@echo off
setlocal enabledelayedexpansion

set "input_directory=./input"
set "output_directory=./output"
set "input_extension=.mp4"
set "output_extension=.wav"

for %%i in ("%input_directory%\*%input_extension%") do (
    set "input_file=%%i"
    set "output_file=!output_directory!\!input_file:%input_directory%\=!"
    set "output_file=!output_file:%input_extension%=%output_extension%!"
    ffmpeg -i "!input_file!" -c:a pcm_f32le "!output_file!"
)
@REM -c:a pcm_f32le webm を wav にする

endlocal