1, the preface





















2. The author of this article







Bull: xian






IM real-time audio and video chat echo cancellation technology in detail


3. Reference to live broadcast technical articles



Brief discussion on the technical essentials of developing real-time video live broadcasting platform



To realize the practice sharing of 1080P real-time audio and video broadcast with a delay of less than 500 milliseconds



Practice of real-time video broadcast technology on mobile terminal: How to achieve real-time second open, smooth and smooth



Technology revealed: Facebook live video with millions of fans interacting



Detailed explanation of real-time audio and video broadcast technology on mobile terminal (I) : Introduction



Mobile terminal real-time audio and video broadcast technology details (ii) : acquisition



Mobile terminal real-time audio and video broadcast technology details (three) : processing



Mobile terminal real-time audio and video broadcast technology details (IV) : coding and packaging



Mobile terminal real-time audio and video broadcast technology details (five) : push stream and transmission



Mobile terminal real-time audio and video broadcast technology details (six) : delay optimization



Combine theory with practice: realize a simple real-time video live broadcast based on HTML5



Brief introduction to several key technical indicators that directly affect user experience in real-time audio and video live broadcast



First disclosure: How does Kuaishou achieve millions of viewers watching the live broadcast can still open seconds and no delay?



Android live introduction practice: start to build a simple live system



Some optimization ideas of netease Yunxin real-time video live broadcast in TCP data transmission layer



How P2P technology can reduce the bandwidth of live video broadcast by 75%?



More of the same…


4. Technical differences between live answering and traditional live answering









Livestreaming is an innovative way of answering questions based on traditional livestreaming. The differences from traditional livestreaming include the following points:









4.1 Massive concurrent assignment problems








4.2 Massive concurrent collection of questions








4.3 Video and answer synchronization








4.4 Background effects of the host





5. Live answering: a large number of concurrent sending and receiving questions
















First, let’s take a look at the business process of live answering questions:





  • The host issued the assignment instruction;
  • Subject information is delivered to users through real-time communication network and real-time distribution network.
  • VIP users pull topic information from real-time communication networks;
  • Ordinary users pull topic information from the real-time distribution network;
  • If the topic information contains the complete content, the next step is to query the topic content on the business server if only the topic ID is available.
  • The user submits the answer to the question to the answer statistical analysis server, and gets the standard answer feedback; Answer statistical analysis server is a distributed cluster, statistics answer results, feedback to the host.



Then, let’s look at the division of labor among the various web service entities:





  • Real-time communication network: A network designed for real-time transmission, capable of transmitting vast amounts of data, not just voice and video, in real time. Compared with real time distribution network (such as CDN), it has the characteristics of dynamic source return and weak network resistance.
  • Real-time distribution network: the network designed for real-time distribution of massive content, the advantage is that it can support massive concurrency, the cost is relatively low, the disadvantage is that the delay is higher than the real-time communication network;
  • Answer statistics service: a service designed outside the framework of live video for counting answers to questions submitted by users, which can feedback standard answers, count all answers to questions, and finally feed back to the host. The service should be able to withstand the pressure of massive concurrency;
  • Service server: If the assignment information contains the complete topic content, users do not need to query the topic content. If the assignment information is only the assignment ID, the user will go to the business server to query the assignment content. The service is also burdened with massive concurrency.


6. Key links in live answering








6.1 Massive concurrent issues




















6.2 Massive concurrent collection of questions




















6.3 Video and answer synchronization


























6.4 Security of topic content









According to the method of question delivery, there are two third-party live answer solutions in the market at present:





  • The first solution is that the technical solution sends all the content of the topic through the real-time voice and video channel. The advantage of this solution is that it is fully responsible for the security and concurrent pressure of the topic, and the developer does not need to invest in the development cost.
  • In the second scheme, the technical scheme only sends the title ID through the real-time voice and video channel. After the user terminal obtains the title ID, it queries the title content in the developer’s business server. The advantage of this solution is that the developer has complete control over the privacy of the subject content.



Take ZEGO’s live answer program as an example:





  • If the topic content is less than 1000 bytes, that is, 500 Chinese characters, all topic content can be transmitted through real-time voice and video channel;
  • If the number exceeds 1000 bytes, the topic ID is transmitted through the real-time voice and video channel, and the user terminal uses the topic ID to pull the topic content from the nearest server.





7. Write at the end









Click here to enter


Appendix: More live audio and video articles



[1] WebRTC: An open Source real-time audio and video technology



The status of open source real-time audio and video technology WebRTC



The advantages and disadvantages of open source real-time audio and video technology WebRTC are introduced



Interview with the Father of WebRTC standards: WebRTC past, Present and Future



WebRTC Zero-Base Developer Tutorial (Chinese)



WebRTC real-time audio and video technology overall architecture introduction



Getting started: What exactly is a WebRTC server and how does it connect calls?



