Vcat script: cut & merge video segments

A Python script that wraps moviepy (that in turn wraps `ffmpeg`) to allow mixing and merging segments from other videos in a final video. Tested with mp4 (h.264/mp3) videos all with the same resolution.

Use it with `vcat -i inputfile1,inputfile2[start-end],… -o <outputfile>`

#!/usr/bin/python3

import sys, getopt, re

def printerror(errormsg):
  print("*** vcat - concatenate video segments using moviepy ***\n")
  print("ERROR:", errormsg,"\n")
  print("Usage: vcat -i inputfile1,inputfile2[start-end],... -o <outputfile>")
  print("Optional start and end points should be given in seconds. If files have spaces, they should be quoted (e.g. \"input file.mp4[5-30]\").")

try:
 from moviepy.editor import VideoFileClip, concatenate_videoclips
except ImportError:
 printerror("You don't seem to have moviepy installed. Install it with `pip install moviepy`.")
 exit(1)

def main(argv):
    inputfiles_arg = ''
    outputfile = ''
    try:
        opts, args = getopt.getopt(argv,"hi:o:",["input=","output="])
    except getopt.GetoptError as err:
        printerror(str(err))
        sys.exit(2)
    for opt, arg in opts:
        if opt == '-h':
            printerror("")
            sys.exit()
        elif opt in ("-i", "--input"):
            inputfiles_arg = arg
        elif opt in ("-o", "--output"):
            outputfile = arg
    if outputfile =='':
        printerror("Output file not specified")
    
    iFiles = inputfiles_arg.split(',')

    clips=[]
    for iFile in iFiles:
        subclip = re.search(r"\[([0-9\-]+)\]", iFile)
        if subclip is None:
            clips.append(VideoFileClip(iFile))
        else:
            dims = subclip.group(1).split('-')
            if len(dims) != 2:
                printerror("If a specific segment of a file is specified, this should be given as [startseconds-endseconds]")
            iFile = iFile.replace("["+subclip.group(1)+"]",'')
            clips.append(VideoFileClip(iFile).subclip(int(dims[0]),int(dims[1])))

    f = concatenate_videoclips(clips)
    f.write_videofile(outputfile)