I can capture image from a video using ffmpeg:
$cmd = "ffmpeg -i $video_source -an -ss $second -t 00:00:01 -r 1 -y -vcodec mjpeg -f mjpeg -s 40x25 " . escapeshellarg($video_thubmnail_destinaion) . " 2>&1";
However, using the above syntax will only output a 40x25 image. Is it possible that I can specify one more image size?
Yes it's possible to convert/capture 1 source to multiple destination FFmpeg Documentation clearly describe that http://ffmpeg.org/ffmpeg.html
The syntax you should use is:
$cmd = "ffmpeg -i $video_source -an -ss $second -t 00:00:01 -r 1 -y -vcodec mjpeg -f mjpeg -s 40x25 " . escapeshellarg($video_thubmnail_destinaion) -r1 -y -vcodec mjpeg -f mjpeg -s 128x192 " . escapeshellarg($video_big_thubmnail_destinaion) . " 2>&1";