1. batch to mp4 
    for %%a in ("*.*") do ffmpeg -i "%%a" -c:v copy -c:a aac -b:a 128k "newfiles\%%~na.mp4"
pause
  2. combine to one 
    (for %%i in (*.mp4) do @echo file '%%i') > mylist.txt
ffmpeg -f concat -safe 0 -i mylist.txt -c copy myvideo.mp4
  3. mp4 to mp3 
    for %%a in ("*.*") do ffmpeg -i "%%a" -acodec copy -vn "newfiles\%%~na.aac"
pause

    for %%a in ("*.*") do ffmpeg -i "%%a" -acodec libmp3lame "newfiles\%%~na.mp3"
pause
  4. adjust volume 
    for %%a in ("*.*") do ffmpeg -i "%%a" -c:v copy -af "volume=2" "newfiles\%%~na.mp4"
pause
  5. capture 
    ffmpeg -i 0005.mp4 -f image2 -vf fps=fps=1/0.5 -qscale:v 2 mp4-%05d.jpg
  6. screen size (1) 
    ffmpeg -i 0005.mp4 -filter:v "pad=ih*16/9:ih:(ow-iw)/2:(oh-ih)/2" -c:a copy output.mp4

    (2)

    ffmpeg -i 0005.mp4 -vf scale=1920:1080 06.mp4
  7. change audio 
    ffmpeg -i v.mp4 -i a.wav -c:v copy -map 0:v:0 -map 1:a:0 new.mp4