MediaCapabilities: encodingInfo() method

Available in workers

The encodingInfo() method of the MediaCapabilities interface returns a promise that fulfills with the tested media configuration’s capabilities for encoding media. This contains the three boolean properties supported, smooth, and powerefficient, which describe how compatible the device is with the type of media.

Syntax

encodingInfo(configuration)

Parameters

• configuration
  • : An object with a property type and either a video or audio property containing a configuration of the appropriate type:

    • type

      • : The type of media being tested. This takes one of two values:
        • record
          • : Represents a configuration for recording of media, e.g., using MediaRecorder.
        • webrtc
          • : Represents a configuration meant to be transmitted over electronic means (e.g., using RTCPeerConnection).
        • transmission
          • : A synonym of webrtc.

    • video

      • : Configuration object for a video media source. This has the following properties:
        • contentType
          • : String containing a valid video MIME type, and (optionally) a codecs parameter.
        • width
          • : The width of the video.
        • height
          • : The height of the video.
        • bitrate
          • : The number of bits used to encode one second of the video file.
        • framerate
          • : The number of frames making up one second of video playback.

    • audio

      • : Configuration object for an audio media source. This has the following properties:
        • contentType
          • : String containing a valid audio MIME type, and (optionally) a codecs parameter.
        • channels
          • : The number of channels used by the audio track.
        • bitrate
          • : The number of bits used to encode one second of the audio file.
        • samplerate
          • : The number of audio samples making up one second of the audio file.

Return value

A Promise fulfilling with an object containing three Boolean attributes:

• supported
  • : true if the media content can be encoded at all. Otherwise, it is false.
• smooth
  • : true if playback of the media will be smooth (of high quality). Otherwise it is false.
• powerEfficient
  • : true if playback of the media will be power efficient. Otherwise, it is false.

Browsers will report a supported media configuration as smooth and powerEfficient until stats on this device have been recorded. All supported audio codecs are reported to be power efficient.

Exceptions

• TypeError
  • : Thrown if the configuration passed to the encodingInfo() method is invalid, which may be for any of the following reasons:
    • the type is not video or audio,
    • the contentType is not a valid codec MIME type,
    • there is some other error in the media configuration passed to the method, including omitting any of the configuration elements.

Examples

Setting a media configuration

// Create media configuration to be tested
const mediaConfig = {
  type: "record",
  video: {
    contentType: "video/webm;codecs=vp8.0", // valid content type
    width: 1920, // width of the video
    height: 1080, // height of the video
    bitrate: 120000, // number of bits used to encode 1s of video
    framerate: 48, // number of frames making up that 1s.
  },
};

// check support and performance
navigator.mediaCapabilities.encodingInfo(mediaConfig).then((result) => {
  console.log(
    `This configuration is ${result.supported ? "" : "not "}supported,`,
  );
  console.log(`${result.smooth ? "" : "not "}smooth, and`);
  console.log(`${result.powerEfficient ? "" : "not "}power efficient.`);
});

Specifications

Browser compatibility

See also

• decodingInfo()