mirror of
https://github.com/babysor/MockingBird.git
synced 2024-03-22 13:11:31 +08:00
86 lines
2.5 KiB
JavaScript
86 lines
2.5 KiB
JavaScript
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/*
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wav编码器+编码引擎
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https://github.com/xiangyuecn/Recorder
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当然最佳推荐使用mp3、wav格式，代码也是优先照顾这两种格式
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浏览器支持情况
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https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats
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编码原理：给pcm数据加上一个44直接的wav头即成wav文件；pcm数据就是Recorder中的buffers原始数据（重新采样），16位时为LE小端模式（Little Endian），实质上是未经过任何编码处理
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*/
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(function(){
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"use strict";
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Recorder.prototype.enc_wav={
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stable:true
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,testmsg:"支持位数8位、16位（填在比特率里面），采样率取值无限制"
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};
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Recorder.prototype.wav=function(res,True,False){
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var This=this,set=This.set
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,size=res.length
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,sampleRate=set.sampleRate
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,bitRate=set.bitRate==8?8:16;
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//编码数据 https://github.com/mattdiamond/Recorderjs https://www.cnblogs.com/blqw/p/3782420.html https://www.cnblogs.com/xiaoqi/p/6993912.html
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var dataLength=size*(bitRate/8);
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var buffer=new ArrayBuffer(44+dataLength);
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var data=new DataView(buffer);
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var offset=0;
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var writeString=function(str){
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for (var i=0;i<str.length;i++,offset++) {
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data.setUint8(offset,str.charCodeAt(i));
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};
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};
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var write16=function(v){
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data.setUint16(offset,v,true);
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offset+=2;
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};
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var write32=function(v){
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data.setUint32(offset,v,true);
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offset+=4;
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};
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/* RIFF identifier */
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writeString('RIFF');
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/* RIFF chunk length */
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write32(36+dataLength);
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/* RIFF type */
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writeString('WAVE');
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/* format chunk identifier */
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writeString('fmt ');
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/* format chunk length */
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write32(16);
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/* sample format (raw) */
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write16(1);
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/* channel count */
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write16(1);
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/* sample rate */
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write32(sampleRate);
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/* byte rate (sample rate * block align) */
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write32(sampleRate*(bitRate/8));
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/* block align (channel count * bytes per sample) */
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write16(bitRate/8);
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/* bits per sample */
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write16(bitRate);
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/* data chunk identifier */
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writeString('data');
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/* data chunk length */
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write32(dataLength);
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// 写入采样数据
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if(bitRate==8) {
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for(var i=0;i<size;i++,offset++) {
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//16转8据说是雷霄骅的 https://blog.csdn.net/sevennight1989/article/details/85376149 细节比blqw的按比例的算法清晰点，虽然都有明显杂音
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var val=(res[i]>>8)+128;
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data.setInt8(offset,val,true);
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};
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}else{
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for (var i=0;i<size;i++,offset+=2){
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data.setInt16(offset,res[i],true);
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};
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};
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True(new Blob([data.buffer],{type:"audio/wav"}));
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}
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})();
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