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MIDI Input

MIDI Input:

This example requires Jazz-Plugin v.1.1 or later.

How it works

To watch this demo, you need a MIDI controller connected to your computer. MIDI messages will be displayed in the area above while you play your instrument.

Notice, that MIDI connection closes when the focus is lost and restores when it's back. - This trick allows sharing MIDI controller between multiple windows, pretty much like mouse or regular keyboard.

To see how it works when you switch windows, open another copy of this page in a .

Page source

<!DOCTYPE html>
<html>
<head>
<title>MIDI Input</title>

<style type="text/css">
.hidden {
 visibility:hidden;
 width:0px;
 height:0px;
 margin:0px;
 padding:0px;
 border-style:none;
 border-width:0px;
 max-width:0px;
 max-height:0px;
}
#msg {
 width:20em;
 height:24em;
 margin:.5em 0 .5em 0;
 padding:.5em;
 background-color:#eee;
 border:solid 1px #888;
 white-space:pre;
 font-family:Courier New, monospace;
 font-size:.75em;
 overflow:auto;
}
</style>
</head>

<body>
<h1>MIDI Input</h1>

<object id="Jazz1" classid="CLSID:1ACE1618-1C7D-4561-AEE1-34842AA85E90" class="hidden">
  <object id="Jazz2" type="audio/x-jazz" class="hidden">
<p style="visibility:visible;">This page requires <a href=http://jazz-soft.net>Jazz-Plugin</a> ...</p>
  </object>
</object>

<p>
MIDI Input:
<select id=midiIn onchange='changeMidi();'>
 <option value="">Not connected</option>
</select>
<div id=msg></div>
</p>

<script><!--
var Jazz;
var active_element;
var current_in;
var msg;
var sel;

//// Callback function
function midiProc(t,a,b,c){
 msg.innerHTML=msg.innerHTML+midiString(a,b,c)+"<br>";
 msg.scrollTop=msg.scrollHeight;
}
function midiString(a,b,c){
 var cmd=Math.floor(a/16);
 var note=['C','C#','D','Eb','E','F','F#','G','Ab','A','Bb','B'][b%12]+Math.floor(b/12);
 a=a.toString(16);
 b=(b<16?'0':'')+b.toString(16);
 c=(c<16?'0':'')+c.toString(16);
 var str=a+" "+b+" "+c+"    ";
 if(cmd==8){
  str+="Note Off   "+note;
 }
 else if(cmd==9){
  str+="Note On    "+note;
 }
 else if(cmd==10){
  str+="Aftertouch "+note;
 }
 else if(cmd==11){
  str+="Control    "+b;
 }
 else if(cmd==12){
  str+="Program    "+b;
 }
 else if(cmd==13){
  str+="Aftertouch";
 }
 else if(cmd==14){
  str+="Pitch Wheel";
 }
 return str;
}

//// Listbox
function changeMidi(){
 try{
  if(sel.selectedIndex){
   current_in=Jazz.MidiInOpen(sel.options[sel.selectedIndex].value,midiProc);
  } else {
   Jazz.MidiInClose(); current_in='';
  }
  for(var i=0;i<sel.length;i++){
   if(sel[i].value==current_in) sel[i].selected=1;
  }
 }
 catch(err){}
}

//// Connect/disconnect
function connectMidiIn(){
 try{
  var str=Jazz.MidiInOpen(current_in,midiProc);
  for(var i=0;i<sel.length;i++){
   if(sel[i].value==str) sel[i].selected=1;
  }
 }
 catch(err){}
}
function disconnectMidiIn(){
 try{
  Jazz.MidiInClose(); sel[0].selected=1;
 }
 catch(err){}
}
function onFocusIE(){
 active_element=document.activeElement;
 connectMidiIn();
}
function onBlurIE(){
 if(active_element!=document.activeElement){ active_element=document.activeElement; return;}
 disconnectMidiIn();
}

//// Initialize
Jazz=document.getElementById("Jazz1"); if(!Jazz || !Jazz.isJazz) Jazz = document.getElementById("Jazz2");
msg=document.getElementById("msg");
sel=document.getElementById("midiIn");
try{
 current_in=Jazz.MidiInOpen(0,midiProc);
 var list=Jazz.MidiInList();
 for(var i in list){
  sel[sel.options.length]=new Option(list[i],list[i],list[i]==current_in,list[i]==current_in);
 }
}
catch(err){}

if(navigator.appName=='Microsoft Internet Explorer'){ document.onfocusin=onFocusIE; document.onfocusout=onBlurIE;}
else{ window.onfocus=connectMidiIn; window.onblur=disconnectMidiIn;}
--></script>

</body>
</html>

See also