HTML5視頻和部分範圍的HTTP請求

Question

我試圖修改自定義Web服務器應用程序以使用HTML5視頻。

它提供一個基本的<video>標記的HTML5頁面，然後它需要處理實際內容的請求。

到目前爲止，我唯一可以使用它的唯一方法是將整個視頻文件加載到內存中，然後通過單一響應將其發回。這不是一個實際的選擇。我想要一塊一塊地發送它：發回100 kb，並等待瀏覽器請求更多。

我看到下列頭的請求：

http_version = 1.1 
request_method = GET 

Host = ###.###.###.###:## 
User-Agent = Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20100101 Firefox/16.0 
Accept = video/webm,video/ogg,video/*;q=0.9,application/ogg;q=0.7,audio/*;q=0.6,*/*;q=0.5 
Accept-Language = en-US,en;q=0.5 
Connection = keep-alive 
Range = bytes=0- 

我試着發回的部分內容響應：

HTTP/1.1 206 Partial content 
Content-Type: video/mp4 
Content-Range: bytes 0-99999/232725251 
Content-Length: 100000 

我得到一些更多GET請求，如下

Cache-Control = no-cache 
Connection = Keep-Alive 
Pragma = getIfoFileURI.dlna.org 
Accept = */* 
User-Agent = NSPlayer/12.00.7601.17514 WMFSDK/12.00.7601.17514 
GetContentFeatures.DLNA.ORG = 1 
Host = ###.###.###.###:## 

（沒有跡象表明瀏覽器需要該文件的任何特定部分。）無論我發送什麼文件k到瀏覽器，視頻不播放。

如上所述，如果我嘗試在同一個HTTP數據包中一次發送整個230 MB文件，同樣的視頻將正確播放。

有沒有什麼辦法可以很好的完成部分內容請求？我使用Firefox進行測試，但最終需要與所有瀏覽器協同工作。

Answer 1

我知道這是一個老問題，但如果它有幫助，您可以嘗試我們在代碼庫中使用的以下「模型」。

class Model_DownloadableFile { 
private $full_path; 

function __construct($full_path) { 
    $this->full_path = $full_path; 
} 

public function get_full_path() { 
    return $this->full_path; 
} 

// Function borrowed from (been cleaned up and modified slightly): http://stackoverflow.com/questions/157318/resumable-downloads-when-using-php-to-send-the-file/4451376#4451376 
// Allows for resuming paused downloads etc 
public function download_file_in_browser() { 
    // Avoid sending unexpected errors to the client - we should be serving a file, 
    // we don't want to corrupt the data we send 
    @error_reporting(0); 

    // Make sure the files exists, otherwise we are wasting our time 
    if (!file_exists($this->full_path)) { 
     header('HTTP/1.1 404 Not Found'); 
     exit; 
    } 

    // Get the 'Range' header if one was sent 
    if (isset($_SERVER['HTTP_RANGE'])) { 
     $range = $_SERVER['HTTP_RANGE']; // IIS/Some Apache versions 
    } else if ($apache = apache_request_headers()) { // Try Apache again 
     $headers = array(); 
     foreach ($apache as $header => $val) { 
      $headers[strtolower($header)] = $val; 
     } 
     if (isset($headers['range'])) { 
      $range = $headers['range']; 
     } else { 
      $range = false; // We can't get the header/there isn't one set 
     } 
    } else { 
     $range = false; // We can't get the header/there isn't one set 
    } 

    // Get the data range requested (if any) 
    $filesize = filesize($this->full_path); 
    $length = $filesize; 
    if ($range) { 
     $partial = true; 
     list($param, $range) = explode('=', $range); 
     if (strtolower(trim($param)) != 'bytes') { // Bad request - range unit is not 'bytes' 
      header("HTTP/1.1 400 Invalid Request"); 
      exit; 
     } 
     $range = explode(',', $range); 
     $range = explode('-', $range[0]); // We only deal with the first requested range 
     if (count($range) != 2) { // Bad request - 'bytes' parameter is not valid 
      header("HTTP/1.1 400 Invalid Request"); 
      exit; 
     } 
     if ($range[0] === '') { // First number missing, return last $range[1] bytes 
      $end = $filesize - 1; 
      $start = $end - intval($range[0]); 
     } else if ($range[1] === '') { // Second number missing, return from byte $range[0] to end 
      $start = intval($range[0]); 
      $end = $filesize - 1; 
     } else { // Both numbers present, return specific range 
      $start = intval($range[0]); 
      $end = intval($range[1]); 
      if ($end >= $filesize || (!$start && (!$end || $end == ($filesize - 1)))) { 
       $partial = false; 
      } // Invalid range/whole file specified, return whole file 
     } 
     $length = $end - $start + 1; 
    } else { 
     $partial = false; // No range requested 
    } 

