Expo 视频 (expo-av)

提供 API 以在应用中实现视频播放和录制的库。

Android

iOS

Web

Bundled version:

~15.1.7

已弃用：本页面记录的 expo-av 中的 Video 组件现已弃用，并由 expo-video 中的改进版本取代。了解 expo-video。

expo-av 中的 Video 组件显示与应用中其他 UI 元素内嵌的视频。

¥The Video component from expo-av displays a video inline with the other UI elements in your app.

许多视频和音频都有共同的 API，这些 API 记录在视音频文档中。本页涵盖视频特定的属性和 API。我们鼓励你浏览本文档以获取基本的视频功能，然后继续阅读视音频文档以获取更高级的功能。视频的音频体验（例如是否中断其他应用中已播放的音乐，或者是否在手机处于静音模式时播放声音）可以使用音频 API 进行自定义。

¥Much of Video and Audio have common APIs that are documented in AV documentation. This page covers video-specific props and APIs. We encourage you to skim through this document to get basic video working, and then move on to AV documentation for more advanced functionality. The audio experience of video (such as whether to interrupt music already playing in another app, or whether to play sound while the phone is on silent mode) can be customized using the Audio API.

安装

¥Installation

Terminal

- npx expo install expo-av

If you are installing this in an existing React Native app, make sure to install expo in your project.

用法

¥Usage

这是带有播放/暂停按钮的视频的简单示例。

¥Here's a simple example of a video with a play/pause button.

Video

import { useState, useRef } from 'react';
import { View, StyleSheet, Button } from 'react-native';
import { Video, ResizeMode } from 'expo-av';

export default function App() {
const video = useRef(null);
const [status, setStatus] = useState({});
return (
  <View style={styles.container}>
    <Video
      ref={video}
      style={styles.video}
      source={{
        uri: 'https://d23dyxeqlo5psv.cloudfront.net/big_buck_bunny.mp4',
      }}
      useNativeControls
      resizeMode={ResizeMode.CONTAIN}
      isLooping
      onPlaybackStatusUpdate={status => setStatus(() => status)}
    />
    <View style={styles.buttons}>
      <Button
        title={status.isPlaying ? 'Pause' : 'Play'}
        onPress={() =>
          status.isPlaying ? video.current.pauseAsync() : video.current.playAsync()
        }
      />
    </View>
  </View>
);
}

%%placeholder-start%%const styles = StyleSheet.create({ ... }); %%placeholder-end%%const styles = StyleSheet.create({
container: {
  flex: 1,
  justifyContent: 'center',
  backgroundColor: '#ecf0f1',
},
video: {
  alignSelf: 'center',
  width: 320,
  height: 200,
},
buttons: {
  flexDirection: 'row',
  justifyContent: 'center',
  alignItems: 'center',
},
});

有关更高级的示例，请查看播放列表示例和封装 <Video> 的自定义 VideoPlayer 控制组件，添加自定义控件并广泛使用 <Video> API。VideoPlayer 控件用于这个应用。

¥For more advanced examples, check out the Playlist example, and the custom VideoPlayer controls component that wraps <Video>, adds custom controls and use the <Video> API extensively. The VideoPlayer controls is used in this app.

API

import { Video } from 'expo-av';

Component

`Video`

Type: React.Component<VideoProps, VideoState>

The Video component props can be divided into following groups:

The source and posterSource props customize the source of the video content.
The useNativeControls, resizeMode, and usePoster props customize the UI of the component.
The onPlaybackStatusUpdate, onReadyForDisplay, and onIOSFullscreenUpdate props pass information of the state of the Video component.
The onLoadStart, onLoad, and onError props are also provided for backwards compatibility with Image (but they are redundant with onPlaybackStatusUpdate). Finally, the rest of props are available to control the playback of the video, but we recommend that, for finer control, you use the methods available on the ref described in the AV documentation.

VideoProps

`audioPan`

Optional • Type: number

The desired audio panning value of the audio for this media. This value must be between -1.0 (full left) and 1.0 (full right). See the AV documentation for more information.

