I am using a php script for converting avi,mpeg files to flv with ffmpeg.my code is

$srcFile = "uploads/flame.avi";
    $destFile = "uploads/flame.flv";
    $ffmpegPath = "/usr/bin/ffmpeg";
    $flvtool2Path = "/usr/bin/flvtool2";
    $ffmpegObj = new ffmpeg_movie($srcFile);
    $srcWidth = 320;
    $srcHeight = 240;
    $command = $ffmpegPath . " -i " . $srcFile .  " -f flv -s " . $srcWidth . "x" .      $srcHeight . " " . $destFile . " | " . $flvtool2Path . " -U stdin " . $destFile;
    $convert = exec($command);
	echo "FAILED!!!";
        echo "SUCCESS";

I can create a flv file using this script.But sometimes it creates a flv file with size 0 k.I don't know why this is happening.With the same avi file,sometimes it creates correct flv file and sometimes flv with size 0k.How can I confirm whether the conversion is success. In both the cases it displays SUCCESS.

exec() won't give you TRUE or FALSE on the command executed, will simply return an output, and only if you add a second parameter. For example:

echo exec('ls',&$ot) . "\n";
print_r($ot) . "\n";

So, you need to see what is going on during the conversion. Try to use system(), you will get all the output.

Thanks for your reply..But may I know why ffmpeg command produces strange result.Sometimes it neatly converts avi to flv.
And sometimes the same avi is converted to 0 size flv..Is anything wrong in my ffmpeg command