function swfplaylist_calculateLength(playlistItems)
{
  var totalLength = 0;
  for (var i = 0; i < playlistItems.length; ++i)
  {
    totalLength += playlistItems[i].duration_virtual - playlistItems[i].start;
  }

  return totalLength;
}

function swfplaylist_secondsToCoordinates(playlistItems, seconds)
{
  var currentStart = 0;
  for (var i = 0; i < playlistItems.length; ++i)
  {
    var nextStart = currentStart + playlistItems[i].duration_virtual - playlistItems[i].start;
    if (seconds < nextStart)
    {
      return { index : i, offset : seconds - currentStart };
    }

    currentStart = nextStart;
  }

  return { index : 0, offset : 0 };
}