joelproko

Nevermind, the player will handle php scripts that redirect to the actual mp3 file just fine. You just have to urlencode stuff.
In my case

<script type="text/javascript">
    AudioPlayer.embed("audioplayer_1", {
        soundFile: "podcast/play.php<?php print(urlencode("?source=swf&file=".$_GET['audiofile'])); ?>",
        artists: "<?php print($_GET['audioautor']); ?>",
        titles: "<?php print($_GET['audiotitel']); ?>"
    });
</script>