Error when using ffmpeg via subprocess in python?

Question

Python

Hello, in this code:

import os
import subprocess

file = "Имя файла"
os.chdir("Путь до файла")
subprocess.call("ffmpeg -loop 1 -i {}.jpg -i {}.mp3 -c:v libx264 -c:a aac -movflags +faststart -shortest {}.mp4".format(file), shell=True)

This error occurs:
subprocess.call("ffmpeg -loop 1 -i {}.jpg -i {}.mp3 -c:v libx264 -c:a aac -movflags +faststart -shortest {}.mp4".format(a ), shell=True)
IndexError: Replacement index 1 out of range for positional args tuple

Answer 1

For each {} in format there must be a value.