带有 php 的 youtube 视频下载器

Question

我正在尝试使用 php 制作一个 youtube 视频下载器，它工作正常，但如果 youtube 视频 id 有一个类似 - 或 _ 的字符，它会显示一个错误未定义的索引 url，似乎 php 没有看到这个字符 e ,g 如果 youtube 视频 id 是 N65RvNkZFGE 它会工作，但如果它像 wXhTHyIgQ_U 它不会工作因为下划线的原因这里是代码：

// Check whether the url is valid 
    if(!empty($youtubeURL) && !filter_var($youtubeURL, FILTER_VALIDATE_URL) === false){ 
    // Get the downloader object 
    $downloader = $handler->getDownloader($youtubeURL); 

    // Set the url 
    $downloader->setUrl($youtubeURL); 

    // Validate the youtube video url 
    if($downloader->hasVideo()){ 
        // Get the video download link info 
        $videoDownloadLink = $downloader->getVideoDownloadLink(); 

        $videoTitle = $videoDownloadLink[0]['title']; 
        $videoQuality = $videoDownloadLink[0]['qualityLabel']; 
        $videoFormat = $videoDownloadLink[0]['format']; 
        $videoFileName = strtolower(str_replace(' ', '_', $videoTitle)).'.'.$videoFormat; 
        $downloadURL = $videoDownloadLink[0]['url']; 
        $fileName = preg_replace('/[^A-Za-z0-9.\_\-]/', '', basename($videoFileName)); 

包含 setUrl() 函数的 YouTubeDownloader.class.php 文件，获取 extractVideoId() 的代码如下：

     public function setUrl($url){ 
        $this->video_url = $url; 
    } 

private function extractVideoId($video_url){ 
        //parse the url 
        $parsed_url = parse_url($video_url); 
        if($parsed_url["path"] == "youtube.com/watch"){ 
            $this->video_url = "https://www.".$video_url; 
        }elseif($parsed_url["path"] == "www.youtube.com/watch"){ 
            $this->video_url = "https://".$video_url; 
        } 

        if(isset($parsed_url["query"])){ 
            $query_string = $parsed_url["query"]; 
            //parse the string separated by '&' to array 
            parse_str($query_string, $query_arr); 
            if(isset($query_arr["v"])){ 
                return $query_arr["v"]; 
            } 
        }    
    } 

Answer 1

它与“_”或“-”无关。 “n85KukOXc0A”也不起作用。有些视频不返回“url”字段，而是“cipher”。 YouTube 试图混淆 URL。

您的$videoDownloadLink，对于视频 ID“wXhTHyIgQ_U”，如下所示：

array (
  0 => 
  array (
    'itag' => 18,
    'bitrate' => 568627,
    'width' => 640,
    'height' => 360,
    'lastModified' => '1575010363774854',
    'contentLength' => '16085704',
    'quality' => 'medium',
    'qualityLabel' => '360p',
    'projectionType' => 'RECTANGULAR',
    'averageBitrate' => 568472,
    'audioQuality' => 'AUDIO_QUALITY_LOW',
    'approxDurationMs' => '226371',
    'audioSampleRate' => '44100',
    'audioChannels' => 2,
    'cipher' => 's=__L8kZ2zTIc_OfmovvG91jyFU3WN4QTERuPCxA7rHfbHICEhCrCQkmqPth6pmfw5wmrIPOT_ijWceGCWdCeK-lVYXgIARwMGkhKDv&url=https%3A%2F%2Fr4---sn-hpa7kn7s.googlevideo.com%2Fvideoplayback%3Fexpire%3D1583898090%26ei%3DigloXtGYD4bngAeu8YXQCg%26ip%3D2a00%253Aee2%253A1200%253Ae400%253A8c11%253A6897%253A2e00%253Abef0%26id%3Do-AAcaOp-0syooPWmAUuzOfm6gHGPWYCiDlfa-RNdIP34W%26itag%3D18%26source%3Dyoutube%26requiressl%3Dyes%26mm%3D31%252C26%26mn%3Dsn-hpa7kn7s%252Csn-nv47lnly%26ms%3Dau%252Conr%26mv%3Dm%26mvi%3D3%26pl%3D32%26gcr%3Dsi%26initcwndbps%3D1023750%26vprv%3D1%26mime%3Dvideo%252Fmp4%26gir%3Dyes%26clen%3D16085704%26ratebypass%3Dyes%26dur%3D226.371%26lmt%3D1575010363774854%26mt%3D1583876448%26fvip%3D4%26fexp%3D23842630%26c%3DWEB%26txp%3D5531432%26sparams%3Dexpire%252Cei%252Cip%252Cid%252Citag%252Csource%252Crequiressl%252Cgcr%252Cvprv%252Cmime%252Cgir%252Cclen%252Cratebypass%252Cdur%252Clmt%26lsparams%3Dmm%252Cmn%252Cms%252Cmv%252Cmvi%252Cpl%252Cinitcwndbps%26lsig%3DABSNjpQwRQIgBvV2KI0zNTv-7PsmdoRnpyNBvxeMRJIHSlKjfScxihcCIQDlHa5A-1cGAVReyssZ4YkH2nV2rdN1fel6_-Bkv7CAjA%253D%253D&sp=sig',
    'title' => 'Post Malone - Circles',
    'mime' => 'video/mp4',
    'format' => 'mp4',
  ),
)

