<html>
    <head>
        <script>
            function pageLoaded() {
                try {
                    window.webkit.messageHandlers.pictureInPictureChangeHandler.postMessage('load');
                } catch(e) { }
            }

            function play() {
                document.getElementById("audio").play();
            }

            function didStartPlaying() {
                try {
                    window.webkit.messageHandlers.pictureInPictureChangeHandler.postMessage('playing');
                } catch(e) { }
            }
        </script>
    </head>
    <body onload="pageLoaded()">
        <audio controls id="audio" src="silence-long.m4a" onplaying="didStartPlaying()" />
    </body>
</html>