fix: ffmpeg -vf warn

BatchProcess/Program.cs

@@ -172,8 +172,7 @@ namespace BatchProcess
                         "-map_metadata","-1","-map_chapters","-1",
                         "-shortest",
                         
-                        "-vf","scale=-1:480",
-                        "-vf","pad=ceil(iw/2)*2:ceil(ih/2)*2",
+                        "-vf","scale=-1:480,pad=ceil(iw/2)*2:ceil(ih/2)*2",
 
                         "-c:v","h264","-pix_fmt","yuv420p",
                         "-preset","placebo",