RTCRtpTransceiver.setCodecPreferences

The RTCRtpTransceiver method setCodecPreferences() configures the transceiver's codecs given a list of RTCRtpCodecParameters objects specifying the new preferences for each codec. The specified set of codecs and configurations will be used for all future connections including this transceiver until this method is called again.

When preparing to open an RTCPeerConnection, you can change the codec parameters from the user agent's default configuration by calling setCodecParameters() before calling either RTCPeerConnection.createOffer() or createAnswer().

Syntax

RTCRtpTransceiver.setCodecPreferences(codecs)

Parameters

codecs

An array of RTCRtpCodecParameters objects, in order of preference, each providing the parameters for one of the transceiver's supported codecs. If codecs is empty, the codec configurations are all returned to the user agent's defaults.

Note: Any codecs not included in codecs will not be considered during the process of negotiating a connection. This lets you prevent the use of codecs you don't wish to use.

Return value

undefined

Exceptions

InvalidAccessError

The codecs list includes one or more codecs which are not supported by the transceiver.

Usage notes

Getting a list of supported codecs

You can only include in the codecs list codecs which the transceiver actually supports. That means that either the associated RTCRtpSender or the RTCRtpReceiver needs to support every codec in the list. If any unsupported codecs are listed, the browser will throw an InvalidAccessError exception when you call this method.

To determine which codecs are supported by the transceiver, call the sender's getCapabilities() and the receiver's getCapabilities() methods and get the codecs list from the results of each.

This code shows how to get the lists of supported codecs for both sender and receiver:

var availSendCodecs = transceiver.sender.getCapabilities("video").codecs;
var availReceiveCodecs = transceiver.receiver.getCapabilities("video").codecs;

Specifications

Browser compatibilityUpdate compatibility data on GitHub

See also

• Introduction to the Real-time Transport Protocol (RTP)