如何缓存远程视频

正如我在评论中提到的，以下代码仅在一小部分 MP4 文件上进行了测试。它可能需要做更多的工作，但它确实满足了您的即时需求。它使用 exec() 生成一个单独的进程，在需要时（即在第一次请求时或 5 小时后）生成缓存文件。每个视频必须有自己的缓存文件夹，因为缓存的块简称为 1、2、3 等。请参阅代码中的其他注释。play.php - 这是用户从浏览器调用的脚本<?phpini_set('memory_limit', '1024M');set_time_limit(3600);$remoteFile = 'blabla.com/video_5GB.mp4';play($remoteFile);/** * @param string $url * * This will serve the video from the remote url */function playFromRemote($url){  ob_start();  $opts = array();  if(isset($_SERVER['HTTP_RANGE']))  {    $opts['http']['header'] = "Range: ".$_SERVER['HTTP_RANGE'];  }  $opts['http']['method'] = "HEAD";  $conh = stream_context_create($opts);  $opts['http']['method'] = "GET";  $cong = stream_context_create($opts);  $out[] = file_get_contents($url, false, $conh);  $out[] = $http_response_header;  ob_end_clean();  $fh = fopen('response.log', 'a');  if($fh !== false)  {    fwrite($fh, print_r($http_response_header, true)."\n\n\n\n");    fclose($fh);  }  array_map("header", $http_response_header);  readfile($url, false, $cong);}/** * @param string $cacheFolder Directory in which to find the cached chunk files * @param string $url * * This will serve the video from the cache, it uses a "completed.log" file which holds the byte ranges of each chunk * this makes it easier to locate the first chunk of a range request. The file is generated by the cache script */function playFromCache($cacheFolder, $url){  $bytesFrom = 0;  $bytesTo = 0;  if(isset($_SERVER['HTTP_RANGE']))  {    //the client asked for a specific range, extract those from the http_range server var    //can take the form "bytes=123-567" or just a from "bytes=123-"    $matches = array();    if(preg_match('/^bytes=(\d+)-(\d+)?$/', $_SERVER['HTTP_RANGE'], $matches))    {      $bytesFrom = intval($matches[1]);      if(!empty($matches[2]))      {        $bytesTo = intval($matches[2]);      }    }  }  //completed log is a json_encoded file containing an array or byte ranges that directly  //correspond with the chunk files generated by the cache script  $log = json_decode(file_get_contents($cacheFolder.DIRECTORY_SEPARATOR.'completed.log'));  $totalBytes = 0;  $chunk = 0;  foreach($log as $ind => $bytes)  {    //find the first chunk file we need to open    if($bytes[0] <= $bytesFrom && $bytes[1] > $bytesFrom)    {      $chunk = $ind + 1;    }    //and while we are at it save the last byte range "to" which is the total number of bytes of all the chunk files    $totalBytes = $bytes[1];  }  if($bytesTo === 0)  {    if($totalBytes === 0)    {      //if we get here then something is wrong with the cache, revert to serving from the remote      playFromRemote($url);      return;    }    $bytesTo = $totalBytes - 1;  }  //calculate how many bytes will be returned in this request  $contentLength = $bytesTo - $bytesFrom + 1;  //send some headers - I have hardcoded MP4 here because that is all I have developed with  //if you are using different video formats then testing and changes will no doubt be required  header('Content-Type: video/mp4');  header('Content-Length: '.$contentLength);  header('Accept-Ranges: bytes');  //Send a header so we can recognise that the content was indeed served by the cache  header('X-Cached-Date: '.(date('Y-m-d H:i:s', filemtime($cacheFolder.DIRECTORY_SEPARATOR.'completed.log'))));  if($bytesFrom > 0)  {    //We are sending back a range so it needs a header and the http response must be 206: Partial Content    header(sprintf('content-range: bytes %s-%s/%s', $bytesFrom, $bytesTo, $totalBytes));    http_response_code(206);  }  $bytesSent = 0;  while(is_file($cacheFolder.DIRECTORY_SEPARATOR.$chunk) && $bytesSent < $contentLength)  {    $cfh = fopen($cacheFolder.DIRECTORY_SEPARATOR.$chunk, 'rb');    if($cfh !