Concat flv video parts to mp4

Video downloaded by bilibili for mac can be segments of video in flv files, which is not suitable for storage or transmit afterwards.

File tree example:

.
├── 6335305-1.flv
├── 6335305-10.flv
├── 6335305-11.flv
├── 6335305-12.flv
├── 6335305-13.flv
├── 6335305-14.flv
├── 6335305-15.flv
├── 6335305-16.flv
├── 6335305-17.flv
├── 6335305-18.flv
├── 6335305-19.flv
├── 6335305-2.flv
├── 6335305-3.flv
├── 6335305-4.flv
├── 6335305-5.flv
├── 6335305-6.flv
├── 6335305-7.flv
├── 6335305-8.flv
├── 6335305-9.flv
└── 6335305.xml

Can use ffmpeg to concat the video segments to a single file

#!/usr/bin/python
# -*- coding: UTF-8 -*- 
import os
import sys
import re
import subprocess

def tryint(s):
    try:
        return int(s)
    except:
        return s

def alphanum_key(s):
    """ Turn a string into a list of string and number chunks.
        "z23a" -> ["z", 23, "a"]
    """
    return [ tryint(c) for c in re.split('([0-9]+)', s) ]

def sort_nicely(l):
    """ Sort the given list in the way that humans expect.
    """
    l.sort(key=alphanum_key)

def writeInput(items):
    with open('input.txt','w') as f:
        for i in items:
            f.write("file '"+i+"'\n")

def removeItmes(items):
    for item in items:
        os.remove(item)
        
if __name__=="__main__":
    path = sys.argv[1];
    if os.path.exists(path):
        os.chdir(path)
        items=os.listdir('.')
        items=[files for files in items if 'flv' in files]
        sort_nicely(items)
        writeInput(items)
        string='ffmpeg -y -f concat -i input.txt -c copy "%(output)s.mp4"' % {'output':os.path.basename(os.path.abspath(path))}
        subprocess.call(string,shell=True)
        os.remove('input.txt')
        removeItmes(items) //auto remove flv files

Reference: