change the resoultion of a video on the fly

vidres.py

# Usage:
# python vidres.py path/to/input/video [path/to/output/video]

import os
import re
import shutil
import subprocess
import sys

data = subprocess.run(
    ["ffprobe", "-i", sys.argv[1]], capture_output=True, check=None
).stderr.decode()
h, m, s = map(float, re.findall(r"\d\d:\d\d:\d\d\.\d\d", data)[0].split(":"))
width, height = map(
    int, re.findall(r"\d+x\d+", re.findall(r"Stream.*\)", data)[0])[-1].split("x")
)

try:
    os.mkdir("temp")
    OUT_FILE = sys.argv[2]
except (FileExistsError, IndexError):
    OUT_FILE = "output.webm"

# split clips
count = 0
for hours in range(int(h + 1)):
    for minuites in range(int(m + 1)):
        for seconds in range(int(s + 1)):
            for splitseconds in range(0, 100, 10):
                subprocess.run(
                    [
                        "ffmpeg",
                        "-y",
                        "-ss",
                        str(hours).rjust(2, "0")
                        + ":"
                        + str(minuites).rjust(2, "0")
                        + ":"
                        + str(seconds).rjust(2, "0")
                        + "."
                        + str(splitseconds).rjust(2, "0"),
                        "-t",
                        "00:00:00.10",
                        "-i",
                        sys.argv[1],
                        "-c:a",
                        "copy",
                        f"temp/.{count}.mp4",
                    ],
                    check=None,
                )
                count += 1
## `count` is the total number of clips that were split from the original video

# scale clips
for _ in range(count - 10): # skip the last second
# why (count - 10)? cuz we split the clip into secions of `10`/100 seconds each
    subprocess.run(
        [
            "ffmpeg",
            "-y",
            "-i",
            f"temp/.{_}.mp4",
            "-vf",
            f"scale={width}:{height}",
            f"temp/_{_}.webm",
        ],
        check=None,
    )
    ## Do all your frame manipulation here
    if _ // max(1, count // 14) % 2 != 0: # (count//n), `n` is (roughly) how many times the effect alternates
        height += 200 # use whatever that works best for you
    else:
        height -= 200


# speed up clips
with open("src.txt", mode="w", encoding="utf-8") as f:
    for index in range(count - 10):
        subprocess.run(
            [
                "ffmpeg",
                "-y",
                "-i",
                f"temp/_{index}.webm",
                "-filter:v",
                f"setpts=PTS/{10e50}",
                f"temp/{index}.webm",
            ],
            check=None,
        )
        f.write(f"file 'temp/{index}.webm'\n")


# concat clips
subprocess.run(
    [
        "ffmpeg",
        "-y",
        "-f",
        "concat",
        "-safe",
        "0",
        "-i",
        "src.txt",
        "-c",
        "copy",
        "-an",  # mutes audio
        OUT_FILE,
    ],
    stderr=subprocess.DEVNULL,
    check=None,
)

# clean stuff up
shutil.rmtree("temp")
os.remove("src.txt")

# Then you can use something like this to add in audio
# ffmpeg -i video.webm -i audio.wav -map 0:v -map 1:a -c:v copy -shortest out.webm
# The `-shortest` option will make the output the same duration as the shortest input