@ECHO off
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION

SET ffmpeg="C:\ffmpeg\bin\ffmpeg.exe"
:: get selected folder path
SET dir=%1\
SET dir_inside=%1\*

:: loop through files to get image's sequence filename
FOR %%G in (%dir_inside%) do (
    SET filename=%%~nG
    GOTO exit_loop
)

:exit_loop
:: remove trailing numbers from extracted filename
call :strlen length filename
SET /a length -= 4
SET filename=!filename:~0,%length%!
:: construct full file path with number padding for later use in ffmpeg
SET filepath="%dir%%filename%/%04d.png"

:: should be f.e. "D:\Users\mig21\Desktop\dsaads\003 Maziaje%04d.png"
ECHO %filepath%

call %ffmpeg% -r 25 -i %filepath% -c:v libx264 -vf fps=25 -pix_fmt yuv420p out.mp4

PAUSE

:strlen <resultVar> <stringVar>
(
    setlocal EnableDelayedExpansion
    set "s=!%~2!#"
    set "len=0"
    for %%P in (4096 2048 1024 512 256 128 64 32 16 8 4 2 1) do (
        if "!s:~%%P,1!" NEQ "" (
            set /a "len+=%%P"
            set "s=!s:~%%P!"
        )
    )
)
(
    endlocal
    set "%~1=%len%"
    exit /b
)