centers and multiple computer rooms, main and standby integration, seamless switching, resource isolation, and machine exclusive and redundant methods to ensure the high reliability of all links in the cloud. Among them, the dual-center and multi-computer rooms are for disaster tolerance, and the main and standby confluence is to ensure the flow of the main and standby links. The link with the optimal frame rate can be dynamically selected and seamlessly combined into one output.
At the same time, on the playback side, in addition to multi-screen distribution through more than 2,800 CDN nodes around the world, Alibaba Cloud Video Cloud also adopts a double-source, multi-bit-rate combination playback method in terms of playback technology, and integrates the playback terminal of Alibaba Cloud Play SDK , It can perform network adaptation to switch different transcoding grades according to the distribution network conditions, ensuring a very smooth viewing experience even when the network is not very good.
High sound quality guarantee: SRT access + full link Dolby
In terms of high sound quality, Alibaba Cloud Video Cloud uses SRT access and full-link Dolby audio technology to allow the audience in front of the screen to hear more real panoramic sound than the scene.
SRT protocol access is supported in the live link to ensure that the video stream of the broadcasting industry can be connected to the Internet for distribution with low latency and high reliability. SRT is a low-latency, high-reliability transmission protocol based on UDP. If you want to access one stream, you need to open the port, but the distinction between multiple streams can only be distinguished by port before, but now, Alibaba Cloud supports the streamID Ways to distinguish between different streams to access, thereby performing port multiplexing.
Users can use any push terminal device or software that supports SRT to directly push to the Alibaba Cloud edge node for use, such as the industry-wide OBS desktop software push terminal or other hardware SRT push devices. At the same time, Alibaba Cloud Video Cloud works closely with Haivision vendors, and also supports direct access to various hardware such as Haivision's Media Gateway and hardware encoders.
Alibaba Cloud Video Cloud uses Dolby Atmos technology to truly restore the live sound of the party. It supports end-to-end full-link Dolby audio transmission to ensure that the audio of each transcoding grade is also Dolby sound quality, making the screen in a bad network environment The former audience can also enjoy high-quality panoramic sound, and the feeling is even more real than the scene.
High quality guarantee: narrowband HD 2.0+FPGA265 encoding
In terms of high image quality, the unique narrowband HD 2.0 technology and FPGA265 encoding are used.
Alibaba Cloud Video Cloud Narrowband HD 2.0 technology starts from the human visual model and adjusts the video optimization goal from the classic "highest fidelity" to "best subjective experience". With a unique algorithm, it breaks through the upper limit of the capabilities of contemporary video encoders, while saving the bit rate, it can also provide a clearer viewing experience.
The FPGA265 encoder is used to ensure more savings in the bit rate. At the same time, the FPGA encoder can also provide better real-time compression performance to ensure that the bit rate of high-quality video is lower and the image quality is more real.
We know that H265 has a good compression ratio, but if you use CPU transcoding during live broadcast, it is difficult to achieve real-time, because the computational complexity of 265 is relatively high, and it is aimed at high resolution, high frame rate, and high bit rate video sources. , Using the CPU to do high-quality compression calculations to achieve 265 transcoding, real-time performance is almost impossible to guarantee, and the cost of the CPU machine is relatively high.
Therefore, the common practice in the industry tends to use GPU or FPGA to implement H265 real-time encoding with the help of hardware.
Dharma Academy’s XG Lab has meticulously created a real-time high-performance H265 FPGA hardware encoder “XGH265”, which has reached the top level in the industry in terms of compression effect and performance, and it also supports With configurable video pre-processing capabilities, the compression ratio and compression performance are the best in a clearer viewing experience.
In terms of compression performance, the compression performance of XGH265 is equivalent to the slowpreset level of X265. We need to know that it is very difficult to achieve the real-time compression performance of X265 slow for the 1080p source stream during the live broadcast. It is almost impossible to achieve in the industry's various GPU\FPGA and other hardware encoders. In real-time and image quality There can be no balance at the same time. And XGH265 is a rare low-grade FPGA card that can support 1080p 60fps in real-time and the compression performance is equivalent to X265. At present, Alibaba Cloud Dharma Academy XG Lab is proposing better solutions for 4K or even higher resolutions, which will be introduced to the market in the future.
From the dimensions of high reliability, high sound quality, and high picture quality, Alibaba Cloud Video Cloud provides an end-to-end full-link re-assurance solution to ensure that the live broadcast of major events such as cat night is stable, silky and immersive. territory.
Alibaba Cloud Video Cloud: Looking back at Maowan Live Broadcast for six years
From the time when Maowan first existed, that is, in 2015, the Alibaba Cloud Video Cloud team began to escort Maowan. During the period, the team also experienced many major events live broadcast.
Cai Ding, the technical leader of the project, said, “The team’s nervousness from the beginning to the orderly and unremarkable state of the day demonstrates the confidence of Video Cloud in the stability of its own cloud services. At the same time, the team aims at the end-to-end full chain The monitoring and warning of various indicators of the road, downgrading measures, emergency plan exercises, etc. have become more and more perfect."
For the escort, the Alibaba Cloud Video Cloud team also has corresponding strict escort manuals and regulations. All these improvements are polished through the review and iteration of the escort experience.
Cai Ding shared, “In the past, our escort was to watch the log while watching the monitoring, but currently we watch the live broadcast while watching the monitoring alarms. In the future, we even expect to be able to watch the live broadcast while shopping, just like other shoppers. We want to make the escort fully automated, and can automatically make various emergency plans and measures when encountering problems. At the same time, the business side can also use tools to protect itself, to maximize the automatic intelligent security of the entire chain. In short, we hope Every major event live broadcast is without surprises, without danger, plain and stable."
Video cloud technology capabilities for major festivals/event live broadcasts
Utilizing the end-to-end full-link re-protection solution, Alibaba Cloud Video Cloud can reuse the technology in more business scenarios, such as the Spring Festival Gala live broadcast, New Year's Day live broadcast, National Day military parade live broadcast, World Cup live broadcast, etc. , The 2018 World Cup live broadcast project is particularly profound and classic.
In supporting the live broadcast capabilities of large-scale evening parties, sports events, and competitive events, the outstanding advantages of Alibaba Cloud Video Cloud are: end-to-end full-link active and standby solutions, monitoring of various indicators, water level alarms, market monitoring, and visualized images A complete set of escort solutions that have been polished through many large-scale live events, such as combined screen staring, main and standby combined streaming, and frame rate code rate monitoring.
In the future, the technical solution has more room for upgrading. The person in charge of technology introduced, “At present, the full-link solution can only achieve 3-5 seconds of jitter on the main and backup links. We expect In the future, the ability to truly achieve seamless merging of the main and backup links at the frame level makes the playback end experience completely imperceptible, so that the end-to-end high-reliability full-link solution can achieve the broadcast-level protection effect.
Alibaba Cloud Video Cloud leads the forward-looking technology of the live broadcast industry, constantly exploring and upgrading, and looking forward to more visual feasts with immersive live broadcast experience.
The Alibaba Cloud Video Cloud Technology Official Account shares the video cloud industry and technology trends, creating "new content" and "new interactions."