How to cache remote video - php

Question

I want to play video from a remote server. so I write this function.
$remoteFile = 'blabla.com/video_5GB.mp4';
play($remoteFile);
function play($url){
ini_set('memory_limit', '1024M');
set_time_limit(3600);
ob_start();
if (isset($_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[] = $httap_response_header;
ob_end_clean();
array_map("header", $http_response_header);
readfile($url, false, $cong);
}
The above function works very well in playing videos. But I don't want to burden the remote server
My question is how can I cache video files every 5 hours to my server. if possible, the cache folder contains small files (5MB / 10MB) from remote video

Answer 1

As mentioned in my comment, the following code has been tested only on a small selection of MP4 files. It could probably do with some more work but it does fill your immediate needs as it is.
It uses exec() to spawn a separate process that generates the cache files when they are needed, i.e. on the first request or after 5 hours. Each video must have its own cache folder because the cached chunks are simply called 1, 2, 3, etc. Please see additional comments in the code.
play.php - This is the script that will be called by the users from the browser
<?php
ini_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, $url);
}
}
cache.php - This script will be called by play.php via exec()
<?php
//This script expects as argument 1 a base64 encoded url
if(count($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($cacheFolder))
{
die('Invalid Arguments!');
}
//double check it is not already running
if(is_file($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 script
file_put_contents($cacheFolder.DIRECTORY_SEPARATOR.'caching.log', date('d/m/Y H:i:s'));
//get rid of the old completed log
if(is_file($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');
}