SVC (Scalable Video Coding)

SVC (Scalable Video Coding) is a video conferencing architecture based on scalable video coding. Here’s how it works:

  1. The client forms an SVC stream by compressing video stream layers by layers and sends it to the video conferencing server. The number of layers in a video stream to be sent depends on the width of the connection channel and bandwidth.
  2. The server processes obtained SVC streams from all the clients and removes extra layers without recording.
  3. The server returns processed video streams to each client.
  4. The client forms a conference layout.

SVC (Scalable Video Coding) 1

SVC technology generates multiple video stream layers: from the main stream (with the lowest bitrate) to many additional layers, allowing to drastically improve the final picture quality on compatible devices. At the same time, not only the total bitrate increases, but it is also possible to raise the video frame rate (for example, from 15 fps to 60), boost the resolution to 4K and adjust the compression ratio.

SVC (Scalable Video Coding) 2And it’s all available in automatic mode. For example, when changing the video layout, the window that was the main one, and then reduced in size, begins to receive a smaller thread. This is how the server reacts to changes in the window’s resolution. The same applies in both directions: when the window is zoomed in, the video quality increases.

This works for all conference participants to avoid situations where the maximum video quality is limited to the user with the weakest client. Each receives a data stream that fits his device and channel width.

SVC (Scalable Video Coding) 3For SVC support there is no need for a powerful, expensive server, just an ordinary computer with a modern processor. The technology is so optimized in stream encoding that the number of participants in a video conference can reach several thousands people.

Comparison: 16-point conference, on the client

Outgoing streams 1 1
Incoming streams 1 15
Out channel, Mb/s 1,0 1,2
Incoming channel, Mb/s 1,0 1,2
CPU load 20% 70%

Comparison: 16 participants, on the server

Outgoing streams 16 240
Incoming streams 16 16
Out channel, Mb/s 16,0 19,2
Incoming channel, Mb/s 16,0 19,2
vCPU load 1600% 0%

In terms of network load, a set of threads differs from a single thread (as in MCU) by 20-30%. There is no redundancy, as SVC multilayer allows selecting a thread very precisely for the resolution chosen by the user.

SVC (Scalable Video Coding) 4

SVC-based systems have all advantages of mixing architectures and at the same time are deprived of multiplexing systems’ faults. They are cheap, cross-platform and easily scalable.

You can also learn more about other video conferencing architecture types on our website.