RTCIceCandidateStats: priority property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

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.

Value

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.

Determining priority

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 (ptype is the priority of the candidate's type and plocal is the priority of the IP address):

priority=224×ptype+28×plocal+(256-componentID)\mathit{priority} = 2^{24} \times p_{type} + 2^{8} \times p_{local} + \left(\right. 256 - \mathit{componentID} \left.\right)

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

Specifications

Specification
Identifiers for WebRTC's Statistics API
# dom-rtcicecandidatestats-priority

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
priority in 'local-candidate' stats

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Full support
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See also