Try something like this??? not sure if it'd keep adding to the output.mp4 though or overwrite it.
Code:
@echo off
:loop
echo Setting current segment timestamp.
SET hour=%time:~0,2%
IF "%hour:~0,1%" == " " SET hour=0%hour:~1,1%
SET min=%time:~3,2%
IF "%min:~0,1%" == " " SET min=0%min:~1,1%
SET secs=%time:~6,2%
IF "%secs:~0,1%" == " " SET secs=0%secs:~1,1%
SET year=%date:~-4%
SET month=%date:~3,2%
IF "%month:~0,1%" == " " SET month=0%month:~1,1%
SET day=%date:~0,2%
IF "%day:~0,1%" == " " SET day=0%day:~1,1%
SET _my_datetime=%day%-%month%-%year%_%hour%-%min%-%secs%
SET file=%_my_datetime%
-o "%file%_stream.tmp"
echo Join segments into one single stream file.
(for %i in (*.tmp) do @echo file '%i') > mylist.txt
ffmpeg -f concat -i mylist.txt -c copy output.mp4
echo Delete previous tmp segments and mylist.txt
for /f %%F in ('dir /b /a-d ^| findstr /vile ".mp4"') do del "%%F"
goto loop