如您所见，没有“url”字段，但有一个“cipher”字段。
如果我们使用parse_str($videoDownloadLink[0]['cipher'], $cipher) 对其进行解码，我们会得到：

array (
  's' => '__L8kZ2zTIc_OfmovvG91jyFU3WN4QTERuPCxA7rHfbHICEhCrCQkmqPth6pmfw5wmrIPOT_ijWceGCWdCeK-lVYXgIARwMGkhKDv',
  'url' => 'https://r4---sn-hpa7kn7s.googlevideo.com/videoplayback?expire=1583898090&ei=igloXtGYD4bngAeu8YXQCg&ip=2a00%3Aee2%3A1200%3Ae400%3A8c11%3A6897%3A2e00%3Abef0&id=o-AAcaOp-0syooPWmAUuzOfm6gHGPWYCiDlfa-RNdIP34W&itag=18&source=youtube&requiressl=yes&mm=31%2C26&mn=sn-hpa7kn7s%2Csn-nv47lnly&ms=au%2Conr&mv=m&mvi=3&pl=32&gcr=si&initcwndbps=1023750&vprv=1&mime=video%2Fmp4&gir=yes&clen=16085704&ratebypass=yes&dur=226.371&lmt=1575010363774854&mt=1583876448&fvip=4&fexp=23842630&c=WEB&txp=5531432&sparams=expire%2Cei%2Cip%2Cid%2Citag%2Csource%2Crequiressl%2Cgcr%2Cvprv%2Cmime%2Cgir%2Cclen%2Cratebypass%2Cdur%2Clmt&lsparams=mm%2Cmn%2Cms%2Cmv%2Cmvi%2Cpl%2Cinitcwndbps&lsig=ABSNjpQwRQIgBvV2KI0zNTv-7PsmdoRnpyNBvxeMRJIHSlKjfScxihcCIQDlHa5A-1cGAVReyssZ4YkH2nV2rdN1fel6_-Bkv7CAjA%3D%3D',
  'sp' => 'sig',
)

您需要正确打乱“s”字段值并将其作为以“sp”字段值命名的字段添加到 URL。
它需要被加扰的方式会定期改变。目前来自https://www.youtube.com/yts/jsbin/player_ias-vfle4a9aa/en_US/base.js的方式是：

var Ps = 函数(a) { a = a.split(""); os.Dw(a, 1); os.hZ(a, 21); 奥斯安（一，24）； os.hZ(a, 34); os.hZ(a, 18); os.hZ(a, 63); 返回 a.join("") };

var Os = {
    Dw: function(a, b) {
        a.splice(0, b)
    },
    An: function(a) {
        a.reverse()
    },
    hZ: function(a, b) {
        var c = a[0];
        a[0] = a[b % a.length];
        a[b % a.length] = c
    }
};

翻译成 PHP 为：

function scramble($a) {
    $a = str_split($a);
    scr_splice($a, 1);
    scr_swap($a, 21);
    scr_reverse($a, 24);
    scr_swap($a, 34);
    scr_swap($a, 18);
    scr_swap($a, 63);
    return implode('', $a);
}

function scr_reverse(&$a) {
    $a = array_reverse($a);
}
function scr_splice(&$a, $b) {
    array_splice($a, 0, $b);
}
function scr_swap(&$a, $b) {
    $c = $a[0];
    $a[0] = $a[$b % count($a)];
    $a[$b % count($a)] = $c;
}

在您的代码中，您需要检查获得的 URL 类型并获取正确的 URL。

if (isset($videoDownloadLink[0]['url'])) {
    $downloadURL = $videoDownloadLink[0]['url'];
}
else if (isset($videoDownloadLink[0]['cipher'])) {
    parse_str($videoDownloadLink[0]['cipher'], $cipher);
    $downloadURL = $cipher['url']."&".$cipher["sp"]."=".scramble($cipher["s"]);
}
else {
    die('Error getting YouTube URL!');
}

注意：
这只会在 YouTube 再次改变其加扰方式之前有效。