React-native:如何在expo-av中改变音频速度

Question

我在改变prop: 'rate'来改变正在播放的音频的速度时遇到了麻烦。

我使用的是expo-av (https://docs.expo.dev/versions/latest/sdk/av/)。

下面是我的代码:

import {Text, View, Alert } from 'react-native'
import * as MediaLibrary from 'expo-media-library';
import { DataProvider } from 'recyclerlistview';
import {Audio} from 'expo-av';
import { play, pause, resume, playNext } from "../misc/AudioController";
export const AudioContext = createContext()
export class AudioProvider extends Component {
constructor(props) {
super(props);
this.state = {
audioFiles: [],
permissionError: false,
dataProvider: new DataProvider((r1, r2) => r1 !== r2),
playbackObj: null,
soundObj: null,
currentAudio: {},
isPlaying: false,
currentAudioIndex: null,
playbackPosition: null,
playbackDuration: null,
rate: 2.0,
};
this.totalAudioCount = 0;
}
permissionAlert = () => {
Alert.alert("Permission Required", "This app needs to read audio files", [
{ text: "I am ready", onPress: () => this.getPermission() },
{
text: "cancel",
onPress: () => this.permissionAlert(),
},
]);
};
getAudioFiles = async () => {
const { dataProvider, audioFiles } = this.state;
let media = await MediaLibrary.getAssetsAsync({
mediaType: "audio",
});
media = await MediaLibrary.getAssetsAsync({
mediaType: "audio",
first: media.totalCount,
});
this.totalAudioCount = media.totalCount;
this.setState({
...this.state,
dataProvider: dataProvider.cloneWithRows([
...audioFiles,
...media.assets,
]),
audioFiles: [...audioFiles, ...media.assets],
});
};
loadPreviousAudio = async () => {
let previousAudio = await AsyncStorageLib.getItem("previousAudio");
let currentAudio;
let currentAudioIndex;
if (previousAudio === null) {
currentAudio = this.state.audioFiles[0];
currentAudioIndex = 0;
} else {
previousAudio = JSON.parse(previousAudio);
currentAudio = previousAudio.audio;
currentAudioIndex = previousAudio.index;
}
this.setState({ ...this.state, currentAudio, currentAudio });
};
getPermission = async () => {
//    {
//    "canAskAgain": true,
//    "expires": "never",
//    "granted": false,
//    "status": "undetermined",
//    }
const permission = await MediaLibrary.getPermissionsAsync();
if (permission.granted) {
this.getAudioFiles();
}
if (!permission.canAskAgain && !permission.granted) {
this.setState({ ...this.state, permissionError: true });
}
if (!permission.granted && permission.canAskAgain) {
const { status, canAskAgain } =
await MediaLibrary.requestPermissionsAsync();
if (status === "denied" && canAskAgain) {
this.permissionAlert();
}
if (status === "granted") {
this.getAudioFiles();
}
if (status === "denied" && !canAskAgain) {
this.setState({ ...this.state, permissionError: true });
}
}
};

