RTCIceCandidateStats.priority

The RTCIceCandidateStats dictionary's priority property is a positive integer value indicating the priority (or desirability) of the described candidate.

During ICE negotiation while setting up a WebRTC peer connection, the priority values reported to the remote peer by a user agent are used to determine which candidates are considered "more desirable". The higher the value, the more desirable the candidate is.

A positive integer indicating the priority of the RTCIceCandidate described by the RTCIceCandidateStats object. The value may be anywhere from 1 to 2,147,483,647.

The ICE specification describes how user agents and other software using WebRTC should calculate the priority. The priority of a candidate is calculated using the following variables as inputs:

• The preferability of the candidate type (local, server reflexive, peer reflexive, or relayed)
• The preferability of the candidate's specific IP address (for multihomed agents)
• The candidate's component ID (1 for RTP, 2 for RTCP)

The candidate's priority is computed using the formula (p_type is the priority of the candidate's type and p_local is the priority of the IP address):

$$priority\quad =\quad { 2 }^{ 24 }\times { p }$${ type }\quad +\quad { 2 }^{ 8 }\times { p }{ local }\quad +\quad (256\quad -\quad componentID)

This is equivalent to mapping the priorities of teh candidate type, the local IP, and the component ID into various bit ranges within the 32-bit priority value.

• RFC 5245: 4.1.2.1: Recommended Formula section in the ICE specification