Pad for DTS encoding

@ECHO OFF
TITLE "DTS Pad"
if [%1]==[] goto :eof
set Destination=%~d1\%~p1
set /A frame=512
set Destination=%~d1\%~p1
cd /d %Destination%
md Padded
cd /d "%~dp0"
:loop
for /f %%i in ('soxi -s "%~1"') do set /A length=%%i
set /A pad=(%frame%-%length%%%frame%)
if %pad%==%frame% set /A pad=0
echo %pad% >"%Destination%\%~n1"_pad.txt
sox "%~1" "%Destination%\Padded\%~n1"_pad.wav pad 0s %pad%s
shift
if not [%1]==[] goto loop