SDP signaling and negotiation for media plane
Read more on SDP and its attributes : https://telecom.altanai.com/2014/01/03/sip-in-depth/(opens in a new tab)
Media plane adaptation is done at the SBC for network carried media, it should be done for all network hosted media services which face peer-to-peer media.
The high-level architecture elements of WebRTC media streams can be divided into two areas:
Adaptation of WebRTC Media Plane to IMS Media Plane
Encryption, RTP Multiplexing, Support for ICE
Audio – Interworking of differing WebRTC and codec sets
Video – Use of VP8 , Support for H.264
Data – Support of MSRP ( RCS standard for messaging over DataChannel API)
Peer-to-Peer Media
Direct connection to media servers and media gateways .
Use common codec set wherever possible to eliminate transcoding Use regionalized transcoding where common codec not available Note: Real-time video transcoding is expensive and performance impacting
On-going standards/device/network work needs to be done to expand common codec set. WebRTC codec standards have not been finalized yet. WebRTC target is to support royalty free codecs within its standards.
| Media | WebRTC | legacy |
| Audio | G.711, Opus | G.711, AMR, AMR-WB (G.722.2) |
| Audio – Extended | G.729a[b], G.726 | |
| Video | VP8 | H.264/AVC |
Supporting common codecs between VoLTE devices and WebRTC endpoints requires one or more of the following: 1.Support of WebRTC codecs on 3GPP/GSMA 2.Support of 3GPP/GSMA codecs on WebRTC 3.WebRTC browser support of codecs native to the device
References :
https://tools.ietf.org/id/draft-ietf-rtcweb-sdp-08.html#rfc.section.5.2.8
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