A problem about exec ffmpeg

[free2003]

I want to exec ffmpeg in my program

My test code is as follows:

if ((ppid = fork()) == 0)
{
execl("/bin/sh", "sh", "-c", "./ffmpeg -i ./sample1.mp4 -vcodec libx264 -b 768k -r 29.97 -s 400x300 test.mp4" , NULL);
}

But when I exec this code, ffmpeg is blocked in "Press [q] to stop encoding", and test.mp4 file is always 48KB.

Where my problem is ?

Thanks.

[Rubberman]

Why are you creating a shell to run ffmpeg? In any case, the current process is being superceded by /bin/sh. The ffmpeg application needs a real device for stdout, stderr, and stdin, so if this application was not being starting in a terminal/console, it will hang. You can redirect I/O to /dev/null and that will probably work, even if you aren't running this application in a terminal/console.