PHP: Check from Twitch.tv APIv3 if channel is live

twitch_check.php

<?php

/**
 *  Use Twitch.tv API v3 to check if the specified channel has stream going on
 *
 *  @author                     Niko Heikkilä, 2014
 *  @param STRING $channel      Representing the channel/account name
 *  @return BOOL                TRUE if online, FALSE if offline
 */
 
function is_channel_live( $channel )
{
    $request = json_decode( @file_get_contents( 'https://api.twitch.tv/kraken/streams/' . $channel ) );
    return ( ! is_null( $request->stream ) ) ? TRUE : FALSE;
}

?>

To add the image create a check, like
if(is_channel_live("pewdiepie")){
echo "";
}else{
echo "";
}

And no, That is a method which you would call using $channel as a parameter. to get a true or false response you would just call
is_channel_live("channelname");
and that would return TRUE or FALSE

@SrJoosh and @shadowcoinx:

Yep, I'd modify this script to be checked via AJAX (it just needs to echo back something useful for XHR request) and then add the desired elements with Javascript (or jQuery, if that's your thing) to the page's HTML. There could be a interval/repeat function or a refresh button that would launch the request.