bulk_convert.py

# the code is explained here: https://youtu.be/Eex4zBc9r7Y
import os

def main():
    files = os.listdir("./")
    for f in files:
        if f.lower()[-3:] == "mp4":
            print "processing", f
            process(f)

def process(f):
    inFile = f
    outFile = f[:-3] + "mp3"
    cmd = "ffmpeg -i {} -vn  -ac 2 -ar 44100 -ab 320k -f mp3 {}".format(inFile, outFile)
    os.popen(cmd)

main()

code doesnt seem to work if the video file name have spaces in between. for eg. sample video.mp4
is there a solution for that?

De python code executes some command-line script. If a file name has spaces, it should be called within quotes. So try to replace:
cmd = "ffmpeg -i {} -vn -ac 2 -ar 44100 -ab 320k -f mp3 {}".format(inFile, outFile)
with:
cmd = '''ffmpeg -i "{}" -vn -ac 2 -ar 44100 -ab 320k -f mp3 "{}"'''.format(inFile, outFile)

Works In Windows 10 1909 Build 18363.535 And Python 3.8.1 With Cmd Change
cmd = '''ffmpeg -i "{}" -vn -ac 2 -ar 44100 -ab 320k -f mp3 "{}"'''.format(inFile, outFile)
Many Thanks For The Script