`isLooping`

Optional • Type: boolean

A boolean describing if the media should play once (false) or loop indefinitely (true). See the AV documentation for more information.

`isMuted`

Optional • Type: boolean

A boolean describing if the audio of this media should be muted. See the AV documentation for more information.

`onError`

Optional • Type: (error: string) => void

A function to be called if load or playback have encountered a fatal error. The function is passed a single error message string as a parameter. Errors sent here are also set on playbackStatus.error that are passed into the onPlaybackStatusUpdate callback.

`onFullscreenUpdate`

Optional • Type: (event: VideoFullscreenUpdateEvent) => void

A function to be called when the state of the native iOS fullscreen view changes (controlled via the presentFullscreenPlayer() and dismissFullscreenPlayer() methods on the Video's ref).

`onLoad`

Optional • Type: (status: AVPlaybackStatus) => void

A function to be called once the video has been loaded. The data is streamed so all of it may not have been fetched yet, just enough to render the first frame. The function is called with the AVPlaybackStatus of the video as its parameter. See the AV documentation for further information.

`onLoadStart`

Optional • Type: () => void

A function to be called when the video begins to be loaded into memory. Called without any arguments.

`onPlaybackStatusUpdate`

Optional • Type: (status: AVPlaybackStatus) => void

A function to be called regularly with the AVPlaybackStatus of the video. You will likely be using this a lot. See the AV documentation for further information on onPlaybackStatusUpdate, and the interval at which it is called.

`onReadyForDisplay`

Optional • Type: (event: VideoReadyForDisplayEvent) => void

A function to be called when the video is ready for display. Note that this function gets called whenever the video's natural size changes.

`positionMillis`

Optional • Type: number

The desired position of playback in milliseconds. See the AV documentation for more information.

`PosterComponent`

Optional • Type:

React.ComponentType<{
  source: ImageProps[source], 
  style: ImageProps[style]
}>

A react-native Image like component to display the poster image.

`posterSource`

Optional • Type: ImageProps[source]

The source of an optional image to display over the video while it is loading. The following forms are supported:

A dictionary of the form { uri: 'http://path/to/file' } with a network URL pointing to an image file on the web.
require('path/to/file') for an image file asset in the source code directory.

`posterStyle`

Optional • Type: ImageProps[style]

An optional property to pass custom styles to the poster image.

`progressUpdateIntervalMillis`

Optional • Type: number

A number describing the new minimum interval in milliseconds between calls of onPlaybackStatusUpdate. See the AV documentation for more information.

`rate`

Optional • Type: number

The desired playback rate of the media. This value must be between 0.0 and 32.0. Only available on Android API version 23 and later and iOS. See the AV documentation for more information.

`resizeMode`

Optional • Type: ResizeMode

A string describing how the video should be scaled for display in the component view bounds. Must be one of the ResizeMode enum values.

`shouldCorrectPitch`

Optional • Type: boolean

A boolean describing if we should correct the pitch for a changed rate. If set to true, the pitch of the audio will be corrected (so a rate different than 1.0 will timestretch the audio). See the AV documentation for more information.

`shouldPlay`

Optional • Type: boolean

A boolean describing if the media is supposed to play. Playback may not start immediately after setting this value for reasons such as buffering. Make sure to update your UI based on the isPlaying and isBuffering properties of the AVPlaybackStatus. See the AV documentation for more information.

`source`

Optional • Type: AVPlaybackSource

The source of the video data to display. If this prop is null, or left blank, the video component will display nothing. Note that this can also be set on the ref via loadAsync(). See the AV documentation for further information.

See: The Android developer documentation and the iOS developer documentation lists of the video formats supported on Android and iOS.

`status`

Optional • Type: AVPlaybackStatusToSet

A dictionary setting a new AVPlaybackStatusToSet on the video. See the AV documentation for more information on AVPlaybackStatusToSet.

`useNativeControls`

Optional • Type: boolean

A boolean which, if set to true, will display native playback controls (such as play and pause) within the Video component. If you'd prefer to use custom controls, you can write them yourself, and/or check out the VideoPlayer component.

`usePoster`

Optional • Type: boolean

A boolean which, if set to true, will display an image (whose source is set via the prop posterSource) while the video is loading.

