Image creation using php - php

Question

Am trying to create a video clip using .jpg images and ffmpeg, am creating .jpg images as below:
$str=$_REQUEST['data_array'];//gets the base64 encoded image data;
$count =$_REQUEST['count'];//gets number of images i've to create;
$edited_str=substr($str,23,strlen($str)-1);//
$edited_str=base64_decode($edited_str);
$f=fopen("Images/temp".$count.".jpg","w");//am creating temp.jpg file
fwrite($f,$edited_str);//placing my decoded data into file
fclose($f);
are the images am creating above different from normal .jpg images?

Answer 1

This line:
$edited_str=substr($str,23,strlen($str)-1);
makes it different. If this is the full base64 sting of the file, then this cuts it up and corrupts it. Maybe you are adding some stuff on the front.
If you are just removing stuff from the front that was added, then it should be the same as the original file that was encoded with base64.
If you want to get the information this way from another page, I suggest using $_POST as opposed to $_REQUEST for a number of reasons.
EDIT: I wouldn't say video manipulation in php is impossible. I think there is even a toolkit... here's one:
http://phpvideotoolkit.sourceforge.net/
which states:
It can perform video format conversion, extract video frames into separate image files, and assemble a video stream from a set of separate video images.
Haven't tested it, but plan to try it out one day.
EDIT2: On the php site, there were some issues that you could try, but to help more, there needs to be more information. Check with a file directly to make sure it's being sent and decrypted properly.
I haven't got to test any of these yet.
One piece of advice was for large files use:
$decodedstring=base64_decode(chunk_split($encodedstring));
Another was if you use javascript canvas.toDataURL() then you need to convert spaces back to pluses:
$encodedData = str_replace(' ','+',$encodedData);
$decocedData = base64_decode($encodedData);
http://php.net/manual/en/function.base64-decode.php