What is the WebRTC server?
In the early WebRTC one of the main selling points of this technology is that it allows the point (browser to browser) communication, almost no server intervention, normally only used for signaling server (such as proxy for the connection). In this application stage, the concept of a dedicated WebRTC media server seemed a bit redundant.
But with WebRTC application scenarios become complex, such as online video conference, this time to point communication experience problems. Now, I will try to explain why, for example video conferencing media server can be useful, they often provide what open source alternative to what type of functions and users can use.
The figure is a point to point network architecture based video conferencing systems,
While holding video call can communicate with a plurality of other participants, but as the number of participants increases, it is no longer practical because of the requirement peer sends his / her video / audio stream to each of the participants, while each participant received video / audio stream.
Indeed, even in the tuning network conditions, the mesh becomes difficult in a video call participant after more than five. In order to solve such a performance bottleneck, it introduces the concept of additional media server (Media Server) is. Because a centralized forwarding architecture approach helps reduce the amount of flow of the client needs to be sent, usually only need to send one stream can even reduce the number of clients that need to receive, depending on which media server functionality. Of course, at the cost of a corresponding increase in server costs.
When acting as a media server that the media relay, it is often referred to as SFU (Selective Forwarding Unit selective forwarding unit), which means that its main purpose is to forward the media stream between the client. There the concept of a MCU (Multipoint Conferencing Unit multipoint conference unit), the MCU server not only forwards but also for mixed media stream compression and coding (such as data forwarding each client packaging, and SFU compared, so that a large reducing the amplitude of the forwarding data bandwidth requirements, but have higher requirements on the CPU).
In short, the benefits of media servers are as follows:
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It extends the system performance and functionality to support more complex scenarios;
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All the benefits of the media stream through a media server that can be recorded, which for the minutes of the meeting of the need to retain some of the scenes is very useful;
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And can easily integrate third-party systems, such as Web systems and SIP phone systems (such as Asterisk to build applications between);
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Additional processing can be performed on the media stream, such as podcasts to add to the virtual hat Face Recognition artificial intelligence.
What open source media server is available?
Jitsi Platform
Jitsi not only WebRTC media server, but also a complete platform. Jitsi products include Jitsi Videobridge (media relay, SFU), Jitsi Meet (conference network clients), Jicofo (Jitsi Conference Focus), Jigasi (Jitsi Gateway to SIP) and Jitsi SIP Phone. With Jitsi we can quickly build a complete communications platform available within a few hours. It also uses Jingle (XMPP) and full-featured Web interface to achieve their signaling control. However, regrettably, it does not provide for media recording solutions for stable and easy to use.
Current Media Server
This is one of the most versatile solutions. It is not only a media server, and is a development kit. Kurento main advantage lies in its versatility, the concept of media workflow allows defining how and where in the code the media stream. This allows developers to WebRTC combination and integration of very interesting features such as augmented reality, AR computer vision (such as a QR code recognition, face detection), and modify real-time media and RTP (VoIP) service interoperability. Kurento can be configured to SFU or MCU, or both.
Janus Gateway WebRTC
Although its description did not mention the "Media Server" in any place, but Janus can easily be set to SFU. One of its most notable feature is its plug-in architecture can enhance the core functionality of the service. Janus has some interesting use cases, such as SIP Gateway, screen sharing and so on.
mediasoup
This is a relatively new and interesting media server, which other media servers difference is that it is designed as a development library for Node, which allows it to be easily integrated into a larger application.