The WebRTC RTCIceCandidatePairStats dictionary reports statistics which provide insight into the quality and performance of an RTCPeerConnection while connected and configured as described by the specified pair of ICE candidates.

If a RTCStats-based object's type is candidate-pair, it's an RTCIceCandidatePairStats object.

RTCIceCandidatePairStats is based upon RTCStats and inherits its properties. In addition, it adds the following new properties:

availableIncomingBitrate Optional

Provides an informative value representing the available inbound capacity of the network by reporting the total number of bits per second available for all of the candidate pair's incoming RTP streams. This does not take into account the size of the IP overhead, nor any other transport layers such as TCP or UDP.

availableOutgoingBitrate Optional

Provides an informative value representing the available outbound capacity of the network by reporting the total number of bits per second available for all of the candidate pair's outgoing RTP streams. This does not take into account the size of the IP overhead, nor any other transport layers such as TCP or UDP.

bytesReceived Optional

The total number of payload bytes received (that is, the total number of bytes received minus any headers, padding, or other administrative overhead) on this candidate pair so far.

bytesSent Optional

The total number of payload bytes sent (that is, the total number of bytes sent minus any headers, padding, or other administrative overhead) so far on this candidate pair.

currentRoundTripTime Optional

A floating-point value indicating the total time, in seconds, that elapsed between the most recently-sent STUN request and the response being received. This may be based upon requests that were involved in confirming permission to open the connection.

lastPacketReceivedTimestamp Optional

A DOMHighResTimeStamp value indicating the time at which the last packet was received by the local peer from the remote peer for this candidate pair. Timestamps are not recorded for STUN packets.

lastPacketSentTimestamp Optional

A DOMHighResTimeStamp value indicating the time at which the last packet was sent from the local peer to the remote peer for this candidate pair. Timestamps are not recorded for STUN packets.

localCandidateId Optional

The unique ID string corresponding to the RTCIceCandidate from the data included in the RTCIceCandidateStats object providing statistics for the candidate pair's local candidate.

nominated Optional

A Boolean value which, if true, indicates that the candidate pair described by this object is one which has been proposed for use, and will be (or was) used if its priority is the highest among the nominated candidate pairs. See RFC 5245, section 7.1.3.2.4 for details.

remoteCandidateId Optional

The unique ID string corresponding to the remote candidate from which data was taken to construct the RTCIceCandidateStats object describing the remote end of the connection.

requestsReceived Optional

The total number of connectivity check requests that have been received, including retransmissions. This value includes both connectivity checks and STUN consent checks.

requestsSent Optional

The total number of connectivity check requests that have been sent, not including retransmissions.

responsesReceived Optional

The total number of connectivity check responses that have been received.

responsesSent Optional

The total number of connectivity check responses that have been sent. This includes both connectivity check requests and STUN consent requests.

state Optional

A string which indicates the state of the connection between the two candidates.

totalRoundTripTime Optional

A floating-point value indicating the total time, in seconds, that has elapsed between sending STUN requests and receiving responses to them, for all such requests made to date on this candidate pair. This includes both connectivity check and consent check requests. You can compute the average round trip time (RTT) by dividing this value by responsesReceived.

transportId Optional

A string that uniquely identifies the RTCIceTransport that was inspected to obtain the transport-related statistics (as found in RTCTransportStats) used in generating this object.

The following properties have been removed from the specification and should no longer be used. You should update any existing code to avoid using them as soon as is practical. Check the compatibility table for details on which browsers support them and in which versions.

priority Deprecated Optional

An integer value indicating the candidate pair's priority.

readable Deprecated Optional Non-standard

A Boolean value indicating whether or not data can be sent over the connection described by the candidate pair.

writable Deprecated Optional Non-standard

A Boolean value indicating whether or not data can be received on the connection described by the candidate pair.

selected Non-standard Optional

A Firefox-specific Boolean value which is true if the candidate pair described by this object is the one currently in use. The spec-compliant way to determine the selected candidate pair is to look for a stats object of type transport, which is an RTCTransportStats object. That object's selectedCandidatePairId property indicates whether or not the specified transport is the one being used.

The currently-active ICE candidate pair—if any—can be obtained by calling the RTCIceTransport method getSelectedCandidatePair(), which returns an RTCIceCandidatePair object, or null if there isn't a pair selected. The active candidate pair describes the current configuration of the two ends of the RTCPeerConnection.

Any candidate pair that isn't the active pair of candidates for a transport gets deleted if the RTCIceTransport performs an ICE restart, at which point the state of the ICE transport returns to new and negotiation starts once again. For more information, see ICE restart.

This example computes the average time elapsed between connectivity checks if the RTCStats object rtcStats is an RTCIceCandidatePairStats object.

if (rtcStats && rtcStats.type === "candidate-pair") {
  let elapsed =
    (rtcStats.lastRequestTimestamp - rtcStats.firstRequestTimestamp) /
    rtcStats.requestsSent;

  log(`Average time between ICE connectivity checks: ${elapsed} ms.`);
}

The code begins by looking at rtcStats to see if its type is candidate-pair. If it is, then we know that rtcStats is in fact an RTCIceCandidatePairStats object. If so, we compute the average time elapsed between STUN connectivity checks and log that information.