files/en-us/web/api/rtcicecandidate/sdpmid/index.md
{{APIRef("WebRTC")}}
The read-only property sdpMid on the {{domxref("RTCIceCandidate")}} interface returns a string
specifying the media stream identification tag of the media component with which the candidate is associated.
This ID uniquely identifies a given stream for the component with which the candidate is associated.
This property can be configured by specifying the value of the sdpMid property in the candidateInfo options object that is passed to the {{domxref("RTCIceCandidate.RTCIceCandidate","RTCIceCandidate()")}} constructor.
If you call the constructor with an m-line string instead of the options object, the value of sdpMid is extracted from the specified candidate m-line string.
A string which uniquely identifies the source media component from
which the candidate draws data, or null if no such association exists for the candidate.
[!NOTE] Attempting to add a candidate (using {{domxref("RTCPeerConnection.addIceCandidate", "addIceCandidate()")}}) that has a value of
nullfor bothsdpMidandsdpMLineIndexwill throw a {{jsxref("TypeError")}} exception.
{{Specifications}}
{{Compat}}