timelapse-2.py

import subprocess
import os
import sys
import shutil

SEC_LENGTH = 30  # section length - actual time (s)
SEC_SEP = 120  # time petween sections - actual time (s)
SPEEDUP = 1
FPS_FINAL = 15
PART_LENGTH = 59  # time - output time (s)

DIR_TMP = "tmp"
DIR_CLIPS = os.path.join(DIR_TMP, "clips")
DIR_OUT = "output"
DIR_INP = "input"

def run(cmd):
    print("> "+str(cmd))
    subprocess.run(cmd, shell=True)

def run_out(command):
    print("> " + str(command))
    result = subprocess.run(command, stdout=subprocess.PIPE, shell=True)
    output = result.stdout.decode('utf-8').rstrip()
    print("= " + str(output))
    return output

def ffmpeg(params):
    run("ffmpeg -nostdin -y -hide_banner {}".format(params))

def concat(video_paths, output):
    run("mkvmerge -o {} {}".format(
        output,
        " +".join(['"' + str(x) + '"' for x in video_paths])
    ))

def clip(input_path, start, duration, output_path):
    ffmpeg("-ss {1} -i \"{0}\" -t {2} \"{3}\"".format(
        input_path,
        start,
        duration,
        output_path
    ))

def del_temp():
    if os.path.exists(DIR_TMP) and os.path.isdir(DIR_TMP):
        shutil.rmtree(DIR_TMP)

def get_length(path):
    # https://superuser.com/a/945604/581663
    return float(run_out("ffprobe -v error -show_entries "
                         "format=duration -of default=noprint_wrappers=1:nokey=1 \"{}\""
                         .format(path)))

del_temp()
os.makedirs(DIR_TMP)
os.makedirs(DIR_OUT, exist_ok=True)

input_files = []
for file_name in os.listdir(DIR_INP):
    input_files.append(os.path.join(DIR_INP, file_name))

merged_file = os.path.join(DIR_TMP, "merged.mkv")
concat(input_files, merged_file)
merged_length = get_length(merged_file)

# split videos
os.makedirs(DIR_CLIPS, exist_ok=True)

clip_no = 0
cur_time = 0
while cur_time < merged_length:
    clip(merged_file, cur_time, SEC_LENGTH, os.path.join(DIR_CLIPS, "{:05d}.mkv".format(clip_no)))
    cur_time += SEC_LENGTH + SEC_SEP
    clip_no += 1

# merge videos into timelapsed file
timelapsed_file = os.path.join(DIR_TMP, "timelapsed.mkv")
concat([
    os.path.join(DIR_CLIPS, "{:05d}.mkv".format(i)) for i in range(clip_no)
], timelapsed_file)

out_file = os.path.join(DIR_OUT, "output.mkv")
ffmpeg("-r {0} -i \"{1}\" -an -vf \"setpts=PTS/{0}\" \"{2}\"".format(FPS_FINAL, timelapsed_file, out_file))