Video Conferencing Software With Support For Scalable Video Coding (svc) & Vp8 Codec

By Author: Winsent Clarke
Total Articles: 4
Comment this article

This year TrueConf Company released its video conferencing solutions with support for SVC. SVC is a technology of scalable video coding that allows transmitting video as basic or secondary streams in high quality or resolution. While coding video stream of higher quality can use data from the basic stream. SVC technology is a part of the compression standard H.264. To be more exact, SVC is correction to this standard, which was applied to provide high quality video that is streamed on networks with data loss. Video decoder uses the whole stream to transmit video in high quality. Still, if data loss happens to the secondary stream during transmission, decoder can continue decoding using data from the basic stream. Such approach reduces decoding artifacts, which are typical of standard codecs and appear when data loss.

Scalable Video Coding in Video Conferencing Software

TrueConf became the first company in the world that implemented SVC technology for VP8 video codec. It became an effective analogue to hardware video conferencing systems, which use conversion of video streams ...
... for each device. SVC technology allows video conferencing software server adjust image quality to the capabilities of the endpoint video conferencing devices. For example, smartphone with small screen will receive only basic stream with the lowest resolutions and lower bitrate, while a PC will receive the whole data in high quality. In fact, this technology partially takes upon itself the function of a standard MCU, but unlike it, SVC doesn't overload server CPU with decoding and repeated video coding processes.

Scaling Types

There are three main types of video streams scaling - temporal, spatial and qualitative.

- Temporal scaling (changed frame rate) - secondary stream is transmitted with higher frame rate. This type allows decoders to transmit the part or the whole frames set from the secondary stream.

- Spatial scaling (changed image size) - secondary stream is transmitted with higher video resolution. Decoder can be switched between different resolutions.

- Qualitative scaling (changed image quality) - secondary stream is encoded with better quality; decoder uses only the basic stream when secondary stream is not utilized.

In addition to these scaling types there is a combined one, which implements the combination of the approaches listed above, providing a server with a better potential to vary image quality and bitrate. Particularly this scaling type is realised in TrueConf Server to provide stable high-quality streaming during multipoint video conferencing sessions for participants using different video terminals.

TrueConf Team,

http://trueconf.com