download all youtube videos of channels

downloadYoutubeChannel.php

<?php
/**
 * @author           FirePanther (http://suat.be)
 * @copyright        DevMe (http://devme.de)
 * @description      youtube.php: Download all videos of channels
 * @date             17/04/16
 * @dependencies     - youtube-dl (same location): https://yt-dl.org/downloads/2016.04.13/youtube-dl
 *                   - brew: AtomicParsley, coreutils (gtouch, gecho)
 */

date_default_timezone_set('Europe/Berlin');

define('API_KEY', '...');

$channels = [
	'Vsauce' => 'UC6nSFpj9HTCZ5t-N3Rm3-HA',
	'Kurzgesagt – In a Nutshell' => 'UCsXVk37bltHxD1rDPwtNM8Q',
	'Vsauce2' => 'UCqmugCqELzhIMNYnsjScXXw',
	'Vsauce3' => 'UCwmFOfFuvRPI112vR5DNnrA'
];

$pls = getChannelUploadsId(array_values($channels));
foreach ($pls as $pl) {
	$items = getPlaylistVideos($pl);
	$itemsNum = count($items);
	$i = 0;
	foreach ($items as $item) {
		if (!$i) echo 'Channel: '.$item['snippet']['channelTitle']."\n";
		echo (++$i)." of $itemsNum\n";
		echo $item['snippet']['title'].' ('.$item['snippet']['resourceId']['videoId'].'): ';
		echo dlVid(
			$item['snippet']['channelTitle'],
			$item['snippet']['title'],
			$item['snippet']['resourceId']['videoId'],
			$item['snippet']['publishedAt']
		)."\n";
	}
}

/**
 * Returns an array with the channel id as key and the uploads playlist id
 * as value.
 */
function getChannelUploadsId($cIds) {
	$a = @json_decode(fgc('https://www.googleapis.com/youtube/v3/channels?part=contentDetails&maxResults='.count($cIds).'&id='.implode(',', $cIds).'&key='.API_KEY), 1);
	if (isset($a['items']) && count($a['items'])) {
		$items = $a['items'];
		$uploads = [];
		foreach ($items as $item) {
			if (isset($item['contentDetails']['relatedPlaylists']['uploads'])) {
				$uploads[$item['id']] = $item['contentDetails']['relatedPlaylists']['uploads'];
			}
		}
		return $uploads;
	} else {
		return null;
	}
}

/**
 * Get all items (videos) of a playlist.
 */
function getPlaylistVideos($pl, $page = null) {
	$a = @json_decode(fgc('https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&'.($page ? 'pageToken='.$page.'&' : '').'playlistId='.$pl.'&key='.API_KEY), 1);
	if (isset($a['nextPageToken'])) {
		return array_merge($a['items'], getPlaylistVideos($pl, $a['nextPageToken']));
	} else {
		return $a['items'];
	}
}

/**
 * Downloads a single video.
 */
function dlVid($channel, $title, $v, $publishedAt) {
	if (!is_dir('cache')) mkdir('cache', 0777);
	if (is_file("cache/downloaded-$v")) return 'skip';
	
	$dir = "channels/$channel";
	if (!is_dir($dir)) mkdir($dir, 0777, 1);
	$filename = "$title.mp4";
	$filename = $dir.'/'.str_replace(" ⁄  ⁄ ", " ⁄ ⁄ ", str_replace("/", " ⁄ ", $filename));
	$filename = preg_replace_callback('~[^\w\s/!-.]+~', function($m) {
		return '\\x'.implode('\\x', str_split(bin2hex($m[0]), 2));
	}, $filename);
	$filename = escapeshellarg($filename);

	exec('./youtube-dl -q --no-call-home --recode-video mp4 --embed-subs '.
		' -f bestvideo[ext=mp4]+bestaudio[ext=m4a] '.
		'--embed-thumbnail --add-metadata -o '.
			'"'.__dir__.'/cache/dl-'.$v.'.%(ext)s" '.
		'--exec "/usr/local/bin/gtouch -a -m -d \"'.date('Y-m-d', strtotime($publishedAt)).'\" {} && mv {} \"\$(/usr/local/bin/gecho -e \"'.str_replace("'", '', $filename).'\")\"" "'.$v.'"');
	file_put_contents("cache/downloaded-$v", '');
	return 'ok';
}

/**
 * file_get_contents - cached
 */
function fgc($url, $cache = 1) {
	$cs = md5($url);
	if ($cache && is_file('cache/'.$cs) && filemtime('cache/'.$cs) < time()+3600*24) {
		return file_get_contents('cache/'.$cs);
	} else {
		$src = file_get_contents($url);
		if ($src && $cache) file_put_contents('cache/'.$cs, $src);
		return $src;
	}
}