Генератор звуковых частот.

function createAudioMeter(audioContext, clipLevel, averaging, clipLag) 
{
 var processor = audioContext.createScriptProcessor(256); //512,fix
 processor.onaudioprocess = volumeAudioProcess;
 processor.clipping = false;
 processor.lastClip = 0;
 processor.volume = 0;
 processor.clipLevel = clipLevel || 0.98;
 processor.averaging = averaging || 0.95;
 processor.clipLag = clipLag || 750;
 
 // this will have no effect, since we don't copy the input to the output,
 // but works around a current Chrome bug.
processor.connect(audioContext.destination);
 
processor.checkClipping =function()
{
if (!this.clipping) return false;
if ((this.lastClip + this.clipLag) < window.performance.now())  this.clipping = false;
return this.clipping;
};
 
processor.shutdown =function(){ this.disconnect(); this.onaudioprocess = null;  };
return processor;
}
 
function volumeAudioProcess( event ) {
 var buf = event.inputBuffer.getChannelData(0);
 var bufLength = buf.length;
 var sum = 0;
 var x;
   // Do a root-mean-square on the samples: sum up the squares...
 for (var i=0; i<bufLength; i++) {
 x = buf[i];
 if (Math.abs(x)>=this.clipLevel) { this.clipping = true; this.lastClip = window.performance.now();  }
 sum += x * x;
 }
 
 
     var rms =  Math.sqrt(sum / bufLength);
     this.volume =  Math.max(rms, this.volume*this.averaging);
}
 
 
 
 
 
 
var audioContext = null;
var meter = null;
var canvasContext = null;
var audioCtxGen =null;
var oscillator =null;
 
var freqmin=50.0;
var freqmax=10000.0;
var currfreq= 50.0;
var fstep =50.0;
 
var WIDTH=1000;
var HEIGHT=300;
var timeoutID=null;
 
var delay=100;
var LevelIn=50;
var LevelOut=50;
 
var stepnum=0;
var dBmode=0; 
var streammode=0;
 
 
function  SetLevelIn()
{
LevelIn=document.getElementById("LevelInput").value;
document.getElementById("LevelIn1").innerHTML =LevelIn;
}
 
/*
function  SetLevelOut()
{
LevelOut=document.getElementById("LevelOutput").value;
document.getElementById("LevelOut1").innerHTML =LevelOut;
}
*/
 
 function UpdateLabels()
{
 document.getElementById("minfreq").innerHTML =freqmin;
 document.getElementById("maxfreq").innerHTML =freqmax;
 document.getElementById("delay1").innerHTML =delay;
 document.getElementById("step1").innerHTML =fstep;
}
window.onload = function Init() {UpdateLabels(); }
  
function OnChangeFmin(){freqmin=parseFloat(document.getElementById("FminIn").value);UpdateLabels();}
function OnChangeFmax(){ freqmax =parseFloat(document.getElementById("FmaxIn").value); UpdateLabels(); }
function OnChangeDelay(){ delay =parseFloat(document.getElementById("DelayIn").value) ; UpdateLabels(); }
function OnChangeStep(){ fstep =parseFloat(document.getElementById("StepIn").value) ;UpdateLabels(); }
 
 
//window.onload = functionOnClick() 
function didntGetStream() { alert('Stream generation failed.');  }
 
 
 
function CreateStream()
{
    window.AudioContext = window.AudioContext || window.webkitAudioContext; 
    audioContext = new AudioContext();
    try {
        navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia;
        navigator.getUserMedia(
        {
            "audio": {
                "mandatory": {
                    "googEchoCancellation": "false",
                    "googAutoGainControl": "false",
                    "googNoiseSuppression": "false",
                    "googHighpassFilter": "false"
                },
                "optional": []
            },
        }, gotStream, didntGetStream);
  } catch (e) { alert('getUserMedia threw exception :' + e);  }
}
 
 
var mediaStreamSource = null;
 /*
function CreateGainFun( )
{
var gainNode = null;
 var AudioContext = window.AudioContext || window.webkitAudioContext;
var audioCtx = new AudioContext();
 
var myAudio = document.querySelector('audio');
 gainNode =audioCtx.createGain();
 gainNode.gain.setValueAtTime(0, audioCtx.currentTime);
 source.connect(gainNode);
 gainNode.connect(audioCtx.destination);
 gainNode.gain.linearRampToValueAtTime(0.5, audioCtx.currentTime );
}
 
