gistfile1.php

<?php
$json = <<<JSON
{
	"kind": "youtube#searchListResponse",
	"etag": "\"I_8xdZu766_FSaexEaDXTIfEWc0/hys1HflQr8XiiYpydVnkJA-oudA\"",
	"regionCode": "DE",
	"pageInfo": {
		"totalResults": 1,
		"resultsPerPage": 5
	},
	"items": [{
		"kind": "youtube#searchResult",
		"etag": "\"I_8xdZu766_FSaexEaDXTIfEWc0/VriB3fWVmI-YytLihGJXqyohdgY\"",
		"id": {
			"kind": "youtube#video",
			"videoId": "dnKMDe-i6HA"
		},
		"snippet": {
			"publishedAt": "2015-08-26T17:35:58.000Z",
			"channelId": "UCN32fF7zoJxEUBKonRiIIRw",
			"title": "heut kein Frühstück, muss Credits verdienen",
			"description": "Lockeres zocken zum wach werden und bissel farmen für ein neues Raumschiff.",
			"thumbnails": {
				"default": {
					"url": "https://i.ytimg.com/vi/dnKMDe-i6HA/default_live.jpg",
					"width": 120,
					"height": 90
				},
				"medium": {
					"url": "https://i.ytimg.com/vi/dnKMDe-i6HA/mqdefault_live.jpg",
					"width": 320,
					"height": 180
				},
				"high": {
					"url": "https://i.ytimg.com/vi/dnKMDe-i6HA/hqdefault_live.jpg",
					"width": 480,
					"height": 360
				}
			},
			"channelTitle": "KompetenzTeam",
			"liveBroadcastContent": "live"
		}
	}]
}
JSON;

/*$request = json_decode(@file_get_contents('https://www.googleapis.com/youtube/v3/search?part=snippet&channelId=UCN32fF7zoJxEUBKonRiIIRw&type=video&eventType=live&key=AIzaSyDN4O5RQZf-o2UkgNNRCcyxJPZETcNJeCo'), true);

$key1 = 'liveBroadcastContent';
$val1 = 'live';

function find_key_value($array, $key, $val)
{
    foreach ($array as $item) {
        if (is_array($item) && find_key_value($item, $key, $val)) return true;
        if (isset($item[$key]) && $item[$key] == $val) return true;
    }

    return false;
}

;

$result = find_key_value($request, $key1, $val1);

if ($result = "1") {
    echo '<img src="images/template_related/youtube_is_LIVE_light.png" />';
} else {
    echo '<img src="images/template_related/youtube_not_LIVE_light.png" />';
}*/

$response = json_decode($json, true);

//
$channel = array_filter($response['items'], function($n) {
    return $n['snippet']['liveBroadcastContent'] == 'live';
});

echo sprintf('<img src="images/template_related/youtoube_%s_LIVE_light.png" />', count($channel) ? 'is' : 'not');