@echo off
if [%1]==[] goto:get
echo %1
set vid=%1
set name=%~n1_converted

:convert
echo %vid% to %name%
ffmpeg.exe -i %vid% -c:v libx264 -crf 25 -preset slow -c:a copy "%name%".mp4
goto:EOF

:get
set /p vid=Drag and drop video to convert: 
set /p name=Output Name: 
goto:convert