This is a bat file that transcodes all audio files in a directory into `.opus` files. I use this neat script to sync my `.flac` library with my mobile library.

convert_to_opus.bat

@echo off

rem Copies the original directory structure from F:\Music to D:\Music
rem xcopy /T %1 %2

Robocopy %1 %2 /E /XF *.flac *.mp3 *.mp4

for /R %1 %%i in (*.flac;*.mp3;*.mp4) do (

    rem check if file exists
    if exist "%~d2%%~pni.opus" (

        echo "%~d2%%~pni.opus" already exists

    ) else (

        echo Converting "%%~fi"

        rem convert to opus

        ffmpeg -v quiet -i "%%~fi" -map 0:a:0 -map_metadata 0 -c:a libopus -b:a 128k -frame_duration 20 "%~d2%%~pni.opus"
    )
)
echo Done
pause