stream-transcoding-overview

Stream transcoding

Change audio/video codecs, formats and bitrate of streams automatically and by REST request

Video stream transcoding is automatically enabled in one of the following cases:

  • The codecs of the streamer and player do not match by name.
  • H.264 codecs differ in the packetization-mode parameter.
  • The resolution of the player is explicitly indicated.
  • Explicitly specified player bitrate.

 

In addition, transcoding can be forced on the server. Turning off transcoding does not affect the mixer; when using a mixer, transcoding will be turned on.

Transcoding significantly increases the consumption of server resources (processor cores). Therefore, it should be turned on with caution!

Transcoding can be controlled using the REST API.

Specifications

Codecs Playback
technologies
Platforms
  • H.264
  • VP8
  • AAC
  • Speex
  • G.711
  • Opus
  • WebRTC
  • MSE
  • Flash
  • WSPlayer (Websocket + HTML5 Canvas)
  • Chrome
  • Firefox
  • Opera
  • Safari, Mac OS
  • Safari, iOS
  • IE
  • Edge
  • iOS SDK
  • Android SDK
Codecs
  • H.264
  • VP8
  • AAC
  • Speex
  • G.711
  • Opus
Playback technologies
  • WebRTC
  • MSE
  • Flash
  • WSPlayer (Websocket + HTML5 Canvas)
Platforms
  • Chrome
  • Firefox
  • Opera
  • Safari, Mac OS
  • Safari, iOS
  • IE
  • Edge
  • iOS SDK
  • Android SDK

Transcoding Scheme

The WCS server receives the video stream from the video stream source, changes the encoding parameters and transmits the transcoded stream to player (for playback).

scheme transcoding cdn webrtc browser WCS RESTAPI RESTcall webSDK codec bitrate

Step-by-step diagram of transcoding with REST API control

  1. Web Call Server receives audio/video stream
  2. REST client makes a request for transcoding the stream with the necessary parameters
  3. Web Call Server sends the transcoded stream to browser for playback

 

callflow transcoding cdn webrtc browser WCS RESTAPI RESTcall webSDK codec bitrate

For more information on testing transcoding, see page Testing