Audio API 实现音频播放器

市面上实现音频播放器的库有很多，比如wavesurfer.js、howler.js等等，但是都不支持大音频文件处理，100多M的文件就有可能导致程序崩溃。总之和我目前的需求不太符合，所以打算自己实现一个音频播放器，这样不管什么需求在技术上都可控。下面我们简单介绍下wavesurferJs、和howlerJs的实现，然后再讲解如何利用audio API实现自定义语音播放器。

具体资源github下载

wavesurferJs

一开始选择wavesurferJs 主要是因为它的音频图功能。
效果如下：
在这里插入图片描述
是不是很漂亮 hh
下面是实现步骤：

初始化

this.playWavesurfer = WaveSurfer.create({
	container: '#waveform2',
	mediaType: 'audio',
	height: 43,
	scrollParent: false,
	hideScrollbar: true,
	waveColor: '#ed6c00',
	interact: true,
	progressColor: '#dd5e98',
	cursorColor: '#ddd5e9',
	interact: true,
	cursorWidth: 1,
	barHeight: 1,
	barWidth: 1,
	plugins: [
		WaveSurfer.microphone.create()
	]
});

动态加载音频地址

this.playWavesurfer.load(this.audioUrl);

设置加载loading和完毕后计算音频总时长

this.playWavesurfer.on('loading', (percent, xhr) => {
		this.audioLoadPercent = percent - 1;
	})
	this.playWavesurfer.on('ready', () => {
		this.audioLoading = false;
		const duration = this.playWavesurfer.getDuration();
		this.duration = this.formatTime(duration);
		this.currentTime = this.formatTime(0);
	})

播放中计算时长

this.playWavesurfer.on('audioprocess', function () {
	const duration = that.playWavesurfer.getDuration();
	const currentTime = that.playWavesurfer.getCurrentTime();
	that.currentTime = that.formatTime(currentTime);
	that.duration = that.formatTime(duration);
	if (that.currentTime === that.duration) {
		that.audioPlayingFlag = false;
	}
});

播放、暂停

this.playWavesurfer.playPause.bind(this.playWavesurfer)();

快进、快退

this.playWavesurfer.skip(15);
//this.playWavesurfer.skip(-15);

倍数播放

this.playWavesurfer.setPlaybackRate(value, true);

这样基本功能大概实现。

利用howlerJs实现

初始化、动态加载音频路径

this.howler = new Howl({
	src: [this.audioUrl]
});

加载完毕计算音频总时长

this.howler.on('load', () => {
	this.audioLoading = false;
	const duration = this.howler.duration();
	this.duration = this.formatTime(duration);
	this.currentTime = this.formatTime(0);
});

播放中获取当前时间

this.currentTime = this.formatTime(this.howler.seek());

播放完毕

this.howler.on('end', () => {
	this.audioPlayingFlag = false;
	this.siriWave2.stop();
	this.currentTime = "00:00:00";
	this.progressPercent = 0;
	cancelAnimationFrame(this.playTimer);
})

快进、快退

this.howler.seek(this.howler.seek() + 15);
//this.howler.seek(this.howler.seek() - 15);

设置倍数播放

this.howler.rate(value);

播放、暂停

this.howler.play();
// this.howler.pause();

手动定位播放时长

<div id="waveform2" ref="waveform2" @click="changProgress">
	<div class="bar" v-if="!audioLoading&&!audioPlayingFlag"></div>
	<div class="progress" :style="{width: `${progressPercent}`}"></div>
</div>

changProgress(e) {
	if (this.howler.playing()) {
		this.howler.seek((e.offsetX / this.$refs['waveform2'].offsetWidth)*this.howler.duration());
	}
},

这样基本功能大概实现。

利用audio API实现播放器

效果图：
在这里插入图片描述
动画库暂时用的 siriwave.js

先定义audio标签隐藏，可以js里面动态生成

<audio :src="audioUrl" style="display: none;" controls ref="audio"></audio>

this.audio = this.$refs['audio'];

获取音频url后动态加载需要load一下

this.audio.load();

音频加载完毕

this.audio.addEventListener("canplaythrough", () => {
	this.audioLoading = false;
	console.log('music ready');
}, false);

