encode.py

#!/usr/bin/env python

import argparse
import subprocess
import pathlib

parser = argparse.ArgumentParser("Concatenate and encode movies")
parser.add_argument("infiles", nargs='+', 
                    type=argparse.FileType('r'), 
                    help='Files to encode')
parser.add_argument("-o", "--outfile", default=None)
parser.add_argument('--scalewidth', type=int, default=800)
parser.add_argument('--scaleheight', type=int, default=600)

args = parser.parse_args()

# ffmpeg 
# -i CPB410\ 2019-04-10.mov 
# -i CPB410\ 2019-04-10b.mov 
# -filter_complex 
# "[0:v:0]scale=800:600,setsar=1:1[v0];
#  [1:v:0]scale=800:600,setsar=1:1[v1];
#  [v0][0:a:0][v1][1:a:0]concat=n=2:v=1:a=1[outv][au];
#  [au]acompressor=level_in=3:threshold=-21dB:ratio=9:attack=200:release=1000[outa]" 
# -map "[outv]" 
# -map "[outa]" 
# CPB410\ 2019-04-10.mp4

# [0:v:0]scale=800:600,setsar=1:1[v0];
# [1:v:0]scale=800:600,setsar=1:1[v1];
# [v0][0:a:0][v1][1:a:0]concat=n=2:v=1:a=1[outv][au];
# [au]acompressor=level_in=3:threshold=-21dB:ratio=9:attack=200:release=1000[outa]

def notify(s):
    subprocess.call(["notify", s])

audiofilter = "acompressor=level_in=3:threshold=-21dB:ratio=9:attack=200:release=1000,loudnorm"

command = "ffmpeg"

if args.outfile is None:
    args.outfile = pathlib.Path(args.infiles[0].name).with_suffix('.mp4')

encodeargs = []
filterchain = []
concat = ''
for i, infile in enumerate(args.infiles):
    encodeargs += ["-i", infile.name]
    filterchain.append(f"[{i}:v:0]scale={args.scalewidth}:{args.scaleheight},setsar=1:1[v{i}]")
    concat += f'[v{i}][{i}:a:0]'
concat += f'concat=n={len(args.infiles)}:v=1:a=1[outv][au]'
filterchain.append(concat)
filterchain.append(f'[au]{audiofilter}[outa]')

encodeargs.append("-filter_complex")
encodeargs.append(";".join(filterchain))

encodeargs += ['-map', '[outv]', '-map',  '[outa]']

encodeargs += [args.outfile]

print(encodeargs)

returncode = subprocess.call([command, *encodeargs])

if returncode:
    notify(f"Encoding failed with code {returncode}")
else:
    notify("Encoding success")