# -*- coding: utf-8 -*-
import os
listdirs = os.listdir("./")
for i in listdirs:
    if i.endswith(".flv"):
        #print(i)
        #a = i[:-4]
        #b = a + ".mp4"
        #print(b)
        
        #cmd = u'D:\\Desktop\\配置\\ffmpeg.exe -i "' + i + '" -c copy "' +b+ '"'
        #os.system(cmd)
        """
        with open("1.txt","a",encoding="utf-8") as f:
            f.write("file '")
            f.write(i)
            f.write("'\n")
        """
        pass
        
cmd = u'D:\\Desktop\\配置\\ffmpeg.exe -f concat -safe 0 -i 1.txt -c copy last.mp4'
os.system(cmd)

由于网络问题，一段视频被下载成无数段，突然想到了python可以解决。