    // Determine the content type 
    $finfo = finfo_open(FILEINFO_MIME_TYPE); 
    $contenttype = finfo_file($finfo, $this->full_path); 
    finfo_close($finfo); 

    // Send standard headers 
    header("Content-Type: $contenttype"); 
    header("Content-Length: $length"); 
    header('Content-Disposition: attachment; filename="' . basename($this->full_path) . '"'); 
    header('Accept-Ranges: bytes'); 

    // if requested, send extra headers and part of file... 
    if ($partial) { 
     header('HTTP/1.1 206 Partial Content'); 
     header("Content-Range: bytes $start-$end/$filesize"); 
     if (!$fp = fopen($this->full_path, 'r')) { // Error out if we can't read the file 
      header("HTTP/1.1 500 Internal Server Error"); 
      exit; 
     } 
     if ($start) { 
      fseek($fp, $start); 
     } 
     while ($length) { // Read in blocks of 8KB so we don't chew up memory on the server 
      $read = ($length > 8192) ? 8192 : $length; 
      $length -= $read; 
      print(fread($fp, $read)); 
     } 
     fclose($fp); 
    } else { 
     readfile($this->full_path); // ...otherwise just send the whole file 
    } 

    // Exit here to avoid accidentally sending extra content on the end of the file 
    exit; 
} 
} 

然後你使用這樣的：

(new Model_DownloadableFile('FULL/PATH/TO/FILE'))->download_file_in_browser(); 

它將處理髮送文件或整個文件等的一部分，很適合我們在這方面和許多其他情形。希望能幫助到你。

Answer 2

我想要部分範圍的請求，因爲我會做實時代碼轉換，我不能讓文件完全轉碼並根據請求提供。

爲了響應你不知道的全部主體內容，但（你不能猜出Content-Length，實時編碼），使用塊編碼：

HTTP/1.1 200 OK 
Content-Type: video/mp4 
Transfer-Encoding: chunked 
Trailer: Expires 

1E; 1st chunk 
...binary....data...chunk1..my 
24; 2nd chunk 
video..binary....data....chunk2..con 
22; 3rd chunk 
tent...binary....data....chunk3..a 
2A; 4th chunk 
nd...binary......data......chunk4...etc... 
0 
Expires: Wed, 21 Oct 2015 07:28:00 GMT 

每個塊是發送當它可用：當幾個幀進行編碼時，或者當輸出緩衝器是滿的，100KB的產生等

22; 3rd chunk 
tent...binary....data....chunk3..a 

凡22給在六塊字節長度（爲0x22 = 34個字節）， ; 3rd chunk是額外塊信息（可選），tent...binary....data....chunk3..a是塊的內容。

然後，當編碼完成後，所有組塊被通過發送端：

0 
Expires: Wed, 21 Oct 2015 07:28:00 GMT 

凡0意味着沒有更多組塊，後面的零或多個拖車（允許的報頭字段）中的報頭定義（Trailer: Expires和Expires: Wed, 21 Oct 2015 07:28:00 GMT不需要）提供的校驗和數字簽名等

這裏是服務器的響應相當於如果已經生成文件（沒有實時編碼）：

HTTP/1.1 200 OK 
Content-Type: video/mp4 
Content-Length: 142 
Expires: Wed, 21 Oct 2015 07:28:00 GMT 

...binary....data...chunk1..myvideo..binary....data....chunk2..content...binary....data....chunk3..and...binary......data......chunk4...etc... 

欲瞭解更多信息：Chunked transfer encoding — Wikipedia，Trailer - HTTP | MDN