title: how to convert raw mp3 binary into blob url and play it in audio tag
body: <p>What im doing is sending mp3 data through websockets as base64 strings and decoding it on browser side now what im trying to do is turn that raw data into a blob and play it in an audio tag but i dont know how can you help also decoding base64 strings is laggy is there a better way</p>
  
  <p><strong><em>JAVASCRIPT</em></strong></p>
  
  <pre><code>var Base64={_keyStr:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",encode:function(e){var t="";var n,r,i,s,o,u,a;var f=0;e=Base64._utf8_encode(e);while(f&lt;e.length){n=e.charCodeAt(f++);r=e.charCodeAt(f++);i=e.charCodeAt(f++);s=n&gt;&gt;2;o=(n&amp;3)&lt;&lt;4|r&gt;&gt;4;u=(r&amp;15)&lt;&lt;2|i&gt;&gt;6;a=i&amp;63;if(isNaN(r)){u=a=64}else if(isNaN(i)){a=64}t=t+this._keyStr.charAt(s)+this._keyStr.charAt(o)+this._keyStr.charAt(u)+this._keyStr.charAt(a)}return t},decode:function(e){var t="";var n,r,i;var s,o,u,a;var f=0;e=e.replace(/[^A-Za-z0-9+/=]/g,"");while(f&lt;e.length){s=this._keyStr.indexOf(e.charAt(f++));o=this._keyStr.indexOf(e.charAt(f++));u=this._keyStr.indexOf(e.charAt(f++));a=this._keyStr.indexOf(e.charAt(f++));n=s&lt;&lt;2|o&gt;&gt;4;r=(o&amp;15)&lt;&lt;4|u&gt;&gt;2;i=(u&amp;3)&lt;&lt;6|a;t=t+String.fromCharCode(n);if(u!=64){t=t+String.fromCharCode(r)}if(a!=64){t=t+String.fromCharCode(i)}}t=Base64._utf8_decode(t);return t},_utf8_encode:function(e){e=e.replace(/rn/g,"n");var t="";for(var n=0;n&lt;e.length;n++){var r=e.charCodeAt(n);if(r&lt;128){t+=String.fromCharCode(r)}else if(r&gt;127&amp;&amp;r&lt;2048){t+=String.fromCharCode(r&gt;&gt;6|192);t+=String.fromCharCode(r&amp;63|128)}else{t+=String.fromCharCode(r&gt;&gt;12|224);t+=String.fromCharCode(r&gt;&gt;6&amp;63|128);t+=String.fromCharCode(r&amp;63|128)}}return t},_utf8_decode:function(e){var t="";var n=0;var r=c1=c2=0;while(n&lt;e.length){r=e.charCodeAt(n);if(r&lt;128){t+=String.fromCharCode(r);n++}else if(r&gt;191&amp;&amp;r&lt;224){c2=e.charCodeAt(n+1);t+=String.fromCharCode((r&amp;31)&lt;&lt;6|c2&amp;63);n+=2}else{c2=e.charCodeAt(n+1);c3=e.charCodeAt(n+2);t+=String.fromCharCode((r&amp;15)&lt;&lt;12|(c2&amp;63)&lt;&lt;6|c3&amp;63);n+=3}}return t}}
  
      var AudioType = "audio/mp3";
      var protocol = "ws://";
      var host = "127.0.0.1";
      var port = 4446;
      var uri = protocol + host + ":" + port + "/"
      var ws = new WebSocket(uri);
      ws.onopen = function() {
          console.log("Connected");
          ws.send(JSON.stringify({"reqID3":1}));
          ws.send(JSON.stringify({"init":1}))
      }
      ws.onmessage = function(e){
          var js = JSON.parse(e.data);
          if (js.id3) {
              document.getElementById("bitrate").innerHTML = js.id3.bitrate;
              document.getElementById("length").innerHTML = js.id3.length;
              document.getElementById("title").innerHTML = js.id3.title;
          }
          if (js.buffer) {
              //console.log(js.buffer)
              var b = Base64.decode(js.buffer)
              console.log(b)
              var audio = document.getElementById("audio");
              audio.type = AudioType;
              audio.src = window.URL.createObjectURL(b);
  
  
          }
      }
      ws.onclose = function() {
          ws.close()
  </code></pre>