Question

我在用javascript和php实现视频时遇到问题。

index.php

session_start()

// do other stuff
include ‘video.php’

video.php

<?php
If(!$_REQUEST[‘play’]){
    // displaying video.html
}
else
{
    // play video
$fp = @fopen($file, 'rb');

$size   = filesize($file); // File size
$length = $size;           // Content length
$start  = 0;               // Start byte
$end    = $size - 1;       // End byte

// Now that we've gotten so far without errors we send the accept range header

/* At the moment we only support single ranges.
 * Multiple ranges requires some more work to ensure it works correctly
 * and comply with the spesifications: http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
 *
 * Multirange support annouces itself with:
 * header('Accept-Ranges: bytes');
 *
 * Multirange content must be sent with multipart/byteranges mediatype,
 * (mediatype = mimetype)
 * as well as a boundry header to indicate the various chunks of data.
 */

header('Content-type: video/mp4');
header('Accept-Ranges: bytes');
// multipart/byteranges
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
if (isset($_SERVER['HTTP_RANGE'])){
    $c_start = $start;
    $c_end   = $end;
    // Extract the range string
    list(, $range) = explode('=', $_SERVER['HTTP_RANGE'], 2);
    // Make sure the client hasn't sent us a multibyte range
    if (strpos($range, ',') !== false){
        // (?) Shoud this be issued here, or should the first
        // range be used? Or should the header be ignored and
        // we output the whole content?
        header('HTTP/1.1 416 Requested Range Not Satisfiable');
        header("Content-Range: bytes $start-$end/$size");
        // (?) Echo some info to the client?
        exit;
    } // fim do if

    // If the range starts with an '-' we start from the beginning
    // If not, we forward the file pointer
    // And make sure to get the end byte if spesified
    if ($range{0} == '-'){
        // The n-number of the last bytes is requested
        $c_start = $size - substr($range, 1);
    } else {
        $range  = explode('-', $range);
        $c_start = $range[0];
        $c_end   = (isset($range[1]) && is_numeric($range[1])) ? $range[1] : $size;
    } // fim do if
    /* Check the range and make sure it's treated according to the specs.
     * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
     */
    // End bytes can not be larger than $end.
    $c_end = ($c_end > $end) ? $end : $c_end;
    // Validate the requested range and return an error if it's not correct.
    if ($c_start > $c_end || $c_start > $size - 1 || $c_end >= $size){
        header('HTTP/1.1 416 Requested Range Not Satisfiable');
        header("Content-Range: bytes $start-$end/$size");
        // (?) Echo some info to the client?
        exit;
    } // fim do if

    $start  = $c_start;
    $end    = $c_end;
    $length = $end - $start + 1; // Calculate new content length
    fseek($fp, $start);
    header('HTTP/1.1 206 Partial Content');
} // fim do if

// Notify the client the byte range we'll be outputting
header("Content-Range: bytes $start-$end/$size");
header("Content-Length: $length");
// Start buffered download
$buffer = 1024 * 8;
while(!feof($fp) && ($p = ftell($fp)) <= $end){
    if ($p + $buffer > $end){
        // In case we're only outputtin a chunk, make sure we don't
        // read past the length
        $buffer = $end - $p + 1;
    } // fim do if
    set_time_limit(0); // Reset time limit for big files
    echo fread($fp, $buffer);
    flush(); // Free up memory. Otherwise large files will trigger PHP's memory limit.
 } // fim do while
 fclose($fp);
 exit();
}

video.html

<!doctype html>
<html lang="fr-FR">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
    <body>
        <video controls>
            <source src="index.php?format=mp4&play=1&id=someid type="video/mp4" />
        </video>
    </body>
</html>

一切正常，但是由于某些原因，我不知道，当我开始播放视频，然后单击页面上的链接或使用浏览器的后退按钮时，浏览器会冻结并等待一段时间（变量），然后再执行操作链接。

探查器指示所请求的页面更改处于挂起状态。

如果我将视频光标放在更远的位置，浏览器会立即解锁并跟随我单击的链接。

最后，如果我重新加载该页面，该问题不再出现。 chrome似乎在等待一些东西，但是由于我的缓存已禁用，因此它没有缓存。

这仅在chrome桌面上发生，所有其他浏览器都能正确完成工作。

**编辑**

我找到了问题的根源。

要播放视频，请浏览我的主文件index.php，该文件用作路由器，我在其中使用session_start()初始化会话。

正在播放视频时，我单击链接或浏览器的后退按钮，便返回到index.php。这是Chrome在session_start（）期间卡住的时候

只要播放视频，似乎会话之间就存在冲突。

Answer 1

如果您未在会话中编写任何内容，请在session_write_close()之后使用session_start() juse，或者在此之后再编写一些会话变量。

当我们开始会话时，它将打开会话文件以进行读取。仅在脚本结束后关闭读取。同时，如果您要打开新页面，它将被卡住。因此请使用此功能来阻止它。

https://www.php.net/manual/en/function.session-write-close.php

session_start();
session_write_close();

// do other stuff
include ‘video.php’

您可以在session_write_close（）之后读取会话变量。.那没什么问题..但是，如果您在它之后写东西..它将不会在会话变量中写入该值。

Answer 2

要防止在打开现有会话时尝试重新启动会话，请使用session_status：

if (session_status() == PHP_SESSION_NONE) {
    session_start();
}

即使使用session_write_close，检查现有会话仍然是一种好习惯。

这样，如果您包含多个文件，每个文件都试图启动一个会话，它们将不会彼此踩在一起。

Chrome问题-视频流和会话冲突

2 个答案: