96 lines
2.6 KiB
JavaScript
96 lines
2.6 KiB
JavaScript
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/*
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pcm编码器+编码引擎
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https://github.com/xiangyuecn/Recorder
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编码原理：本编码器输出的pcm格式数据其实就是Recorder中的buffers原始数据（经过了重新采样），16位时为LE小端模式（Little Endian），并未经过任何编码处理
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编码的代码和wav.js区别不大，pcm加上一个44字节wav头即成wav文件；所以要播放pcm就很简单了，直接转成wav文件来播放，已提供转换函数 Recorder.pcm2wav
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*/
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(function(){
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"use strict";
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Recorder.prototype.enc_pcm={
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stable:true
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,testmsg:"pcm为未封装的原始音频数据，pcm数据文件无法直接播放；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.pcm=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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,bitRate=set.bitRate==8?8:16;
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var buffer=new ArrayBuffer(size*(bitRate/8));
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var data=new DataView(buffer);
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var offset=0;
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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/pcm"}));
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};
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/**pcm直接转码成wav，可以直接用来播放；需同时引入wav.js
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data: {
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sampleRate:16000 pcm的采样率
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bitRate:16 pcm的位数 取值：8 或 16
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blob:blob对象
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}
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data如果直接提供的blob将默认使用16位16khz的配置，仅用于测试
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True(wavBlob,duration)
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False(msg)
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**/
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Recorder.pcm2wav=function(data,True,False){
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if(data.slice && data.type!=null){//Blob 测试用
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data={blob:data};
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};
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var sampleRate=data.sampleRate||16000,bitRate=data.bitRate||16;
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if(!data.sampleRate || !data.bitRate){
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console.warn("pcm2wav必须提供sampleRate和bitRate");
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};
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if(!Recorder.prototype.wav){
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False("pcm2wav必须先加载wav编码器wav.js");
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return;
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};
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var reader=new FileReader();
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reader.onloadend=function(){
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var pcm;
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if(bitRate==8){
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//8位转成16位
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var u8arr=new Uint8Array(reader.result);
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pcm=new Int16Array(u8arr.length);
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for(var j=0;j<u8arr.length;j++){
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pcm[j]=(u8arr[j]-128)<<8;
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};
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}else{
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pcm=new Int16Array(reader.result);
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};
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Recorder({
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type:"wav"
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,sampleRate:sampleRate
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,bitRate:bitRate
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}).mock(pcm,sampleRate).stop(function(wavBlob,duration){
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True(wavBlob,duration);
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},False);
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};
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reader.readAsArrayBuffer(data.blob);
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};
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})();
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