ustream_check.php

<?php
// Pull from the db the list of channel names
$channels = array('music-for-japan-2011', '6819043', 'chelupa');

function live_channels($channels)
{
  $live_channels = array();
  $channels_string = implode(';', $channels);
  $url = 'http://api.ustream.tv/php/channel/'.$channels_string.'/getinfo';
  $ch = curl_init();
  $timeout = 5;
  curl_setopt($ch,CURLOPT_URL,$url);
  curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
  curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,$timeout);
  $response = curl_exec($ch);
  curl_close($ch);
  $resultsArray = unserialize($response);
  foreach ($resultsArray['results'] as $result) {
    if($result['result']['status'] == 'live') {
      $live_channels[] = $result['uid'];
      //print_r($result);
    }
  }
  return $live_channels;
}

while (1) {
  foreach (live_channels($channels) as $live_channel) {
    echo "$live_channel is live!\n";
    // Mysql query here? set a boolean value on the channels that are live
  }
  sleep(20); // Make the request only every 20sec
}

?>