import json
import subprocess
from typing import Optional


def get_stream_codec(stream_url: str) -> Optional[str]:
    result = subprocess.run(
        f'ffprobe -v error -select_streams v -show_entries stream=codec_name,width,height -of json "{stream_url}"',
        capture_output=True, text=True, cwd='.', shell=True)
    if result.returncode != 0:
        return None

    if result.returncode == 0:
        result_dict = json.loads(result.stdout)
        return result_dict['streams'][0]['codec_name'].lower()