cli: support "dummy" audio interface

specify '-' to to skip loading PortAudio shared library.

amodem-cli

@@ -94,6 +94,15 @@ def get_volume_cmd(args):
                 return c[args.command]
 
 
+class _DummyInterface(object):
+    ''' Audio interface mock, to skip shared library loading. '''
+    def __enter__(self):
+        pass
+
+    def __exit__(self, *args):
+        pass
+
+
 def _main():
     fmt = ('Audio OFDM MODEM: {0:.1f} kb/s ({1:d}-QAM x {2:d} carriers) '
            'Fs={3:.1f} kHz')
@@ -194,7 +203,12 @@ def _main():
         import pylab
         args.pylab = pylab
 
-    with interface.load(args.audio_library):
+    if args.audio_library == '-':
+        interface = _DummyInterface()
+    else:
+        interface.load(args.audio_library)
+
+    with interface:
         args.src = args.input_type(args.input)
         args.dst = args.output_type(args.output)
         try:

amodem/audio.py

@@ -17,7 +17,6 @@ class Interface(object):
         assert self._error_string(0) == b'Success'
         version = self.call('GetVersionText', restype=ctypes.c_char_p)
         log.info('%s loaded', version)
-        return self
 
     def _error_string(self, code):
         return self.call('GetErrorText', code, restype=ctypes.c_char_p)

tests/test_audio.py

@@ -15,7 +15,8 @@ def test():
         lib.Pa_OpenStream.return_value = 0
         cdll.return_value = lib
         interface = audio.Interface(config=config.fastest(), debug=True)
-        with interface.load(name='portaudio'):
+        interface.load(name='portaudio')
+        with interface:
             s = interface.player()
             assert s.params.device == 1
             s.stream = 1  # simulate non-zero output stream handle