Using FFmpeg to read input via stdin in Python

ffmpeg_stdin.py

# pip install pytube3
import pytube

import urllib.request
import subprocess

content = pytube.YouTube("https://www.youtube.com/watch?v=YQHsXMglC9A")
streams = content.streams.filter(only_audio=True).order_by("abr").desc()
response = urllib.request.urlopen(streams[0].url)

def download_and_convert_sequentially():
    with open("input.opus", "wb") as fout:
        fout.write(response.read())

    command = ("ffmpeg", "-y", "-i", "input.opus", "output.wav")
    process = subprocess.Popen(command)
    process.wait()


def download_and_convert_parallely():
    command = ("ffmpeg", "-y", "-i", "-", "output.wav")
    process = subprocess.Popen(command, stdin=subprocess.PIPE)

    while True:
        chunk = response.read(16 * 1024)
        if not chunk:
            break
        process.stdin.write(chunk)

    process.stdin.close()
    process.wait()


# download_and_convert_sequentially()
download_and_convert_parallely()

I've been looking for download_and_convert_parallely() all day, thank you!
I was originally using the ffmpeg-python library's run_async() function, trying to do a similar process.stdin.write(chunk) but the pipe closed after the first call to stdin.write, I think their implementation is specific to "pipe:" input.