Encrypting (large) files in PHP with openSSL

Question

I\'m trying to encrypt (big) files in PHP using AES and have looked into using Mcrypt and OpenSSL, the problem is all solutions I have found so far only encrypt strings, and

Answer 1

http://www.shellhacks.com/en/Encrypt-And-Decrypt-Files-With-A-Password-Using-OpenSSL

$ openssl enc -aes-256-cbc -salt -in file.txt -out file.txt.enc

to not use too much memory, you want a stream cipher. Call this in PHP with backticks `

or with shell_exec

Edit

As shell exec is not available

http://jeremycook.ca/2011/03/20/easy-file-encryption/

There is a solution there. Though and I can't stress this enough. Stream ciphers are hard I have not reviewed the code there fully nor do I think I am capable. Using open SSL directly is a much better option

http://php.net/manual/en/filters.encryption.php

Is the example code