def ffmpeg_escape_filename(filename):
    """Escape a filename that we want to pass to the ffmpeg command line

    That will ensure the filename doesn't start with a '-' (which would raise an error)
    """
    if filename.startswith("-"):
        filename = "./" + filename

    return filename
Escape a filename that we want to pass to the ffmpeg command line

    That will ensure the filename doesn't start with a '-' (which would raise an error)
    
moviepy/tools.py