`videoStyle`

Optional • Type: StyleProp<ViewStyle>

An optional property to pass custom styles to the internal video component.

`volume`

Optional • Type: number

The desired volume of the audio for this media. This value must be between 0.0 (silence) and 1.0 (maximum volume). See the AV documentation for more information.

Inherited Props

ViewProps

Component Methods

`dismissFullscreenPlayer()`

This dismisses the fullscreen video view.

Returns:

Promise<AVPlaybackStatus>

A Promise that is fulfilled with the AVPlaybackStatus of the video once the fullscreen player has finished dismissing, or rejects if there was an error, or if this was called on an Android device.

`presentFullscreenPlayer()`

This presents a fullscreen view of your video component on top of your app's UI. Note that even if useNativeControls is set to false, native controls will be visible in fullscreen mode.

Returns:

Promise<AVPlaybackStatus>

A Promise that is fulfilled with the AVPlaybackStatus of the video once the fullscreen player has finished presenting, or rejects if there was an error, or if this was called on an Android device.

`setOnPlaybackStatusUpdate(onPlaybackStatusUpdate)`

Parameter	Type	Description
onPlaybackStatusUpdate	`null \| (status: AVPlaybackStatus) => void`	A function taking a single parameter `AVPlaybackStatus`.

Sets a function to be called regularly with the AVPlaybackStatus of the playback object.

onPlaybackStatusUpdate will be called whenever a call to the API for this playback object completes (such as setStatusAsync(), getStatusAsync(), or unloadAsync()), nd will also be called at regular intervals while the media is in the loaded state.

Set progressUpdateIntervalMillis via setStatusAsync() or setProgressUpdateIntervalAsync() to modify the interval with which onPlaybackStatusUpdate is called while loaded.

Returns:

void

Types

`VideoFullscreenUpdateEvent`

Property	Type	Description
fullscreenUpdate	`VideoFullscreenUpdate`	The kind of the fullscreen update.
status(optional)	`AVPlaybackStatus`	The `AVPlaybackStatus` of the video. See the AV documentation for further information.

`VideoNaturalSize`

Property	Type	Description
height	`number`	A number describing the height in pixels of the video data.
orientation	`'portrait' \| 'landscape'`	A string describing the natural orientation of the video data.
width	`number`	A number describing the width in pixels of the video data.

`VideoReadyForDisplayEvent`

Property	Type	Description
naturalSize	`VideoNaturalSize`	An object containing the basic data about video size.
status(optional)	`AVPlaybackStatus`	The `AVPlaybackStatus` of the video. See the AV documentation for further information.

`VideoState`

Property	Type	Description
showPoster	`boolean`	-

Enums

`ResizeMode`

`CONTAIN`

ResizeMode.CONTAIN ＝ "contain"

Fit within component bounds while preserving aspect ratio.

`COVER`

ResizeMode.COVER ＝ "cover"

Fill component bounds while preserving aspect ratio.

`STRETCH`

ResizeMode.STRETCH ＝ "stretch"

Stretch to fill component bounds.

`VideoFullscreenUpdate`

`PLAYER_WILL_PRESENT`

VideoFullscreenUpdate.PLAYER_WILL_PRESENT ＝ 0

Describing that the fullscreen player is about to present.

`PLAYER_DID_PRESENT`

VideoFullscreenUpdate.PLAYER_DID_PRESENT ＝ 1

Describing that the fullscreen player just finished presenting.

`PLAYER_WILL_DISMISS`

VideoFullscreenUpdate.PLAYER_WILL_DISMISS ＝ 2

Describing that the fullscreen player is about to dismiss.

`PLAYER_DID_DISMISS`

VideoFullscreenUpdate.PLAYER_DID_DISMISS ＝ 3

Describing that the fullscreen player just finished dismissing.

统一 API

¥Unified API

Video 组件 ref 上的其余 API 与 Audio.Sound 的 API 相同 - 请参阅视音频文档了解更多信息。

¥The rest of the API on the Video component ref is the same as the API for Audio.Sound - see the AV documentation for further information.