chdman.exe -update <alte_chd> <neue_chd>

[START]
@echo off
set old_dir=C:\ALT
set new_dir=C:\NEU
set chdman=C:\chdman.exe
for /F %%a in ('dir /b %old_dir%^|find /v "_ReadMe_.txt"') DO (
if NOT exist "%new_dir%\%%a" (
mkdir "%new_dir%\%%a"
)
for /F %%b in ('dir /b "%old_dir%\%%a"') do (
echo Converting: %%b
"%chdman%" -update "%old_dir%\%%a\%%b" "%new_dir%\%%a\%%b"
)
)
[END]