title: Upload audio blob after conversion from wav to mp3
body: <pre><code>
  function init() {
      var cfg = {};
      audio = new Recorder(cfg);
  }
  
  function toggle( btn ){ // audio &amp;&amp; audio.record();
  
      if(audio instanceof Recorder){
  
  
          var btnLabel = btn.firstChild.nodeValue;
  
          if( btnLabel === 'Record' ){
              audio.record();
          }else{
             audio.stop();
             createPreview( 'recordings' );
             audio.clear();
          }
  
          btn.firstChild.nodeValue = (btnLabel === 'Record') ? 'Stop' : 'Record';
          btn.setAttribute('class', (btn.getAttribute('class') === 'btn btn-primary') ? 'btn btn-danger' : 'btn btn-primary');
  
      } else {
          init();
          toggle( btn );
      }
  
  }
  
  function createPreview( containerId ) {
      // audio &amp;&amp; audio.exportWAV( function(blob) {
  
      var targetContainer = document.getElementById( containerId );
      var timestamp = new Date().getTime();
      var filename = 'recording_'+ timestamp;
      var div = document.createElement('div');
  
      var linkMP3 = document.createElement('a');
          linkMP3.setAttribute('id', 'MP3-'+ timestamp);
  
      var iconMP3 = document.createElement('img');
          iconMP3.setAttribute('src', 'images/i-mp3.jpeg');
      
      var linkWAV = document.createElement('a');
          linkWAV.setAttribute('id', 'WAV-'+ timestamp);
  
      var iconWAV = document.createElement('img');
          iconWAV.setAttribute('src', 'images/i-wav.jpeg');
  
      var player = document.createElement('audio');
          player.setAttribute('id', 'PLAYER-'+ timestamp);
          player.controls = true;
      
      div.appendChild(player);
      div.appendChild(linkWAV);
      div.appendChild(linkMP3);
      targetContainer.appendChild(div);
      
      audio.export( function( mediaObj ) {
  
          if( mediaObj.blob.type == 'audio/mp3' ){
  
              var url = mediaObj.url;
              targetLink = document.getElementById( 'MP3-'+ timestamp );
              
              targetLink.href = url;
              targetLink.download = filename +'.mp3';
              targetLink.innerHTML = targetLink.download;
  
              saveAudio( url, filename );
            
          } else { // 'audio/wav'
  
              var url = URL.createObjectURL( mediaObj.blob );
              targetPlayer = document.getElementById( 'PLAYER-'+ timestamp );
              targetLink = document.getElementById( 'WAV-'+ timestamp );
              
              targetPlayer.src = url;
              targetLink.href = url;
              targetLink.download = filename +'.wav';
              targetLink.innerHTML = targetLink.download;
  
          }
      });
  }
  
  function saveAudio( url, filename ){
  
      var firebaseUrl = 'your_firebase_url';
  
      if(firebaseUrl !== 'your_firebase_url'){
          
          console.info('&gt;&gt; saving audio: url');
          console.log( url );
  
          ref = new Firebase( firebaseUrl );
          ref.set({
              filetype: 'audio/mp3',
              base64Str: url,
              filename: filename +'.mp3'
          });
      
      }else{
  
          console.warn('Audio not saved to firebase because firebaseUrl is undefined.');
  
      }
  }
  </code></pre>
  <p>I need to record audio in the browser (short clips, spoken voice, mono) and upload it in mp3 format. <a href="https://github.com/geirman/recorder-wav-mp3" rel="nofollow noreferrer">This by Chris Geirman</a> has almost everything that I need, except that instead of using firebase, I'd like to use jquery to upload audio blobs to a folder on my server. I'm fairly new to all of this, but I'm guessing that I need to replace the saveAudio() function with my own uploadAudio() jquery(?) function (something like <a href="https://stackoverflow.com/a/21746318/9185827">this</a>), which will link to a script in /upload.php. So far so good (?), but I can't figure out from Chris's script exactly what it is that I should be uploading / passing to /upload.php. I'm planning to implement the script <a href="https://www.ialf.edu/steve_b/speaking_test.php" rel="nofollow noreferrer">here</a>.</p>