Merging different size/format video with avconv and MP4Box

#!/usr/bin/python

"""
Script: avmerge.py
Author: Sergey "Qiwichupa" Pavlov
Version: 2.03

This script was created for merging stream parts from twitch.tv service (but should be versatile). Sometimes it is very simple task, but sometimes resizing and reencoding is needed.
Ok, to the code. First of all this script was written for executing in current directory. I use 'os.listdir' for searching files by extension ('fileExt' variable). Then I use 'avconv' for scaling to 'maxWidth' and 'maxHeight', adding black borders if it's needed, and reencoding video to mp4 container with 'libx264' and 'libmp3lame' codecs. In the end I merge temporary files into one 'out.mp4' with 'MP4Box' from GPAC package.

This script was tested on Linux Mint with:
avconv version 0.8.10-6:0.8.10-0ubuntu0.13.10.1
MP4Box - GPAC version 0.5.1-DEV-rev4065
also it's fully operational on Windows 7 x64 with 'avconv' and 'MP4Box' binaries from http://win32.libav.org/win64/ and http://gpac.wp.mines-telecom.fr/downloads/, and Python installed of course.

Thanks to Kevin Locke for his mighty scale options: http://kevinlocke.name/bits/2012/08/25/letterboxing-with-ffmpeg-avconv-for-mobile/

ChangeLog:
=== 2.03 ===
* First parameter for MP4Box (in 'mp4boxmerge' function, outside the cycle) was changed from '-add' to '-cat'. This part of code must be rewritten in the future.
=== 2.02 ===
* minor fix
=== 2.01 ===
* minor fix
=== 2.0 ===
+ default Width/Heigth options for wide resolution
+ params module with wide/resolution rewrite/extention rewrite options
= code rewrite and optimizing
"""

import os
import subprocess
import argparse

# # # # # # # #
# # SETTINGS  #
# # # # # # # #

# Width and Height default value
maxWidth  = '960'
maxHeight = '720'
# Width and Height default value for -w (--wide) option
maxWidthWide  = '1280'
maxHeightWide = '720'
# Tool path
# (Use absolute path in windows (for example: 'C:\Program Files\GPAC\MP4Box')
# if MP4Box.exe and avconv.exe not in PATH-folders)
MP4BoxCmd = 'MP4Box'
avconvCmd = 'avconv'
# default extention of source files
fileExt   = '.flv'



# # # # # # # # # #
# # HELP & PARAMS #
# # # # # # # # # #

parser = argparse.ArgumentParser(prog='avmerge.py', description='Script for merging video files with re-encoding. Run it from directory with video files. Use "Settings" section of script for tuning.')
resolutionArgsGroup = parser.add_mutually_exclusive_group()
resolutionArgsGroup.add_argument("-r", "--resolution", metavar=('W','H'), type=int, nargs=2, help="rewrite resolution settings with 'Width Height'")
resolutionArgsGroup.add_argument("-w", "--wide", help= "use wide resolution from in-script settings", action="store_true")
parser.add_argument('-e', '--extention', type=str, help='rewrite extention option (use "ext" or ".ext" format as you like)' )
args = parser.parse_args()

if args.wide:
    maxWidth  = maxWidthWide
    maxHeight = maxHeightWide
if args.resolution:
    maxWidth  = str(args.resolution[0])
    maxHeight = str(args.resolution[1])
if args.extention:
   fileExt = args.extention


# # # # # # # #
# # FUNCTIONS #
# # # # # # # #

def avconvert (avconvPath, sourceFile, maxWidth, maxHeight):
    #import os
    #import subprocess

    frameRate    = '30'
    outFile      = "tmp_" + sourceFile + ".mp4"
    scaleOptions = 'scale=iw*sar*min(' + maxWidth + '/(iw*sar)\,' + maxHeight + '/ih):ih*min(' + maxWidth+ '/(iw*sar)\,' + maxHeight + '/ih),pad=' + maxWidth+ ':' + maxHeight + ':(ow-iw)/2:(oh-ih)/2'
    convertCmdString = [avconvPath,
                  '-i', sourceFile,
                  '-map', '0',
                  '-vf',  scaleOptions,
                  '-c:a', 'libmp3lame', #libvo_aacenc, libmp3lame
                  '-ar', '48000',
#                 '-ab', '128k',    # uncomment for constant audio bitrate
#                 '-async', '30',       # uncomment if audio is not synchronized after converting
                  '-c:v', 'libx264',
                  '-r', frameRate,
                  '-bf', '2',
                  '-g', '30',
                  '-profile:v', 'high',
                  '-preset', 'fast',
                  '-level', '42',
                  outFile]
    if os.path.isfile(outFile):
        print('File Exist: ' + outFile)
    else:
        output = subprocess.Popen(convertCmdString).communicate()
        print(output)
    return os.path.abspath(outFile)

def mp4boxmerge (MP4BoxCmd, inFiles, outFile):
    #import os
    #import subprocess

    if len(inFiles) > 1:
        MP4BoxCmdString = []
        MP4BoxCmdString.append(MP4BoxCmd)
        MP4BoxCmdString.append('-cat')
        MP4BoxCmdString.append(inFiles[0])
        for i in range (1,len(inFiles)):
            MP4BoxCmdString.append('-cat')
            MP4BoxCmdString.append(inFiles[i])
        MP4BoxCmdString.append(outFile)
        output = subprocess.Popen(MP4BoxCmdString).communicate()
        print(output)



# # # # # # # #
# # MAIN CODE #
# # # # # # # #

convertedFiles = []

for inFile in sorted(os.listdir('.')):
    if not inFile.endswith(fileExt):
        continue
    outFile  = avconvert(avconvCmd, inFile, maxWidth, maxHeight)
    convertedFiles.append(outFile)


mp4boxmerge(MP4BoxCmd,convertedFiles,'out.mp4')