How to embed Youtube live chat with url permanent?

The embed URL for a channel’s live stream is:

https://www.youtube.com/embed/live_stream?channel=CHANNEL_ID

and it works but if I want to embed near at it a YouTube live chat for current streaming the URL that I use for the embed is:

https://www.youtube.com/live_chat?v=VIDEOID&embed_domain=DOMAINURL 

The problem is this: for every new live stream the Video ID changes. So that the embedded code isn’t valid anymore and chat isn’t displayed for next streaming.I want a permanent URL live chat valid for all my YouTube streaming without change video id manually every time. How to resolve? Perhaps with a script in PHP or javascript that read current YouTube URL and replace video id in chat embed URL? thanks

Answer

You could get the video ID using PHP like this:

<?php

try {
    $videoId = getLiveVideoID('CHANNEL_ID');

    // Output the Chat URL
    echo "The Chat URL is https://www.youtube.com/live_chat?v=".$videoId;
} catch(Exception $e) {
    // Echo the generated error
    echo "ERROR: ".$e->getMessage();
}

// The method which finds the video ID
function getLiveVideoID($channelId)
{
    $videoId = null;

    // Fetch the livestream page
    if($data = file_get_contents('https://www.youtube.com/embed/live_stream?channel='.$channelId))
    {
        // Find the video ID in there
        if(preg_match('/'VIDEO_ID': "(.*?)"/', $data, $matches))
            $videoId = $matches[1];
        else
            throw new Exception('Couldn't find video ID');
    }
    else
        throw new Exception('Couldn't fetch data');

    return $videoId;
}