# 用浏览器轻松录制音频、视频—— MediaRecorder API

requestMediaAccess () {
	//获取用户媒体权限，视频的话参数{audio: true, video: true}
    navigator.mediaDevices.getUserMedia({audio: true}).then(stream => {
    	//创建媒体录制对象
        this.recorder = new window.MediaRecorder(stream);
        this.bindEvents();
    }, error => {
        alert('出错，请确保已允许浏览器获取录音权限');
    });
}

bindEvents () {
    this.recorder.ondataavailable = this.getRecordingData;
    this.recorder.onstop = this.saveRecordingData;
},

getRecordingData (e) {
	//录制的数据
    this.chunks.push(e.data);
},

//保存音频数据
saveRecordingData  () {
    let blob = new Blob(this.chunks, { 'type' : 'audio/ogg; codecs=opus' }),
        audioStream = URL.createObjectURL(blob),
        //估算时长
        duration = parseInt(blob.size / 6600);
    if(duration <= 0) {
        alert('说话时间太短');
        return;
    }
    if(duration > 60) {
        duration = 60;
    }
    this.chunkList.push({duration: duration, stream: audioStream});
    this.chunks = [];
},

//视频的话：保存视频数据
saveRecordingData  () {
    let blob = new Blob(this.chunks, { 'type' : 'video/webm' }),
        videoStream = URL.createObjectURL(blob);
    this.chunkList.push({stream: videoStream});

    this.onCapture(this.index);        

    this.chunks = [];
},

//视频：获取视频截图
onCapture (index) {
    let item = this.chunkList[index];
    this.ctx.drawImage(this.video, 0, 0, this.canvas.width, this.canvas.height);
    this.canvas.toBlob((blob) => {
        let src = URL.createObjectURL(blob);
        this.$set(item, 'poster', src);
    });
    //索引后移
    this.index ++;

    //隐藏video
    this.showVideo(false);
    this.video.srcObject = null;
}