PHP get size of portion of video - php

Question

How do you get the size of a portion of a video? I want to get the size of one minute of a video. Is this possible?
I am making a php video streaming script and I realized that you cannot skip forward. This is what I plan to do: If a user skips forward one minute, I calculate the size of one minute of the video. Then I echo out the video, but skip the first minute.
This is my current code:
function readfile_chunked($filename, $retbytes = TRUE) {
$buffer = "";
$cnt = 0;
$handle = fopen($filename, 'rb');
if ($handle === false) {
return false;
}
while (!feof($handle)) {
$buffer = fread($handle, CHUNK_SIZE);
echo $buffer;
ob_flush();
flush();
if ($retbytes) {
$cnt += strlen($buffer);
}
}
$status = fclose($handle);
if ($retbytes && $status) {
return $cnt; // return num. bytes delivered like readfile() does.
}
return $status;
}
I also have a content-type header that I didn't include in the code above.
Thanks for all your help!

Answer 1

Its not how "skipping" is done.
What you should be doing is looking for the HTTP_RANGE headers that will be sent by the player.
Within your PHP you need to add and then handle the header('Accept-Ranges: bytes'); header.
So when a user clicks to skip forward in the video the player will send a $_SERVER['HTTP_RANGE'] to the server, you then use this to seek to the part of the file for output.
Here is and example (untested):
<?php
...
...
//check if http_range is sent by browser (or download manager)
if(isset($_SERVER['HTTP_RANGE'])){
list($size_unit, $range_orig) = explode('=', $_SERVER['HTTP_RANGE'], 2);
if ($size_unit == 'bytes'){
//multiple ranges could be specified at the same time, but for simplicity only serve the first range
//http://tools.ietf.org/id/draft-ietf-http-range-retrieval-00.txt
list($range, $extra_ranges) = explode(',', $range_orig, 2);
}else{
$range = '';
header('HTTP/1.1 416 Requested Range Not Satisfiable');
exit;
}
}else{
$range = '';
}
//figure out download piece from range (if set)
list($seek_start, $seek_end) = explode('-', $range, 2);
//set start and end based on range (if set), else set defaults
//also check for invalid ranges.
$seek_end = (empty($seek_end)) ? ($file_size - 1) : min(abs(intval($seek_end)),($file_size - 1));
$seek_start = (empty($seek_start) || $seek_end < abs(intval($seek_start))) ? 0 : max(abs(intval($seek_start)),0);
//Only send partial content header if downloading a piece of the file (IE workaround)
if ($seek_start > 0 || $seek_end < ($file_size - 1)){
header('HTTP/1.1 206 Partial Content');
header('Content-Range: bytes '.$seek_start.'-'.$seek_end.'/'.$file_size);
header('Content-Length: '.($seek_end - $seek_start + 1));
}else{
header("Content-Length: $file_size");
}
header('Accept-Ranges: bytes');
...
...
?>
There is also a previous question here you may find usefull, which will be much easyier to implement.