In the 1998 World Cup, when Ronaldo lost his way in the final and France won the championship on home soil, Chinese fans could only reminisce about the football feast through the news and replays the next day. At a time when television was still a luxury, international events were video tapes for Chinese audiences, live texts in newspapers, and exciting commentary on the radio in the middle of the night.
With the advent and popularization of live streaming technology, international events such as the World Cup and the NBA are gradually becoming an indispensable part of the daily lives of Chinese audiences.
Large-scale sports events not only represent the pinnacle of sports competition, but also showcase the progress of media technology. In this era, live broadcast technology has become an important criterion to measure the level of media development in a country.
Nowadays, watching big events is no longer limited to one-way viewing, but has become more interactive and diverse. Enjoy the synchronous experience of "watching the game together", listen to the commentary of the big V, deeply understand the tactics and stories behind the event, and even experience the companionship of "celebrity watching".
The times are reincarnated, and it is time to test the live broadcast technology again.
On April 25, Agora released a new live broadcast solution, which supports millisecond-level low-latency global distribution, combined with multi-path and dynamic routing strategies, to provide ultra-low-latency, high-definition image quality live broadcast technology services for the live broadcast platform. This not only ensures the smoothness and clarity of the live broadcast of the event, but also reduces the platform cost and improves the audience experience through innovative technologies such as cloud commentary and low-code HD.
Signal transmission, entering the "golden age"
In that era when televisions were still rare, every time the Olympic Games, one TV set per village became the focus of the whole village, and men, women and children sat together, staring intently at the screen, witnessing the glory of the Chinese women's volleyball team. However, just as the girls of the women's volleyball team scored the decisive goal, the words "signal interruption" suddenly appeared on the screen, and the frustration and regret at that moment are still fresh in the memory of many older generation of sports fans.
Fast forward to today, and live streaming technology has changed dramatically. Faster, higher, and stronger, these three major needs have become the basic yardstick to measure whether the live broadcast technology meets the standard.
Here are a few examples that are visible to the naked eye. For example, if the sound and picture are out of sync, imagine that when you are nervously staring at the screen, expecting the player's kick, but the commentary voice is half a beat early, that sense of dislocation is enough to greatly reduce your viewing experience. The clarity of the video stream is also the focus of the audience's attention. In high-speed sporting events, any blurry moment can make you miss a crucial detail.
According to He Shengming, the technical director of Agora live broadcast, the live broadcast solution of Agora is based on NTP, which can ensure that all ends of the commentators are aligned, the difference in the live broadcast picture is strictly less than 3 frames, and the commentary audio track is synchronized with the event screen. Agora is also based on PTS technology, which solves the problem of smooth screen switching. Li Zhijie, the person in charge of Agora live broadcast products, said: "Agora's PTS alignment technology can ensure that most of the time, the audience's switching of the picture is smooth, the frames are continuous, and there will be no frame drops or missing frames.
In order to cope with the challenges of different network environments, Agora also adopts adaptive bitrate transmission (ABR) technology, which can dynamically adjust the transmission bitrate according to the network conditions of the audience, optimize the use of network resources, and effectively alleviate the unexpected problems caused by the audience's network fluctuations
At the same time, the clarity of the live broadcast screen is also the focus of the audience's attention. For example, the expression of the player, the moment when the football cuts across the net, and so on. Therefore, how to provide high-definition and smooth video streaming is a challenge that live streaming platforms must face.
But there is a technical paradox in the middle,The image quality itself is in conflict with no jamming,The higher the bit rate, the higher the definition,And the higher the bit rate, the higher the network requirements for the user,The higher the stuttering rate。 Maintaining both low code and HD requires a great deal of innovation in technology.
Agora uses low-code high-definition technology to efficiently compress video sources. By optimizing the encoding algorithm, Agora can greatly reduce the bitrate requirements of the video without sacrificing image quality. This technology is especially effective when dealing with high-speed sports footage, which can effectively capture the subtle expressions and movements of athletes while reducing the burden of network transmission due to high bitrates.
Secondly, the Agora live event streaming solution supports broadcast-grade 4K end-to-end stable transmission, and fully supports Huawei HDR Vivid, providing full-end rendering of static HDR and dynamic HDR. In addition, Agora's self-developed low-code high-definition technology and ABR solution have been added, which can greatly reduce the bitrate while improving the image quality.
Agora also uses deep learning algorithms to analyze the video content, and by identifying the key information and high-frequency signals in the video, the algorithm can optimize these areas during the encoding process. For example, in a live sports event, the algorithm prioritizes the clarity of key information such as the movement trajectory of players and balls, while the relatively static parts such as the background are encoded with a lower quality, thus balancing the overall image quality and bitrate.
More than these technical issues, the platform is a headache for security. With the development of network technology, the risk of video content being hotlink is also increasing. Once the content is hotlinked, not only the rights and interests of the platform will be infringed, but the audience's viewing experience will also be affected. Therefore, how to ensure the security of video content and avoid hotlink theft has become a difficult problem that live streaming platforms must face.
