API docs for “aculab.switching.Path”

Path objects can be used for mixing, echo cancellation, automatic gain control and pitch shifting.

Logging: Path names are prefixed with pt- and the log name is switch.

Method	__init__	Allocate a Path for signal transformation.
Method	close	Close the path.
Method	__del__	Undocumented
Method	listen_to	Listen to a timeslot or a tx instance.
Method	get_datafeed	Get the datafeed. Part of the switching protocol.
Method	echocancel	Cancel the echo from the input.
Method	stop_echocancel	Stop echo cancellation.
Method	agc	Configure automatic gain control and fixed volume adjustments.
Method	pitchshift	Configure pitch shifting on a signal.
Method	mix	Mix with another signal. The signal from mixin is added to the
Method	stop_mix	Stop mixing.
Method	get_status	Get the status of the path.

def __init__(self, card, module, ts_type=lowlevel.kSMTimeslotTypeALaw): (source)

Allocate a Path for signal transformation.

Parameters	card	a `snapshot.Card` instance.
	module	a `snapshot.Module` instance.
	ts_type	default is `kSMTimeslotTypeALaw` Related Aculab documentation: sm_config_module_switching.

def close(self): (source)

Close the path.

Related Aculab documentation: sm_path_destroy.

def __del__(self): (source)

Undocumented

def listen_to(self, source, tdm=None): (source)

Listen to a timeslot or a tx instance.

Parameters source a tuple (stream, timeslot, [timeslot_type]) or a transmitter instance (VMPtx, FMPtx or TDMtx), which must be on the same module.

tdm

Used internally.

Applications should normally use switching.connect.

Related Aculab documentation: sm_path_datafeed_connect.

def get_datafeed(self): (source)

Get the datafeed. Part of the switching protocol.

def echocancel(self, reference, nonlinear=False, use_agc=False, fix_agc=False, span=0): (source)

Cancel the echo from the input.

Parameters	reference	The reference signal. Can be anything with a `get_datafeed` method, like a `SpeechChannel`, a `VMPrx` or a `TDMrx`.
	nonlinear	enable/disable non-linear processing.
	use_agc	enable/disable automatic gain control on the input signal.
	fix_agc: enable/disable fixed gain. Related Aculab documentation: sm_path_echocancel.

def stop_echocancel(self): (source)

Stop echo cancellation.

Related Aculab documentation: sm_path_echocancel.

def agc(self, agc=True, volume=0): (source)

Configure automatic gain control and fixed volume adjustments.

Parameters agc enable automatic gain control.

volume

The volume in dB, in the range from -24 to 8.

The fixed volume adjustment is done after automatic gain control.

Related Aculab documentation: sm_path_agc.

def pitchshift(self, shift=0.0): (source)

Configure pitch shifting on a signal.

param shift: Pitch shift in octaves. Values higher than 1 cause an upward shift, values lower than 0.0 cause a downward shift.

Example: to pitch down a semitone, use -0.08333 (-1/12).

Related Aculab documentation: sm_path_pitchshift.

def mix(self, mixin, volume=-6): (source)

Mix with another signal. The signal from mixin is added to the signal processed by this path, and the result is adjusted accorded to the volume.

Parameters	mixin	the signal to mix in. Anything with a `get_datafeed` method, like a `SpeechChannel`, a `VMPrx` or a `TDMrx`. These must be on the same module.
	volume	Volume adjustment in dB. The default is -6, which prevents the resulting signal from being louder than the original. Related Aculab documentation: sm_path_mix.

Class a.s.Path(object):