FFMPEG Decklink recording

@echo off
TITLE Status

echo [ Multi-Cam Recording Setup started. ]
echo:

:: Generate timestamp and file names.
set DATE_STRING=%DATC:~6,4%%DATC:~3,2%%DATC:~0,2%
set TIME_STRING=%TIMC:~0,2%%TIMC:~3,2%
set TIMESTAMP=%DATE_STRING%_%TIME_STRING%

set CAMERA_1_FILENAME="C:\\camera_1_"%TIMESTAMP%
set CAMERA_2_FILENAME="C:\\camera_2_"%TIMESTAMP%
set CAMERA_3_FILENAME="C:\\camera_3_"%TIMESTAMP%

echo Waiting to begin recording.
pause

:: Start recording cameras.
start "FFMPEG: Camera 1" /min "C:\Program Files (x86)\FFmpegGUI\ffmpeg64.exe" -format_code Hp29 -f decklink -i "DeckLink Duo (1)" -f matroska -c:v h264_nvenc -b:v 30M -preset:v default -g 30 -pix_fmt yuv420p -c:a aac -b:a 128k -color_primaries bt709 -color_trc bt709 -colorspace bt709 -ss 2 -y %CAMERA_1_FILENAME%.mkv
echo   Writing Camera 1 to "C:\\camera_1_%TIMESTAMP%.mkv"
start "FFMPEG: Camera 2" /min "C:\Program Files (x86)\FFmpegGUI\ffmpeg64.exe" -format_code Hp29 -f decklink -i "DeckLink Duo (2)" -f matroska -c:v h264_nvenc -b:v 30M -preset:v default -g 30 -pix_fmt yuv420p -c:a aac -b:a 128k -color_primaries bt709 -color_trc bt709 -colorspace bt709 -ss 2 -y %CAMERA_2_FILENAME%.mkv
echo   Writing Camera 2 to "C:\\camera_2_%TIMESTAMP%.mkv"
start "FFMPEG: Camera 3" /min "C:\Program Files (x86)\FFmpegGUI\ffmpeg64.exe" -format_code Hp29 -f decklink -i "DeckLink Duo (3)" -f matroska -c:v h264_nvenc -b:v 30M -preset:v default -g 30 -pix_fmt yuv420p -c:a aac -b:a 128k -color_primaries bt709 -color_trc bt709 -colorspace bt709 -ss 2 -y %CAMERA_3_FILENAME%.mkv
echo   Writing Camera 3 to "C:\\camera_3_%TIMESTAMP%.mkv"
echo:

:: Wait for key press to stop recording.
choice /M "Press X to stop recording..." /N /C X
taskkill /fi "windowtitle eq FFMPEG: Camera 1"
taskkill /fi "windowtitle eq FFMPEG: Camera 2"
taskkill /fi "windowtitle eq FFMPEG: Camera 3"

pause