ffmpeg : error when added scale

Question

I am trying to encode batch mkv videos which will give a output with a watermark in it.

But when I add the -vf 840:480 or other resolution (like 720p or 1080p), it don't run but without -vf scale it works fine but I need to set resolution for the video.

Without -vf

for %%I in ("*.mkv") do ffmpeg.exe -i "%%I" -i a.png -filter_complex "[0:v][1:v] overlay=25:25:enable='between(t,0,20)'" -map 0 -vf scale=840:480 -codec:v libx264 -preset veryfast -crf 18 -codec:a copy "480\%%~nI.mkv"

With -vf

for %%I in ("*.mkv") do ffmpeg.exe -i "%%I" -i a.png -filter_complex "[0:v][1:v] overlay=25:25:enable='between(t,0,20)'" -map 0 -vf scale=840:480 -codec:v libx264 -preset veryfast -crf 18 -codec:a copy "480\%%~nI.mkv"

Please help me with how to run the command with -vf scale

Answer 1

Use

for %%I in ("*.mkv") do ffmpeg.exe -i "%%I" -i a.png -filter_complex "[0:v][1:v] overlay=25:25:enable='between(t,0,20)',scale=840:480[v]" -map [v] -map 0:a -codec:v libx264 -preset veryfast -crf 18 -codec:a copy "480\%%~nI.mkv"

All filters acting upon a stream should be within the same filtergraph.