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Node properties

A Node has a number of read-only properties which can be used to query its status at a given moment in time.

Property Type Description
name str Short alphanumeric string that identifies the type of node (for example, asr-envelope)
num_output_channels int The number of output channels that the node generates.
num_input_channels int The number of input channels that the node takes. Note that most nodes have matches_input_channels set, meaning that their num_input_channels will be automatically increased according to their inputs. To learn more, see Nodes: Multichannel.
matches_input_channels bool Whether the node automatically increases its num_input_channels based on its inputs. To learn more, see Nodes: Multichannel.
has_variable_inputs bool Whether the node supports an arbitrary number of audio-rate inputs
output_buffer numpy.ndarray Contains the Node's most recent audio output, in float32 samples. The buffer is indexed by channel x frame, so to obtain the 32nd sample in the first channel, query: node.output_buffer[0][31].
inputs dict A dict containing all of the Node's audio-rate inputs. Note that buffer inputs are not currently included within this dict.
state int The Node's current playback state, which can be one of SIGNALFLOW_NODE_STATE_ACTIVE and SIGNALFLOW_NODE_STATE_STOPPED. The STOPPED state only applies to those nodes which have a finite duration (e.g. ASREnvelope, or BufferPlayer with looping disabled) and have reached the end of playback. Nodes continue to have a state of ACTIVE whether or not they are connected to the graph.
patch Patch Indicates the Patch that the node is part of, or None if the Node does not belong to a Patch.

Monitoring a node's output

To monitor the output of a node, call node.poll(num_seconds), where num_seconds is the interval between messages. This will print the last sample generated by the node to stdout. In the case of multichannel nodes, only the first channel's value is printed.

>>> a = Counter(Impulse(1))
>>> a.poll(1)
counter: 0.00000
counter: 1.00000
counter: 2.00000

To stop polling a node, call node.poll(0).

Node-specific properties

Some Node classes have additional properties, containing information on implementation-specific states. These can be accessed via the get_property method.

For example, the BufferPlayer node exposes a position property, which returns the playhead's current position, in seconds.

>>> buffer = Buffer("audio.wav")
>>> player = BufferPlayer(buffer)
>>> player.get_property("position")

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Last update: 2024-01-14
Created: 2022-04-01