监听可以播放后计算音频时长

this.audio.addEventListener("canplay", this.showTime, false);

showTime() {
	if (!isNaN(this.audio.duration)) {
		this.duration = this.formatTime(this.audio.duration);
		this.currentTime = this.formatTime(this.audio.currentTime);
	}
},

播放中时间改变计算当前时间

this.audio.addEventListener("timeupdate", this.showTime, true);

监听播放事件

this.audio.addEventListener('play', () => {
	this.audioPlaying();
}, false);

播放完毕

this.audio.addEventListener('ended', () => {
	this.audioPlayingFlag = false;
	this.siriWave2.stop();
	this.currentTime = "00:00:00";
	this.progressPercent = 0;
	cancelAnimationFrame(this.playTimer);
}, false)

前进、后退

this.audio.currentTime += 15;
// this.audio.currentTime -= 15;

设置播放倍数

this.audio.playbackRate = value;

播放、暂停

this.audio.play();
// this.audio.pause();

音频定位

<div id="waveform2" ref="waveform2" @click="changProgress">
	<div class="bar" v-if="!audioLoading&&!audioPlayingFlag"></div>
	<div class="progress" :style="{width: `${progressPercent}`}"></div>
</div>

计算定位时长

changProgress(e) {
	// if (this.audioPlayingFlag) {
		this.audio.currentTime = (e.offsetX / this.$refs['waveform2'].offsetWidth)*this.audio.duration;
		this.progressPercent = ((this.audio.currentTime/this.audio.duration) * 100) + '%';
	// }
},

siri动画实现

this.siriWave = new SiriWave({
	container: that.$refs['waveform'],
		height: 43,
		cover: true,
		color: '#ed6c00',
		speed: 0.03,
		amplitude: 1,
		frequency: 6
	});

开启动画、停止动画

this.siriWave.start();
// this.siriWave.stop();

这样基本功能大概实现。即使加载再大音频文件也不会卡。

踩坑

在这里插入图片描述
这里遇到一个大坑就是 audio自带，音频播放定位功能，在外面浏览器和vscode主体代码里面都可以定位，偏偏我在vscode插件里面不可以定位，会自动归0。翻遍了文档在MDN上找到这样一段描述：
https://developer.mozilla.org/en-US/docs/Web/HTTP/Configuring_servers_for_Ogg_media#Handle_HTTP_1.1_byte_range_requests_correctly

Handle HTTP 1.1 byte range requests correctly
In order to support seeking and playing back regions of the media that aren’t yet downloaded, Gecko uses HTTP 1.1 byte-range requests to retrieve the media from the seek target position. In addition, Gecko uses byte-range requests to seek to the end of the media (assuming you serve the Content-Length header) in order to determine the duration of the media.
Your server should accept the Accept-Ranges: bytes HTTP header if it can accept byte-range requests. It must return 206: Partial content to all byte range requests; otherwise, browsers can’t be sure you actually support byte range requests.
Your server must also return 206: Partial Content for the request Range: bytes=0- as well.

经验证是和response header有关的。我通过对MP3资源set不同的response header来验证，结果如下(貌似segmentfault不支持markdown的表格，所以下面排版有点乱。)：
ie
Content-Type 必须，当我设为audio/mpeg时才能播放，设为application/octet-stream不能。
Content-Length必须。和Accept-Ranges无关。

chrome
Content-Type 无关，设为application/octet-stream可以播放。
Content-Length，Accept-Ranges必须都有才可更改 currentTime。

也就是说ie需要response header 有正确的Content-Type，Content-Length。
chrome需要头部有Content-Length和Accept-Ranges。

然后我想到 vscode插件系统使用了 Service Worker

const headers = {
		'Content-Type': entry.mime,
		'Content-Length': entry.data.byteLength.toString(),
		'Access-Control-Allow-Origin': '*',
	};

果然没有添加 Accept-Ranges字段

const headers = {
	'Content-Type': entry.mime,
	'Content-Length': entry.data.byteLength.toString(),
	'Access-Control-Allow-Origin': '*',
};

/**
 * @author lichangwei
 * @description 音频额外处理 否则无法调节进度
 * https://developer.mozilla.org/en-US/docs/Web/HTTP/Configuring_servers_for_Ogg_media#Handle_HTTP_1.1_byte_range_requests_correctly
 */

if (entry.mime === 'audio/mpeg') {
	headers['Accept-Ranges'] = 'bytes';
}