from glob import glob
import os


for file in glob("*.flv"):
    new_file = file.replace(".flv", ".mp4")
    if os.path.exists(new_file):
        continue
    os.system(" ".join([
        "ffmpeg", "-y", "-i", f"\"{file}\"",
        "-c copy", "-f mp4",
        f"\"{new_file}\"",
    ]))