[Python-3000] audio device support

[Lars Immisch]

Hi,

I recently worked on Python audio device support for Linux and OS X. Not 
so recently, I wrote a DirectSound module for win32.

Python 2 has support for various audio devices, but they have no common 
interface and some are broken or obsolete. Python 3000 might be a chance 
to improve on this.

The situation seems to be:

Linux:

ossaudiodev is becoming obsolete on Linux (because OSS is being replaced 
by ALSA).

pyalsaaudio, http://sourceforge.net/projects/pyalsaaudio, is broken for 
multithreaded programs: it does not wrap blocking calls with 
Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS. A suitable, submitted patch 
has not been included by the maintainer in nearly two years. With this 
or a similar patch, it works fine, however.

Windows:

win32all has DirectSound support, but it's lowlevel and complicated. 
Other audio device wrappers may exit, but I don't know about them.

OS X:

The (undocumented) audiodev implementation does not work for me. There 
is a pyrex implementation for coreaudio support which I haven't tested, 
but I have written coreaudio wrappers in C (to be published).

What I'd like to see:

I like the idea of having audio device support for the major operating 
systems in the standard library.

But I am even more interested in a common interface for simple operations.

IMO, the API should support:

- stereo playback
- stereo recording
- different sampling rates and formats (alaw, mulaw and PCM in signed 
integers in various widths and maybe PCM in floats/doubles).
- device selection
- volume control

Overall, I think the level of abstraction in the OSS or ALSA APIs is 
about right, coreaudio on OS X and DirectSound on Windows are overkill 
outside of niche applications.

I would volunteer sample implementations for Windows, OS X and Linux (ALSA).

- Lars