command working with cmd but not from python code

Question

I am trying to convert a test.mp4 file to test.wav from python code using avconv. I am able to convert the test.mp4 to test.wmv using cmd line but when i run the same command from python its giving me following error :

line 103, in get_message_audio subprocess.call(cmdline) FileNotFoundError: [WinError 2] The system cannot find the file specified

The code i am using from python file is :

cmdline = ['avconv', '-i', 'test.mp4', '-vn', '-f', 'wav', 'test.wav']

subprocess.call(cmdline)

But when i run the same command from cmd it successfully runs and save the test.wav file.

cmd line = avconv -i test.mp4 -f wav test.wav

Note: I have added avconv to system variable. The python file and test.mp4 is in the same directory. I am running the cmd from the same directory as well.

Answer 1

My guess is that it is not finding the avconv executable. I would suggest that you use the full absolute path to avconv in your command in Python. Another thing you can try is using a shell, by adding shell=True to your subprocess.call() call.

In other words, do this and see if it helps:

cmdline = [r'\full\path\to\avconv', '-i', 'test.mp4', '-vn', '-f', 'wav', 'test.wav']
subprocess.call(cmdline, shell=True)

I don't think it's the input file it can't find. It doesn't seem to be getting that far. At the point that subprocess.call(cmdline) is failing, test.mp4 and test.wav are just strings being passed to avconv.

My guess is that avconv isn't in the PATH of the environment in which Python is running the command. shell=True might help that.

Answer 2

Probably the location of the file is not your current working directory. Add

import os

print(os.getcwd())

To check where your script looks for the files.

If that’s not the right location, you can use

os.chdir(„your/file/directory“)