Question

我正在尝试修改自定义网络服务器应用以使用HTML5视频。

它提供带有基本<video>标记的HTML5页面，然后需要处理实际内容的请求。

到目前为止，我能让它工作的唯一方法是将整个视频文件加载到内存中，然后在一个响应中将其发回。这不是一个实用的选择。我想逐件服务：发送回来，比方说，100 kb，等待浏览器请求更多。

我看到一个包含以下标题的请求：

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-

我尝试发回部分内容回复：

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

我还收到了一些GET请求，如下所示

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 = ###.###.###.###:##

（没有迹象表明浏览器需要文件的任何特定部分。）无论我发送回浏览器，视频都无法播放。

如上所述，如果我尝试在同一个HTTP数据包中一次发送整个230 MB文件，相同的视频将正常播放。

有没有办法让这一切都能通过部分内容请求很好地工作？我正在使用Firefox进行测试，但它最终需要与所有浏览器一起使用。

Answer 1

我知道这是一个老问题，但如果它有帮助，您可以尝试我们在代码库中使用的以下“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;
}
}

然后你就这样使用它：

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

它将处理发送部分文件或完整文件等，并在此和许多其他情况下很好地适用于我们。希望它有所帮助。

Answer 2

我想要部分范围请求，因为我将进行实时转码，我无法根据请求对文件进行完全转码并提供。

对于您尚未了解完整正文内容的回复（您无法猜测Content-Length，实时编码），请使用块编码：

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

每个块在可用时发送：当编码少量帧或输出缓冲区已满时，生成100kB等等。

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

其中22以十六进制给出块字节长度（0x22 = 34字节）， ; 3rd chunk是额外的块信息（可选），tent...binary....data....chunk3..a是块的内容。

然后，当编码完成并发送所有块时，请按：

结束

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

其中0表示没有更多的块，后跟零或更多预告片（允许的标题字段）在标题中定义（Trailer: Expires和Expires: Wed, 21 Oct 2015 07:28:00 GMT不是必需的）来提供校验和或数字签名等。

如果文件已经生成（没有实时编码），则等效于服务器的响应：

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...

有关详情，请访问：Chunked transfer encoding — Wikipedia，Trailer - HTTP | MDN

HTML5视频和部分范围的HTTP请求

2 个答案: