recorder-core
Version:
Recorder库: html5 js 录音 mp3 wav ogg webm amr g711a g711u 格式，支持pc和Android、iOS部分浏览器、Hybrid App（提供Android iOS App源码）、微信，提供ASR语音识别转文字 H5版语音通话聊天示例 DTMF编码解码
213 lines (195 loc) • 7.02 kB
JavaScript
/*
wav编码器+编码引擎
https://github.com/xiangyuecn/Recorder
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
浏览器支持情况
https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats
编码原理：给pcm数据加上一个44字节的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
注意：其他wav编码器可能不是44字节的头，要从任意wav文件中提取pcm数据，请参考：assets/runtime-codes/fragment.decode.wav.js
*/
(function(factory){
var rec=Object[Object["Recorder-Core-Alias"]||"Recorder-Core-Export"]; //Recorder挂载在Object下面
if(!rec) throw new Error("Must import recorder-core first");
factory(rec, rec.i18n.$T, rec.IsBrowser);
}(function(Recorder,$T,isBrowser){
;
Recorder.prototype.enc_wav={
stable:true,fast:true
,getTestMsg:function(){
return $T("gPSE::支持位数8位、16位（填在比特率里面），采样率取值无限制；此编码器仅在pcm数据前加了一个44字节的wav头，编码出来的16位wav文件去掉开头的44字节即可得到pcm（注：其他wav编码器可能不是44字节）");
}
};
var NormalizeSet=function(set){
var bS=set.bitRate,b=bS==8?8:16;
if(bS!=b) Recorder.CLog($T("wyw9::WAV Info: 不支持{1}位，已更新成{2}位",0,bS,b),3);
set.bitRate=b;
};
Recorder.prototype.wav=function(res,True,False){
var This=this,set=This.set;
NormalizeSet(set);
var size=res.length,sampleRate=set.sampleRate,bitRate=set.bitRate;
var dataLength=size*(bitRate/8);
//生成wav头
var header=Recorder.wav_header(1,1,sampleRate,bitRate,dataLength);
var offset=header.length;
var bytes=new Uint8Array(offset+dataLength);
bytes.set(header);
// 写入采样数据
if(bitRate==8) {
for(var i=0;i<size;i++) {
//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
var val=(res[i]>>8)+128;
bytes[offset++]=val;
};
}else{
bytes=new Int16Array(bytes.buffer);//长度一定是偶数
bytes.set(res,offset/2);
};
True(bytes.buffer,"audio/wav");
};
/**
根据参数生成wav文件头，返回Uint8Array（format=1时固定返回44字节，其他返回46字节）
format: 1 (raw pcm) 2 (ADPCM) 3 (IEEE Float) 6 (g711a) 7 (g711u)
numCh: 声道数
dataLength: wav中的音频数据二进制长度
**/
Recorder.wav_header=function(format,numCh,sampleRate,bitRate,dataLength){
//文件头 http://soundfile.sapp.org/doc/WaveFormat/ https://www.jianshu.com/p/63d7aa88582b https://github.com/mattdiamond/Recorderjs https://www.cnblogs.com/blqw/p/3782420.html https://www.cnblogs.com/xiaoqi/p/6993912.html
var extSize=format==1?0:2;
var buffer=new ArrayBuffer(44+extSize);
var data=new DataView(buffer);
var offset=0;
var writeString=function(str){
for (var i=0;i<str.length;i++,offset++) {
data.setUint8(offset,str.charCodeAt(i));
};
};
var write16=function(v){
data.setUint16(offset,v,true);
offset+=2;
};
var write32=function(v){
data.setUint32(offset,v,true);
offset+=4;
};
/* RIFF identifier */
writeString('RIFF');
/* RIFF chunk length */
write32(36+extSize+dataLength);
/* RIFF type */
writeString('WAVE');
/* format chunk identifier */
writeString('fmt ');
/* format chunk length */
write32(16+extSize);
/* audio format */
write16(format);
