MediaCapabilities.decodingInfo()

The MediaCapabilities.decodingInfo() method, part of the Media Capabilities API, returns a promise with the tested media configuration's capabilities info. This contains the three boolean properties supported, smooth, and powerefficient, which describe whether decoding the media described would be supported, smooth, and powerefficient.

Syntax

decodingInfo(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 three values:

file

Represents a configuration that is meant to be used for a plain file playback.

media-source

Represents a configuration that is meant to be used for playback of a MediaSource.

webrtc

Represents a configuration that is meant to be received using RTCPeerConnection.

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 decoded 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 decodingInfo() method is invalid, either because the type is not video or audio, the contentType is not a valid codec MIME type, the media decoding configuration is not a valid value for the type (file, media-source, or webrtc), or any other error in the media configuration passed to the method, including omitting any values.

Examples

This example shows how to create a media configuration for an audio file and then use it in MediaCapabilities.decodingInfo().

//Create media configuration to be tested
const mediaConfig = {
    type : 'file', // or 'media-source' or 'webrtc'
    audio : {
        contentType : "audio/ogg; codecs=vorbis", // valid content type
        channels : 2,     // audio channels used by the track
        bitrate : 132700, // number of bits used to encode 1s of audio
        samplerate : 5200 // number of audio samples making up that 1s.
     },
};

// check support and performance
navigator.mediaCapabilities.decodingInfo(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.`);
});

Similarly, the code below shows the configuration for a video file.

const mediaConfig = {
    type : 'file',
    video : {
        contentType : "video/webm;codecs=vp8", // valid content type
        width : 800,     // width of the video
        height : 600,    // height of the video
        bitrate : 10000, // number of bits used to encode 1s of video
        framerate : 30   // number of frames making up that 1s.
     }
};

Specifications

Specification
Media Capabilities
# ref-for-dom-mediacapabilities-decodinginfo

Browser compatibility

BCD tables only load in the browser

See also