Memory leak using official resumable video upload for Youtube PHP API V3

I try to upload large file in PHP to Youtube, using the API V3.I just copied the official code from there.

It perfectly works for small uploads (<100Mo).But when I try to upload large files, it returns :

    Fatal error: Out of memory (allocated 102760448) (tried to allocate 1048577 bytes) in /homepages/40/d216486693/htdocs/uploadsys.php on line 143

The code I use is just below, and line 143 is $chunk = fread($handle, $chunkSizeBytes);My server can allow some more memory, but what if I try to upload 1GB size files ?In fact, the main problem is that if I check memory usage during the loop with chunk read & send, it never decrease !

It's just like if each chunk stays in memory... What can I do ? Tried to unset $chunk with no success

        $snippet = new Google_Service_YouTube_VideoSnippet();        $filtre1 = array("'","'","'","\'");        $snippet->setTitle(str_replace("\\","",str_replace($filtre1,"’",$title)));        $snippet->setDescription("Descr");        $snippet->setTags(explode(",",$keywords));        $snippet->setCategoryId($ytcat);        $status = new Google_Service_YouTube_VideoStatus();        $status->privacyStatus = "unlisted";        $video = new Google_Service_YouTube_Video();        $video->setSnippet($snippet);        $video->setStatus($status);        $chunkSizeBytes = 1 * 1024 * 1024;        $client->setDefer(true);        $insertRequest = $youtube->videos->insert("status,snippet", $video);        $media = new Google_Http_MediaFileUpload($client,$insertRequest,'video/*',null,true,$chunkSizeBytes);        $file_size = filesize($videofile);        $media->setFileSize($file_size);        // Read the media file and upload it chunk by chunk.        $status = false;        $handle = fopen($videofile, "rb");        $cc = 0;        while (!$status && !feof($handle)) {          //Line 143 below          $chunk = fread($handle, $chunkSizeBytes);          $status = $media->nextChunk($chunk);          $cc++;        }        fclose($handle);