How can I pass data in python without the cat command?

Question

I have the following working code in first.py

import os os.system('cat python_better_than_java.wav') 

which I can execute this way

 python first.py | ffmpeg -y -f wav -i pipe:0 -f mp3 - >hi.mp3 

it works.

I want to do this with pythonic, so I edited first.py :

 import sys with open('python_better_than_java.wav', 'rb') as content_file: content = content_file.read() sys.stdout.write(content) 

and executed it using:

 python first.py | ffmpeg -y -f wav -i pipe:0 -f mp3 - >hi.mp3 

but then it raises the following error:

 pipe:0: Invalid data found when processing input 

How can i play cat in python?