*/
 
function CreateOsc(  )
{
audioCtxGen = new (window.AudioContext || window.webkitAudioContext)();
oscillator = audioCtxGen.createOscillator();
oscillator.type = 'sine';
oscillator.frequency.setValueAtTime(currfreq, audioCtxGen.currentTime); // value in hertz
oscillator.connect(audioCtxGen.destination);
oscillator.start();
}
 
 
function CreateInputLevelMeter(stream)
{
    mediaStreamSource = audioContext.createMediaStreamSource(stream);
    meter = createAudioMeter(audioContext);
    mediaStreamSource.connect(meter);
}
 
 var Coeffs= new Float64Array(2048);
 Coeffs.fill(1);
  
 
function GetLevel(){    guard_delay(); return (meter.volume *1.41)  *(LevelIn*0.01); }
 
 
 
function GetValue(Ldata , nstep1, modedB, mode1  )
{
     
var datadBIn=20*Math.log10(Ldata );
var dataIn=Ldata ;
if (mode1==1) {  datadBIn+= Coeffs [nstep1] ; dataIn*= Coeffs[ nstep1] ; } 
      document.getElementById("Vinp1").innerHTML =dataIn.toExponential(4); 
      document.getElementById("Vinp2").innerHTML =datadBIn.toFixed(1); 
 if (modedB==1)   { return datadBIn} else { return dataIn ; }
    return dataIn ;  
}
 
function CreateNormCoefsArray(stepnum,  mode, indata )
{  
var coeftmp=1;
var i=stepnum;
 
if (mode==0){ coeftmp=1/(indata+(1e-12));   } //obtain coeff.   for     Level*Coeffs=1return; 
if (mode==1){ coeftmp=(-indata);  } //obtain coeff.   for     Level+Coeffs =return;
Coeffs[i]=coeftmp;
 
}
 
 function dsleep(milliseconds) {
 var start = new Date().getTime();
 for (var i = 0; i < 1e7; i++) { if ((new Date().getTime() - start) > milliseconds) {   break; } }
}
 
 function guard_delay(){ dsleep(delay); }
 
function UpdateFreqValue()
{   
document.getElementById("curfreq1").innerHTML =currfreq.toFixed(2);  
oscillator.frequency.value=currfreq; 
//oscillator.frequency.setValueAtTime(currfreq, audioCtxGen.currentTime); 
// oscillator.frequency.linearRampToValueAtTime(currfreq, audioCtxGen.currentTime);
}
 
 
 
function SetPoint(numstep,  V ,  num)
{
var dxPos=2;
var xPos=numstep*dxPos;
var yPos ;
if (dBmode==0) { yPos=HEIGHT*(1-V); } else  { yPos=HEIGHT*(1-0.7)-  V *(HEIGHT/120);  }
 
    canvasContext.beginPath();
       
      canvasContext.moveTo( xPos, HEIGHT);
     canvasContext.lineTo( xPos, yPos);  //fix
       // canvasContext.moveTo( xPos, yPos);
       //canvasContext.lineTo( xPos+1, yPos);  //fix
    if (meter.checkClipping()){  canvasContext.strokeStyle ="red"; } // тёмно-синий цвет
    else  { canvasContext.strokeStyle ="green"; }
 canvasContext.lineWidth =dxPos;
  canvasContext.stroke();
}
 
 
 
 function NormLoop(  ) 
{
 var tmpdata;
 if (currfreq<=freqmax)
{
   document.getElementById("nstep").innerHTML =stepnum ;
   UpdateFreqValue(); 
    tmpdata=GetLevel();   
   
   CreateNormCoefsArray(stepnum,   dBmode  , GetValue(tmpdata,  stepnum, dBmode, 0 ) );
 
   if  ( document.getElementById("NormCoefs").checked )  { tmpdata =GetValue(tmpdata, stepnum , dBmode , 1 ) ; } else 
  {  tmpdata =GetValue(tmpdata, stepnum , dBmode , 0 ) ; }
 
    SetPoint( stepnum,  tmpdata);
    currfreq +=fstep;   
    stepnum++;
  }
  else{ StopOnClick();  }
}
 
 
 function drawLoop(  ) 
{
 var tmpdata;
 if (currfreq<=freqmax)
{
    document.getElementById("nstep").innerHTML =stepnum ;
     UpdateFreqValue(); 
     tmpdata=GetLevel();  
 
   if  ( document.getElementById("NormCoefs").checked )  { tmpdata =GetValue(tmpdata, stepnum , dBmode , 1 ) ;
} else 
 
