The MediaTrackConstraints dictionary's echoCancellation property is a ConstrainBoolean describing the requested or mandatory constraints placed upon the value of the echoCancellation constrainable property.

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.echoCancellation as returned by a call to MediaDevices.getSupportedConstraints(). However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.

Because RTP doesn't include this information, tracks associated with a WebRTC RTCPeerConnection will never include this property.

If this value is a simple true or false, the user agent will attempt to obtain media with echo cancellation enabled or disabled as specified, if possible, but will not fail if this can't be done. If, instead, the value is given as an object with an exact field, that field's Boolean value indicates a required setting for the echo cancellation feature; if it can't be met, then the request will result in an error.

See the Constraint exerciser example.

• Media Capture and Streams API
• Capabilities, constraints, and settings
• MediaTrackConstraints
• MediaDevices.getSupportedConstraints()
• MediaTrackSupportedConstraints
• MediaStreamTrack