"When some platforms use traditional CDN services to broadcast World Cup matches, due to the lack of effective security protection measures, malicious third parties illegally cross-link live content. As a result, in just one day, about 2 Tbit/s of bandwidth was lost, causing an economic loss of up to one million yuan. Li Zhijie said.
It is in this context that Agora uses its military-grade signal encryption technology to realize the full encryption of the RTC (real-time communication) channel, ensuring that the signal content is strictly protected during the entire transmission process from the anchor to the audience. Agora's encryption technology not only covers the encryption at the transport layer, but also includes encryption at the content level, which means that even if the signal is illegally intercepted, the original content cannot be restored without the corresponding decryption key.
To put it simply, the low-latency transmission channel realizes end-to-end double encryption, that is, encryption during transmission and content encryption, adding a double lock to the security of live content. This encryption method effectively prevents hotlink events similar to those in the above cases, and ensures that the bandwidth resources and economic interests of the live streaming platform are not infringed.
Parades and military exercises with live streaming technology
With the continuous advancement of live streaming technology, users' viewing habits are also quietly changing. They're no longer content with a one-way viewing experience, but instead crave a more personalized and interactive way to live stream. Agora has insight into this trend, and through technological innovation, it continues to explore new scenarios for live broadcast to meet the diversified needs of users.
For example, invite friends to watch the live game online at the same time to celebrate the wonderful moment of scoring a goal. While enjoying ultra-low latency live matches, you can also chat with friends in real time by voice or video at any time. Or let the stars watch the events and variety shows with the audience in the form of interactive live video, providing the audience with an interactive companionship experience of "chasing more + chasing stars".
This is not only a technological innovation, but also a deep understanding of user needs.
Behind the above-mentioned scenarios are SD-RTN™, which optimizes the transmission path around the world through software technology to achieve low-latency and high-reliability audio and video data transmission.
The core advantage of SD-RTN™ lies in its intelligent routing and fault recovery capabilities. By monitoring the network status in real time, SD-RTN™ can automatically select the best transmission path to avoid congestion and unstable network areas, thereby reducing the latency of data transmission. In addition, it can quickly switch to an alternate path in the event of a network failure, ensuring continuity and stability of communication.
According to Li Zhijie, Agora has begun to cooperate with major platforms, and from this European Cup, users can enjoy the fastest live viewing experience on the whole network in the rooms of some platforms. It can ensure that the picture is transmitted to the audience's eyes within 500ms, which is up to 90% lower than the traditional HLS and FLV channels, and the first frame of the live broadcast screen on the viewer's side < 400ms, so that the wonderful event can be opened at any time. 80% of the audio and video packet loss boundary on the viewer side ensures smooth operation even on extremely weak networks.
More importantly, the cross-region transmission capability based on SD-RTN™ can provide significant cost savings for live streaming platforms. Traditional live streaming often relies on expensive private line services to ensure the stability and real-time performance of data transmission, which not only limits the flexibility of live broadcasting, but also brings high costs.
This means that live streaming platforms can use lower-cost Internet lines instead of expensive leased line services, significantly reducing transmission costs. The cloud-based commentary function eliminates the cost of renting offline venues, and also reduces the potential costs caused by space constraints.
In real-world application scenarios, SD-RTN™ is widely used in a variety of real-time interactive scenarios, including online education, telemedicine, and social live streaming. For example, in the live broadcast of international events, SD-RTN™ can ensure that global audiences can enjoy a low-latency, stutter-free viewing experience no matter where they are. In remote office scenarios, it supports the stable operation of multi-person video conferencing, and can maintain smooth communication even in poor network conditions.
This shows that the successful application of this technology indicates that live broadcast technology will penetrate into a wider range of fields and bring more far-reaching impact.
For example, in the field of e-sports, from the early "Warcraft" to today's "League of Legends", the popularity of game live streaming was limited by factors such as propagation power and bandwidth, and the low latency and high concurrent processing capabilities of SD-RTN™ can also help e-sports live broadcast reach a wider audience.
For live streaming platforms, technological innovation has brought about new modes of interaction. In the traditional live broadcast mode, problems such as hot mobile phones, unclear picture quality, and high cost have been plaguing the live broadcast industry. The launch of the cloud live streaming solution not only solves these problems by reducing the dependence on hardware, but also provides more possibilities for the selection of live broadcast equipment.
In the future, live streaming technology will face more complex and changing challenges. It not only needs to meet users' needs for high-definition, smooth, and real-time viewing, but also needs to be able to adapt to emerging new scenarios and applications. From live esports to online education, from telemedicine to social interaction, the tentacles of live streaming technology are constantly expanding, and its influence is gradually expanding.
"Higher, faster, stronger" is not only the spirit of sportsmanship, but also the long-term journey of live broadcast technology.