== false)    {      //if we are fetching a range then we might need to seek the correct starting point in the first chunk we look at      //this check will be performed on all chunks but only the first one should need seeking so no harm done      if($log[$chunk - 1][0] < $bytesFrom)      {        fseek($cfh, $bytesFrom - $log[$chunk - 1][0]);      }      //read and send data until the end of the file or we have sent what was requested      while(!feof($cfh) && $bytesSent < $contentLength)      {        $data = fread($cfh, 1024);        //check we are not going to be sending too much back and if we are then truncate the data to the correct length        if($bytesSent + strlen($data) > $contentLength)        {          $data = substr($data, 0, $contentLength - $bytesSent);        }        $bytesSent += strlen($data);        echo $data;      }      fclose($cfh);    }    //move to the next chunk    $chunk ++;  }}function play($url){  //I have chosen a simple way to make a folder name, this can be improved any way you need  //IMPORTANT: Each video must have its own cache folder  $cacheFolder = sha1($url);  if(!is_dir($cacheFolder))  {    mkdir($cacheFolder, 0755, true);  }  //First check if we are currently in the process of generating the cache and so just play from remote  if(is_file($cacheFolder.DIRECTORY_SEPARATOR.'caching.log'))  {    playFromRemote($url);  }  //Otherwise check if we have never completed the cache or it was completed 5 hours ago and if so spawn a process to generate the cache  elseif(!is_file($cacheFolder.DIRECTORY_SEPARATOR.'completed.log') || filemtime($cacheFolder.DIRECTORY_SEPARATOR.'completed.log') + (5 * 60 * 60) < time())  {    //fork the caching to a separate process - the & echo $! at the end causes the process to run as a background task    //and print the process ID returning immediately    //The cache script can be anywhere, pass the location to sprintf in the first position    //A base64 encoded url is passed in as argument 1, sprintf second position    $cmd = sprintf('php %scache.php %s & echo $!', __DIR__.DIRECTORY_SEPARATOR, base64_encode($url));    $pid = exec($cmd);    //with that started we need to serve the request from the remote url    playFromRemote($url);  }  else  {    //if we got this far then we have a completed cache so serve from there    playFromCache($cacheFolder, $url);  }}cache.php - 该脚本将由 play.php 通过 exec() 调用<?php//This script expects as argument 1 a base64 encoded urlif(count($argv)!==2){  die('Invalid Request!');}$url = base64_decode($argv[1]);//make sure to use the same method of obtaining the cache folder name as the main play script//or change the code to pass it in as an argument$cacheFolder = sha1($url);if(!is_dir($cacheFolder)){  die('Invalid Arguments!');}//double check it is not already runningif(is_file($cacheFolder.DIRECTORY_SEPARATOR.'caching.log')){  die('Already Running');}//create a file so we know this has started, the file will be removed at the end of the scriptfile_put_contents($cacheFolder.DIRECTORY_SEPARATOR.'caching.log', date('d/m/Y H:i:s'));//get rid of the old completed logif(is_file($cacheFolder.DIRECTORY_SEPARATOR.'completed.log')){  unlink($cacheFolder.DIRECTORY_SEPARATOR.'completed.log');}$bytesFrom = 0;$bytesWritten = 0;$totalBytes = 0;//this is the size of the chunk files, currently 10MB$maxSizeInBytes = 10 * 1024 * 1024;$chunk = 1;//open the url for binary reading and first chunk for binary writing$fh = fopen($url, 'rb');$cfh = fopen($cacheFolder.DIRECTORY_SEPARATOR.$chunk, 'wb');if($fh !== false && $cfh!==false){  $log = array();  while(!feof($fh))  {    $data = fread($fh, 1024);    fwrite($cfh, $data);    $totalBytes += strlen($data); //use actual length here    $bytesWritten += strlen($data);    //if we are on or passed the chunk size then close the chunk and open a new one    //keeping a log of the byte range of the chunk    if($bytesWritten>=$maxSizeInBytes)    {      $log[$chunk-1] = array($bytesFrom,$totalBytes);      $bytesFrom = $totalBytes;      fclose($cfh);      $chunk++;      $bytesWritten = 0;      $cfh = fopen($cacheFolder.DIRECTORY_SEPARATOR.$chunk, 'wb');    }  }  fclose($fh);  $log[$chunk-1] = array($bytesFrom,$totalBytes);  fclose($cfh);  //write the completed log. This is a json encoded string of the chunk byte ranges and will be used  //by the play script to quickly locate the starting chunk of a range request  file_put_contents($cacheFolder.DIRECTORY_SEPARATOR.'completed.log', json_encode($log));  //finally remove the caching log so the play script doesn't think the process is still running  unlink($cacheFolder.DIRECTORY_SEPARATOR.'caching.log');}

如何缓存远程视频

1回答