RTCPeerConnection.createAnswer()

The createAnswer() method of the RTCPeerConnection interface is used by the recipient of an offer to create an answer to return to the peer which initiated the offer. This is part of the two-part offer/answer negotiation of a WebRTC peer connection.

Syntax

aPromise = RTCPeerConnection.createAnswer([options]);

RTCPeerConnection.createAnswer(successCallback, failureCallback);

Parameters

options Optional

An RTCAnswerOptions dictionary providing options for the answer.

RTCAnswerOptions dictionary

The RTCAnswerOptions dictionary is used to customize the answer.

voiceActivityDetection Optional

Some codecs and hardware are able to detect when audio begins and ends by watching for "silence" (or relatively low sound levels) to occur. This reduces network bandwidth used for audio by only sending audio data when there's actually something to broadcast. However, in some cases, this is unwanted. For example, in the case of music or other non-voice transmission, this can cause loss of important low-volume sounds. Also, emergency calls should never cut audio when quiet. This option defaults to true (voice activity detection enabled).

Deprecated parameters

successCallback

An RTCSessionDescriptionCallback which accepts as an input an RTCSessionDescription representing the SDP answer to then be sent to the other peer.

failureCallback

An RTCPeerConnectionErrorCallback which receives a DOMException specifying the cause of the failure. This may be any of the exceptions listed under Exceptions.

Exceptions

NotReadableError

The identity provider wasn't able to provide an identity assertion.

OperationError

Generation of the SDP failed for some reason; this is a general failure catch-all exception.

Return value

A Promise which when fulfilled returns a RTCSessionDescription representing the answer which is to be delivered to the other peer

Specifications

Browser compatibility

[1] A callback-based version of this method was deprecated in Chrome 49.

[2] The callback-based version of this method was deprecated in Firefox 37.