/* channel count */
write16(numCh);
/* sample rate */
write32(sampleRate);
/* byte rate (sample rate * block align) */
write32(sampleRate*(numCh*bitRate/8));// *1 声道
/* block align (channel count * bytes per sample) */
write16(numCh*bitRate/8);// *1 声道
/* bits per sample */
write16(bitRate);
if(format!=1){// ExtraParamSize 0
write16(0);
}
/* data chunk identifier */
writeString('data');
/* data chunk length */
write32(dataLength);
return new Uint8Array(buffer);
};
/**解码wav得到pcm，16位单声道
wavBlob: wav音频文件blob对象 或 ArrayBuffer，仅支持raw pcm格式的wav，单声道、双声道，8位、16位、24位、和32位浮点数
True(pcm,sampleRate,wavInfo) pcm为Int16Array，16位单声道，采样率为sampleRate
wavInfo:{
bitRate:8 16 24 32 //wav文件位数
numChannels:1 2 //声道数
dataPos:44 //数据开始位置，等于wav头长度
}
False(msg)
**/
Recorder.wav_decode=function(wavBlob,True,False){
var loadOk=function(aBuf){
//检测wav文件头
var wavView=new Uint8Array(aBuf);
var eq=function(p,s){
for(var i=0;i<s.length;i++){
if(wavView[p+i]!=s.charCodeAt(i)){
return false;
};
};
return true;
};
var pcm, sampleRate, bitRate, numCh, dataPos;
if(eq(0,"RIFF")&&eq(8,"WAVEfmt ")){
numCh=wavView[22]; var isRaw=wavView[20]==1, isFloat=wavView[20]==3;
if((isRaw||isFloat) && (numCh==1||numCh==2)){//1 raw pcm，3 IEEE Float
sampleRate=wavView[24]+(wavView[25]<<8)+(wavView[26]<<16)+(wavView[27]<<24);
bitRate=wavView[34]+(wavView[35]<<8);
//搜索data块的位置
dataPos=0; // 44 或有更多块
for(var i=12,iL=wavView.length-8;i<=iL;){
if(wavView[i]==100&&wavView[i+1]==97&&wavView[i+2]==116&&wavView[i+3]==97){//eq(i,"data")
dataPos=i+8;break;
}
i+=4;
i+=4+wavView[i]+(wavView[i+1]<<8)+(wavView[i+2]<<16)+(wavView[i+3]<<24);
}
if(dataPos){
var wLen=wavView.length-dataPos;
if(isRaw && bitRate==16){
pcm=new Int16Array(wavView.buffer.slice(dataPos));
}else if(isRaw && bitRate==8){ //8位转成16位
pcm=new Int16Array(wLen);
for(var j=dataPos,d=0,L=wavView.length;j<L;j++,d++){
var b=wavView[j];
pcm[d]=(b-128)<<8;
};
}else if(isRaw && bitRate==24){ //24bit pcm转成浮点数
pcm=new Int16Array(wLen/3);
for(var j=dataPos,d=0,L=wavView.length;j<L;){
var n=((wavView[j++] | (wavView[j++]<<8) | (wavView[j++]<<16))<<8)>>8;
n=n/16777216;
pcm[d++]=n<0?n*0x8000:n*0x7FFF; //浮点数转成16位
};
}else if(isFloat && bitRate==32){
var f32=new Float32Array(wavView.buffer.slice(dataPos,dataPos+(wLen-wLen%4)));
pcm=new Int16Array(f32.length);
for(var j=0,L=f32.length;j<L;j++){//floatTo16BitPCM
var s=Math.max(-1,Math.min(1,f32[j]));
s=s<0?s*0x8000:s*0x7FFF;
pcm[j]=s;
};
}
};
if(pcm && numCh==2){//双声道简单转单声道
var pcm1=new Int16Array(pcm.length/2);
for(var i=0,L=pcm1.length;i<L;i++){
pcm1[i]=(pcm[i*2]+pcm[i*2+1])/2;
}
pcm=pcm1;
};
};
};
if(!pcm){
False&&False($T("jXp3::非单或双声道wav raw pcm格式wav，不支持解码"));
return;
};
True&&True(pcm,sampleRate,{ bitRate:bitRate, numChannels:numCh, dataPos:dataPos });
};
if(wavBlob instanceof ArrayBuffer){
loadOk(wavBlob);
}else{
var reader=new FileReader();
reader.onloadend=function(){
loadOk(reader.result);
};
reader.readAsArrayBuffer(wavBlob);
};
};
}));