检查php exec的输出始终返回空数组

Question

I'm converting some movies and want to make sure the conversion went through without errors:

exec("ffmpeg -i ".$orgVideoFile." -vcodec libx264 -crf 21 -acodec aac -ac 2 -ab 192000 -strict experimental -vpre hq -vpre veryfast -refs 3 -threads 4 -s 320x240 ".$newVideoFile, $output);
echo "Output:";
var_dump($output);

but when checking $output its always empty:

Output:array(0) { } 

How do I check to make sure everything went ok?

Answer 1

You will have much more control using PHP's proc_open function. It allows you to write/read standard input/output in a very controlled way:

$tunnels=array(
    0 => array('pipe','r'), // Process std input
    1 => array('pipe','w'), // Process std output
    2 => array('pipe','w') // Process std error
    );

$io=array();                      
$resource=proc_open("command with parameters...etc",$tunnels,$io);

if(!is_resource($resource)) {                       
    // Throw exception or something...
}

// Write to process standard input and close stream
fwrite($io[0],"Some data...");
fclose($io[0]);

// We are not interested in process standard output.. close it
fclose($io[1]);               

// Get process std error
$errors=stream_get_contents($io[2]);
fclose($io[2]);

// Close process reousrce
$result=proc_close($resource);

if($result != 0) {          
    // There where errors. Grab the error string from $errors
}         

Answer 2

exec('ffmpeg ...', $output, $return);

if ($return != 0) {
    // an error occurred
}

Answer 3

use php's function

system();

instead. Rather then just having exit code you'll may compare ffmpeg's output against desired value.