 {  tmpdata =GetValue(tmpdata, stepnum , dBmode , 0 ) ; }
     SetPoint( stepnum,  tmpdata);
    currfreq  += fstep;   
    stepnum++;
}
else{  StopOnClick(); }
}
 
 
 function drawLoop1(  ) 
{
    var tmpdata;
 
     document.getElementById("nstep").innerHTML =0 ;
     UpdateFreqValue(); 
     tmpdata=(meter.volume *1.41)*(LevelIn*0.01);  
     tmpdata =GetValue(tmpdata, 0 , 0 , 0 ) ;
     var yPos1=HEIGHT*(1-tmpdata);
 
       canvasContext.clearRect(0,0,WIDTH, HEIGHT);
       canvasContext.beginPath();
       canvasContext.moveTo( 100, HEIGHT);
       canvasContext.lineTo(100, yPos1);  //fix
    
       if (meter.checkClipping()){  canvasContext.strokeStyle ="red"; } // тёмно-синий цвет
       else  { canvasContext.strokeStyle ="green"; }
  canvasContext.lineWidth =20;
  canvasContext.stroke();
 
}
 
 
function GetNumberofPoints(){ return 1+Math.ceil ((freqmax-freqmin)/fstep); }
function gotStream(stream) 
{
    CreateInputLevelMeter(stream); 
    CreateOsc( ); 
    Coeffs.length=GetNumberofPoints();
if (streammode==0){   timeoutID=setInterval( drawLoop , 50);   }
if (streammode==1){     if (dBmode==1) { Coeffs.fill(0) ; } else { Coeffs.fill(1) ; }    timeoutID=setInterval( NormLoop , 50 );  } 
if (streammode==2){     timeoutID=setInterval(  drawLoop1  , 50 );  } 
 
 } 
 
function StopOnClick()
{
clearInterval( timeoutID);
timeoutID=null  ;
oscillator.stop();
oscillator.disconnect();
currfreq=freqmin;
 
 meter =null;
mediaStreamSource = null;
audioCtxGen =null;
 audioContext =null;
stepnum=0;
if(streammode==2) canvasContext.clearRect(0,0,WIDTH, HEIGHT);
}
 
 
function ClearOnClick(){ StopOnClick(); canvasContext.clearRect(0,0,WIDTH, HEIGHT);}
function ClearCoefsOnClick(){ Coeffs.length=GetNumberofPoints() ; if (dBmode==1) { Coeffs.fill(0) ; } else { Coeffs.fill(1) ; } }
 
 
function RunOnClick() 
{
(document.getElementById("LogMode").checked==true)  ? dBmode=1 : dBmode=0; 
if (dBmode==1)  { document.getElementById("currmode").innerHTML ="Log. Mode " ;}
if (dBmode==0)  { document.getElementById("currmode").innerHTML ="Lin.  Mode " ; }
currfreq=freqmin;
streammode=0;
UpdateLabels();
 canvasContext = document.getElementById( "meter" ).getContext("2d");
 canvasContext.clearRect(0,0,WIDTH, HEIGHT);
CreateStream();
}
 
function NormOnClick() 
{
(document.getElementById("LogMode").checked==true)  ? dBmode=1 : dBmode=0; 
if (dBmode==1)  { document.getElementById("currmode").innerHTML ="Log. Mode " ;}
if (dBmode==0)  { document.getElementById("currmode").innerHTML ="Lin.  Mode " ; }
currfreq=freqmin;
streammode=1;
UpdateLabels();
 canvasContext = document.getElementById( "meter" ).getContext("2d");
 canvasContext.clearRect(0,0,WIDTH, HEIGHT);
 
CreateStream();
 
}
function LevelOnClick(){
 
currfreq=parseFloat(prompt('Input frequency, Hz ?', 1000.0) );
 streammode=2;
UpdateLabels();
document.getElementById("currmode").innerHTML ="Log. Mode ";
 canvasContext = document.getElementById( "meter" ).getContext("2d");
 canvasContext.clearRect(0,0,WIDTH, HEIGHT);
CreateStream();
 
}