如何在不创建新窗口的情况下从批处理文件调用批处理文件？

Question

I need to process some audio files. Each file must go through multiple sequential steps, for which I've written a batch file. But I want all the files in the folder to be processed in parallel, for speed. So I've written another batch file which calls the first, in a loop. But when I do that, I end up with multiple command windows, which stay open even when the batch file has closed.

In order of preference, how can I either (a) not have the windows open at all, or (b) have the windows minimised then close when finished; or (c) have the windows open then close when finished.

for %%I in (*.mp3) DO (
    start convert-mp3-to-m4b.bat "%%I"
)

I've managed to achieve (c), with start cmd /c convert-mp3-to-m4b.bat "%%I" /B , but that was more by luck than judgement.

Answer 1

With the help of @Stephan I've ended up with this:

for %%Z in (*.mp3) DO (
    start "converting-audio" /min cmd /c convert-mp3-to-m4b.bat "%%Z"
)

This starts the windows minimised, and closes them after processing. I was also glad of the max <n> trick, although I had to adapt the code a bit. In case it's helpful to anyone else, my script now looks like this:

@echo off
setlocal enabledelayedexpansion
set count=0
set max=4
for %%Z in (*.mp3) DO (
    call :loop
    start "converting-audio" /min cmd /c convert-mp3-to-m4b.bat "%%Z"
)

goto :eof    

:loop
for /f "tokens=* USEBACKQ" %%G IN (`tasklist /fi "windowtitle eq converting-audio" ^| find "cmd.exe" /C`) do ( SET "count=%%G" )
if !count! GEQ !max! call :loop

This processes the files four at a time, and works brilliantly.