Ffmpeg by subprocess.Popen: Setting volume by filter doesn't work

Hi there! I’m converting some videos by use of ffmpeg and subprocess.Popen. Everything is working fine but setting the volume does not. My code: # ffmpegPath is defined above startArray = [ ffmpegPath, '-y', '-i', path ] try: # Load player info from file, path is defined above: with open(pathPlayerInfo) as f: playerInfo = json.l...