Piping SoX in Python - subprocess alternative?
- by Cochise Ruhulessin
I use SoX in an application. The application uses it to apply various operations on audiofiles, such as trimming.
This works fine:
from subprocess import Popen, PIPE
kwargs = {'stdin': PIPE, 'stdout': PIPE, 'stderr': PIPE}
pipe = Popen(['sox','-t','mp3','-', 'test.mp3','trim','0','15'], **kwargs)
output, errors = pipe.communicate(input=open('test.mp3','rb').read())
if errors:
raise RuntimeError(errors)
This will cause problems on large files hower, since read() loads the complete file to memory; which is slow and may cause the pipes' buffer to overflow. A workaround exists:
from subprocess import Popen, PIPE
import tempfile
import uuid
import shutil
import os
kwargs = {'stdin': PIPE, 'stdout': PIPE, 'stderr': PIPE}
tmp = os.path.join(tempfile.gettempdir(), uuid.uuid1().hex + '.mp3')
pipe = Popen(['sox','test.mp3', tmp,'trim','0','15'], **kwargs)
output, errors = pipe.communicate()
if errors:
raise RuntimeError(errors)
shutil.copy2(tmp, 'test.mp3')
os.remove(tmp)
So the question stands as follows: Are there any alternatives to this approach, aside from writing a Python extension to the Sox C API?
