add 30fps limiter

it's probably gonna get re-rendered anyway

pack-vid

@@ -145,10 +145,13 @@ function convert( $src, $dest, $options ) {
     }
     $vf = implode( ',', $filters );
 
+    $fps = 30;
+
     run( 'ffmpeg',
         array_merge( [
             '-i', $src,
             '-f', 'mp4',
+            '-r', $fps,
             '-vf', $vf,
             '-c:v', 'libx264',
             '-b:v', $bitrate,
@@ -163,6 +166,7 @@ function convert( $src, $dest, $options ) {
         array_merge( [
             '-i', $src,
             '-vf', $vf,
+            '-r', $fps,
             '-c:v', 'libx264',
             '-b:v', $bitrate,
             '-preset', 'veryslow',