WebRTC Real-time audio and video technology fundamentals: basic architecture and protocol stack



Brief discussion on the technical essentials of developing real-time video live broadcasting platform



Four reasons WebRTC should choose H.264 video encoding



Is it feasible to develop real-time audio and video based on open source WebRTC? What are the SDKS for party 3?



Application of RTP/RTCP data transmission protocol in WebRTC



This section describes the working principles of end-to-end encryption (E2EE) in real-time audio and video chat



Real-time communication RTC stack: video codec



Open source real-time audio and video technology WebRTC under Windows concise compilation tutorial



WebRTC: It looks beautiful, but how many holes do we have to fill?



More of the same…






[2] Other highlights of real-time audio and video development:



Instant messaging audio and video development (I) : a theoretical overview of video codec



Instant messaging audio and video development (ii) : digital video introduction to video codec



Instant messaging audio and video development (iii) : coding basis of video codec



Instant communication audio and video development (iv) : introduction to video codec predictive technology



Instant messaging audio and video development (5) : Understanding the mainstream video coding technology H.264



Instant messaging audio and Video development (vi) : How to start learning audio codec technology



Instant messaging audio and Video development (7) : Introduction to audio fundamentals and coding principles



Instant messaging audio and Video development (8) : common real-time voice communication coding standards



Instant messaging audio and Video development (ix) : Overview of echo and echo cancellation for real-time voice communications



Instant messaging audio and Video development (10) : real-time voice communication echo cancellation technology details



Instant communication audio and video development (11) : Real-time voice communication packet loss compensation technology details



Instant messaging audio and video development (12) : Multi-party real-time audio and video chat architecture discussion



Instant communication audio and Video development (13) : features and advantages of real-time video coding H.264



Instant communication audio and Video development (xiv) : Introduction of real-time audio and video data transmission protocols



Instant messaging audio and video development (15) : Talk about P2P and real-time audio and video applications



Instant Messaging audio and Video development (16) : Some suggestions for mobile real-time audio and video development



Instant communication audio and video development (17) : video coding H.264, VP8 past life



Brief introduction of audio processing and coding compression techniques in real-time voice chat



Netease Video Cloud technology sharing: Audio processing and compression technology quick start



Learn the basic knowledge of RFC3550: RTP/RTCP real-time transmission protocol



Research on Real-time Streaming Media Technology Based on RTMP Data Transfer Protocol



Audio Net Architect on difficulties in Implementing real-time Audio and Video Cloud (Video interview)



Brief discussion on the technical essentials of developing real-time video live broadcasting platform



Still testing real-time voice call quality with Hello hello? This article teaches you the scientific evaluation method!



To realize the practice sharing of 1080P real-time audio and video broadcast with a delay of less than 500 milliseconds



Practice of real-time video broadcast technology on mobile terminal: How to achieve real-time second open, smooth and smooth



How to test your live audio and video solution in the easiest way



Technology revealed: Facebook live video with millions of fans interacting



This section describes the working principles of end-to-end encryption (E2EE) in real-time audio and video chat



Detailed explanation of real-time audio and video broadcast technology on mobile terminal (I) : Introduction



Mobile terminal real-time audio and video broadcast technology details (ii) : acquisition



Mobile terminal real-time audio and video broadcast technology details (three) : processing



Mobile terminal real-time audio and video broadcast technology details (IV) : coding and packaging



Mobile terminal real-time audio and video broadcast technology details (five) : push stream and transmission



Mobile terminal real-time audio and video broadcast technology details (six) : delay optimization



Combine theory with practice: realize a simple real-time video live broadcast based on HTML5



IM real-time audio and video chat echo cancellation technology in detail



Brief introduction to several key technical indicators that directly affect user experience in real-time audio and video live broadcast



How to optimize the transmission mechanism to achieve ultra-low latency of real-time audio and video?



First disclosure: How does Kuaishou achieve millions of viewers watching the live broadcast can still open seconds and no delay?



Android live introduction practice: start to build a simple live system



Some optimization ideas of netease Yunxin real-time video live broadcast in TCP data transmission layer



Real-time audio and video chat technology sharing: anti-loss codec for unreliable networks



How P2P technology can reduce the bandwidth of live video broadcast by 75%?



Interview with the head of wechat video technology: Evolution of video chat technology in Micro-reliance



Tencent Audio and video Lab: using AI hacking technology to achieve ultra-low bit rate hd real-time video chat



Wechat team share: Decryption of the technology behind wechat’s daily 100 million real-time audio and video chats



Share the realization ideas and technical difficulties of the recently hot real-time live answering system



More of the same…