Audio file not playing

Looking at this problem some more, I've isolated where I think the problem is occurring. In the file mediafield_display.module where the 1pixelout player is called, it's generating an incorrect URL for the audio file (below).

function theme_mediafield_display_1pixelout($file, $item, $field) {
  global $base_url;

  $options = array();
  $options['soundFile'] = check_url($base_url .'/'. $file['filepath']);
  $url = $base_url .'/'. drupal_get_path('module', 'mediafield_display') .'/players/1pixelout.swf';

  $flashvars = array();
  foreach ($options as $key => $val) {
    $flashvars[] = rawurlencode($key) .'='. rawurlencode($val);
  }
  $flashvars = implode('&', $flashvars);

$output = <<<EOT
<object type="application/x-shockwave-flash" data="$url" width="290" height="24" >
  <param name="movie" value="$url" />
  <param name="wmode" value="transparent" />
  <param name="menu" value="false" />
  <param name="quality" value="high" />
  <param name="FlashVars" value="$flashvars" />
</object>
EOT;

  return $output;
}

I believe this may be similar to http://drupal.org/node/179439 where the solution was to use str_replace (below).

function theme_audio_1pixelout_node_player($node, $options = array()) {
  // make sure it's compatible with the flash player
  if (!audio_is_flash_playable($node)) {
    return NULL;
  }

  $options['soundFile'] = check_url($node->url_play);
  $url = base_path() . drupal_get_path('module', 'audio') .'/players/1pixelout.swf';
  $flashvars = audio_query_string_encode($options);

  // '#' seems to encode as %2523, reverse this, using a more robust hex prefix..
  $flashvars = str_replace('%2523', '0x', $flashvars);

  // '/' seems to encode as %252F, reverse this back to '/'
  $flashvars = str_replace('%252F', '/', $flashvars);
$output = <<<EOT
<object type="application/x-shockwave-flash" data="$url" width="290" height="24" >
  <param name="movie" value="$url" />
  <param name="wmode" value="transparent" />
  <param name="menu" value="false" />
  <param name="quality" value="high" />
  <param name="FlashVars" value="$flashvars" />
  <embed src="$url" flashvars="$flashvars" width="290" height="24" />
</object>
EOT;

  return $output;
}

However, I'm unable to tweak mediafield_display.module to generate the proper URL for the audio. Am I barking up the right tree?