媒体能力 API allows developers to determine decoding and encoding abilities of the device, exposing information such as whether media is supported and whether playback should be smooth and power efficient, with real time feedback about playback to better enable adaptive streaming, and access to display property information.
This example defines a audio configuration then checks to see if the user agent supports decoding that media configuration, and whether it will perform well in terms of smoothness and power efficiency.
if ('mediaCapabilities' in navigator) {
const audioFileConfiguration = {
type : 'file',
audio : {
contentType: "audio/mp3",
channels: 2,
bitrate: 132700,
samplerate: 5200
}
};
navigator.mediaCapabilities.decodingInfo(audioFileConfiguration).then(result => {
console.log('This configuration is ' +
(result.supported ? '' : 'not ') + 'supported, ' +
(result.smooth ? '' : 'not ') + 'smooth, and ' +
(result.powerEfficient ? '' : 'not ') + 'power efficient.')
})
.catch(() => {
console.log("decodingInfo error: " + contentType)
});
}
There are a myriad of video and audio codecs. Different browsers support different media types and new media types are always being developed. With the Media Capabilities API, developers can ensure each user is getting the best bitrate and storage savings for their browser, device, and OS capabilities.
Whether a device uses hardware or software decoding impacts how smooth and power efficient the video decoding is and how efficient the playback will be. The Media Capabilities API enables determining which codecs are supported and how performant a media file will be both in terms of smoothness and power efficiency.
The Media Capabilities API provide more powerful features than say
MediaRecorder.isTypeSupported()
or
HTMLMediaElement.canPlayType()
, which only address general browser support, not performance. The API also provides abilities to access display property information such as supported color gamut, dynamic range abilities, and real-time feedback about the playback.
To test support, smoothness and power efficiency of a video or audio file, you define the
media configuration
you want to test, and then pass the audio or video configuration as the parameter of the
MediaCapabilities
接口的
encodingInfo()
and
decodingInfo()
方法。
Media capabilities information enables websites to enable adaptative streaming to alter the quality of content based on actual user-perceived quality, and react to a pick of CPU/GPU usage in real time.
MediaCapabilities
Provides information about the decoding abilities of the device, system and browser based on codecs, profile, resolution, and bitrates. The information can be used to serve optimal media streams to the user and determine if playback should be smooth and power efficient.
MediaCapabilitiesInfo
mediaCapabilities
's
encodingInfo()
and
decodingInfo()
methods; returning whether the media configuration tested is supported, smooth, and powerEfficient.
Will describe the color gamut, or the range of color, the screen can display (not currently supported anywhere).
Will describe the known luminance characteristics of the screen (not currently supported anywhere).
MediaConfiguration
MediaCapabilities.encodingInfo()
and
MediaCapabilities.decodingInfo()
methods. It is inherited by the
MediaDecodingConfiguration
and
MediaEncodingConfiguration
字典。
MediaDecodingConfiguration
MediaCapabilities.decodingInfo()
. Consists of a media decoding type and a
VideoConfiguration
or
AudioConfiguration
字典。
MediaEncodingConfiguration
mediaCapabilities.encodingInfo()
. Consists of a media encoding type and a
VideoConfiguration
or
AudioConfiguration
字典。
VideoConfiguration
MediaConfiguration
参数用于
MediaCapabilities.encodingInfo()
and
MediaCapabilities.decodingInfo()
方法。
AudioConfiguration
MediaConfiguration
参数用于
MediaCapabilities.encodingInfo()
and
MediaCapabilities.decodingInfo()
方法。
| 规范 | 状态 | 注释 |
|---|---|---|
| Media Capabilities | 草案 | 初始定义 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
MediaCapabilities
|
Chrome 66 | Edge ≤79 | Firefox 63 | IE ? | Opera 55 | Safari ? | WebView Android 66 | Chrome Android 66 | Firefox Android 63 | Opera Android 48 | Safari iOS ? | Samsung Internet Android 9.0 |
decodingInfo
|
Chrome 66 | Edge ≤79 | Firefox 63 | IE ? | Opera 55 | Safari ? | WebView Android 66 | Chrome Android 66 | Firefox Android 63 | Opera Android 48 | Safari iOS ? | Samsung Internet Android 9.0 |
encodingInfo
|
Chrome
67
Disabled
|
Edge
≤79
Disabled
|
Firefox 63 | IE ? | Opera ? | Safari ? | WebView Android 不支持 No |
Chrome Android
67
Disabled
|
Firefox Android 63 | Opera Android ? | Safari iOS ? | Samsung Internet Android 不支持 No |
完整支持
不支持
兼容性未知
实验。期望将来行为有所改变。
用户必须明确启用此特征。
Navigator
interface