VideoAudioCombine.bas

#include "windows.bi"

dim as WIN32_FIND_DATA wfd
Dim as string sVideo, sAudio

dim as HANDLE hFind = FindFirstFile("*", @wfd)
do
    if wfd.dwFileAttributes AND FILE_ATTRIBUTE_DIRECTORY then
        sVideo = wfd.cFileName+"\"+Dir(wfd.cFileName+"\*.mp4")
        sAudio = wfd.cFileName+"\"+Dir(wfd.cFileName+"\*.m4a")

        dim as string sCmd = "ffmpeg -i """+sVideo+""" -i """+sAudio+ _
                             """ -c:v copy -c:a aac -map 0:v:0 -map 1:a:0 -shortest """+ _
                             wfd.cFileName+"\output.mp4"""
        print sCmd
        shell sCmd
    end if
loop until (FindNextFile(hFind, @wfd) = 0)

print
print "Finished converting directory!"
print "Press any key to exit..."
sleep