Can I mute the audio of a youtube video when configured to autoplay?

Looks like it can be done from the embed code. Example:

<iframe width="260" height="195" src="//www.youtube.com/embed/h3P1OR9gg2Y?rel=0&autoplay=1" frameborder="0" allowfullscreen volume="0"></iframe>

Ref: https://productforums.google.com/forum/#!topic/youtube/XS5_P_9OXCo

Thanks :) Please, check out the above URL. I’ve fixed the code above too. It’s now an example.

Thanks.

Unfortunately, I don’t see volume on the list of parameters here:
https://developers.google.com/youtube/player_parameters?hl=en

Hi everyone :)

Unfortunately, this task isn’t currently possible using standard YouTube query parameters. However, we can achieve by inserting the following into the Text tab of the WordPress editor OR into a Text widget or SiteOrigin Editor widget (Text tab):

<!-- 1. The <iframe> (and video player) will replace this <div> tag. -->
<div id="player"></div>
<script>
      // 2. This code loads the IFrame Player API code asynchronously.
      var tag = document.createElement('script');
      tag.src = "https://www.youtube.com/iframe_api";
      var firstScriptTag = document.getElementsByTagName('script')[0];
      firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);
      // 3. This function creates an <iframe> (and YouTube player)
      //    after the API code downloads.
      var player;
      function onYouTubeIframeAPIReady() {
        player = new YT.Player('player', {
          height: '315',
          width: '560',
          videoId: 'ilrvQyRF3_g',
          events: {
            'onReady': onPlayerReady,
            'onStateChange': onPlayerStateChange
          }
        });
      }
      // 4. The API will call this function when the video player is ready.
      function onPlayerReady(event) {
           event.target.setVolume(0);
       event.target.playVideo();
      }
      // 5. The API calls this function when the player's state changes.
      //    The function indicates that when playing a video (state=1),
      //    the player should play for six seconds and then stop.
      var done = false;
      function onPlayerStateChange(event) {
        if (event.data == YT.PlayerState.PLAYING && !done) {
    //      setTimeout(stopVideo, 6000);
                  done = true;
        }
           event.target.setVolume(0);
      }
</script>

The following values in the above example should be located and replaced with your own unique values:

height: '315',
width: '560',

Replace the height value and the width value. To get standard sizes, go to your YouTube video and click on ShareEmbedShow MoreVideo Size. Only replace 315 and 560 in the code snippet.

The next line is the video ID:

videoId: 'ilrvQyRF3_g',

The video ID can be easily located in the video URL on YouTube. For example: https://www.youtube.com/watch?v=ilrvQyRF3_g. The ID is:

v=ilrvQyRF3_g

Only replace the ID, leaving the inverted commas in place.

Credit: https://productforums.google.com/forum/#!topic/youtube/XS5_P_9OXCo