Fix callback handling and flag initialization

[IzaCarlos]

Problem

On Python 3.14, cffi changed how it passes arguments to native callbacks
and how it validates __init__ return values. This caused two distinct errors:

1. TypeError: __init__() should return None, not 'NoneType'
   cffi now intercepts and validates the return of __init__ at a lower
   level, causing it to spuriously reject the standard None return.

2. TypeError: unsupported operand type(s) for &: '_CDataBase' and 'int'
   The status argument now arrives as a raw _CDataBase object instead
   of a plain Python int, breaking bitwise operations in _hasflag.

Both errors surface in _wrap_callback and occur unpredictably during
stream callbacks, including during silence and active playback.

Fix

Bypass CallbackFlags.__init__ entirely in _wrap_callback using
__new__, then set _flags directly via int() cast. This avoids
the cffi __init__ interception and the _CDataBase bitwise issue
in one shot.

Changes

In _wrap_callback, replace:

args = args[:-1] + (CallbackFlags(args[-1]),)

With:

cf = CallbackFlags.__new__(CallbackFlags)
cf._flags = int(status)

Tested on

• Python 3.14.4, Sounddevice 0.5.5
• Extended idle periods (no audio) no longer trigger the error
• Active playback confirmed working after fix

[mgeier]

Thanks for this PR!

How can I reproduce the errors? Does this need a certain CFFI version?

[IzaCarlos]

How can I reproduce the errors? Does this need a certain CFFI version?

You can reproduce (I'm very sure) by installing Python v3.14.4 w/cffi 2.0.0 and Sounddevice with 0.5.5, then use any application that opens a stream for a long time.
Not to advertise or anything but one of my personal applications that monitors sound does use a continous stream and after being left idling it would eventually lead to this cffi error (pardon some mispells I had to OCR this since I couldn't copy paste from the box):

Exception ignored from cffi callback <function _StreamBase._init_.<locals>.callback_ptr at 0x000001DBC8B22140>:
Traceback (most recent call last):
File: "C:\Users\carlo\AppData\Local\Programs\Python\Python314\Li b\site-packages\sounddevice.py", line 862, in callback_ptr Exception ignored from cffi callback <function StreamBase. init <locals>.callback_ptr at 0x000001DBC8B22A30>:
Traceback (most recent call last):
File: "C:\Users\carlo\AppData\Local\Programs\Python\Python314\Lib\site-packages\sounddevice.py", line 878, in callback_ptr return_wrap_callback(callback, data, frames, time, status)
File: "C:\Users\carlo\AppData\Local\Programs\Python\Python314\Lib\site-packages\sounddevice.py", line 2775, in_wrap_callback return_wrap_callback(callback, data, frames, time, status)
File: "C:\Users\carlo\AppData\Local\Programs\Python\Python314\Li b\site-packages\sounddevice.py", line 2775, in_wrap_callback
args = tuple(args[:-1]) + (CallbackFlags(args[-1]),)
TypeError: __init__() should return None, not 'NoneType'

As mentioned I applied some fixes to my sd installation and it has not been causing any more issues.