onPlaybackStatusUpdate = async (playbackStatus) => {
console.log("hier");
if (playbackStatus.isLoaded && playbackStatus.isPlaying) {
this.updateState(this, {
playbackPosition: playbackStatus.positionMillis,
playbackDuration: playbackStatus.durationMillis,
});
}
if (playbackStatus.didJustFinish) {
const nextAudioIndex = this.state.currentAudioIndex + 1;
if (nextAudioIndex >= this.totalAudioCount) {
this.state.playbackObj.unloadAsync();
this.updateState(this, {
soundObj: null,
currentAudio: this.state.audioFiles[0],
isPlaying: false,
currentAudioIndex: 0,
playbackPosition: null,
playbackDuration: null,
});
}
const audio = this.state.audioFiles[nextAudioIndex];
const status = await playNext(this.state.playbackObj, audio.uri);
this.updateState(this, {
soundObj: status,
currentAudio: audio,
isPlaying: true,
currentAudioIndex: nextAudioIndex,
});
}
};
componentDidMount() {
this.getPermission();
if (this.state.playbackObj === null) {
this.setState({ ...this.state, playbackObj: new Audio.Sound(), });
}
}
updateState = (prevState, newState = {}) => {
this.setState({ ...prevState, ...newState });
};
render() {
const {
audioFiles,
dataProvider,
permissionError,
playbackObj,
soundObj,
currentAudio,
isPlaying,
currentAudioIndex,
playbackPosition,
playbackDuration,
rate,
} = this.state;
if (permissionError)
return (
<View
style={{
flex: 1,
justifyContent: "center",
alignItems: "center",
}}
>
<Text>It looks like you haven't accepted the permission</Text>
</View>
);
return (
<AudioContext.Provider
value={{
audioFiles,
dataProvider,
playbackObj,
soundObj,
currentAudio,
isPlaying,
currentAudioIndex,
totalAudioCount: this.totalAudioCount,
playbackPosition,
playbackDuration,
rate,
updateState: this.updateState,
loadPreviousAudio: this.loadPreviousAudio,
onPlaybackStatusUpdate: this.onPlaybackStatusUpdate
}}
>
{this.props.children}
</AudioContext.Provider>
);
}
}

import {Component} from 'react';
import AsyncStorageLib from '@react-native-async-storage/async-storage';
export default AudioProvider;

还有一些

// play audio
// Import the react-native-sound module
import { PitchCorrectionQuality,shouldCorrectPitch, rate } from "expo-av/build/AV.types";
export const play = async (playbackObj, uri,) => {
try {
return await playbackObj.loadAsync(
{uri}, 
{shouldPlay: true},
);
} catch (error) {
console.log('error inside play helper method', error.message)
}  
};
//pause
export const pause = async playbackObj => {
try {
// playbackObj.setRateAsync(rate = 2.0, shouldCorrectPitch = true, PitchCorrectionQuality= High);
return await playbackObj.setStatusAsync({
shouldPlay: false},
);
} catch (error) {
console.log('error inside pause helper method', error.message)
}  
};
//resume
export const resume = async playbackObj => {
try {
return await playbackObj.playAsync(
);
} catch (error) {
console.log('error inside pause resume method', error.message)
}  
};
//select next 
export const playNext = async (playbackObj, uri) => {
try {
await playbackObj.stopAsync()
await playbackObj.unloadAsync();
return await play(playbackObj, uri);
} catch (error) {
console.log('error inside playNext helper method')
}
}

我试过在this.state{audioFiles: []中包含'rate: 2.0'，permissionError: false，等等}但它不起作用。我也试过在第二个代码片段中做:await playbackObj.setRateAsync()。

有什么建议吗?

Answer 1

Nvm，我找到了解决方案。下面是我更新后的代码:

// play audio
// Import the react-native-sound module
import { PitchCorrectionQuality,shouldCorrectPitch, rate } from "expo-av/build/AV.types";
export const play = async (playbackObj, uri,) => {
try {
await playbackObj.loadAsync(
{uri}, 
{shouldPlay: true},
);
return await playbackObj.setStatusAsync({ rate: 0.9749090909 });
} catch (error) {
console.log('error inside play helper method', error.message)
}  
};
//pause
export const pause = async playbackObj => {
try {
return await playbackObj.setStatusAsync({
shouldPlay: false,
rate: 0.9749090909,
});
} catch (error) {
console.log('error inside pause helper method', error.message)
}  
};
//resume
export const resume = async playbackObj => {
try {
return await playbackObj.playAsync(
);
} catch (error) {
console.log('error inside pause resume method', error.message)
}  
};
//select next 
export const playNext = async (playbackObj, uri) => {
try {
await playbackObj.stopAsync()
await playbackObj.unloadAsync();
return await play(playbackObj, uri);
} catch (error) {
console.log('error inside playNext helper method')
}
}