LslReceiver

class gpype.backend.sources.lsl_receiver.LslReceiver

Bases: Source

Reads a Lab Streaming Layer stream into a pipeline.

The mirror of LSLSender, and the way another vendor’s amplifier, MATLAB, a stimulus program or a second g.Pype process gets its data in. Channel names, types and units are read from the stream description, so a g.Pype stream read back keeps what it was published with. Types and units are kept even where the channels are not all named; the names only where every channel has one.

What arrives this way is somebody else’s data: LSL carries no per-sample authentication, so a stream says what it is and cannot prove it.

RESOLVE_TIMEOUT_S = 5.0

How long to wait for the stream to appear, in seconds.

class Configuration

Bases: Configuration

Configuration class for LslReceiver parameters.

class Keys

Bases: Keys

Configuration keys for LslReceiver settings.

class OptionalKeys

Bases: OptionalKeys

Optional configuration keys.

STREAM_NAME = 'stream_name'

Stream name to resolve

STREAM_TYPE = 'stream_type'

Stream type to resolve, when no name is given

__init__(stream_name=None, stream_type=None, channel_count=None, sampling_rate=None, edge_id=None, **kwargs)

Initialize the receiver.

Parameters:

• stream_name (Optional[str]) – Name of the stream to resolve.

• stream_type (Optional[str]) – Type to resolve, when no name is given.

• channel_count (Optional[int]) – Expected channel count. Read from the stream when not given.

• sampling_rate (Optional[float]) – Expected rate. Read from the stream when not given.

• edge_id (Optional[str]) – Which edge runs this node, matched against the edge process’s –edge-id. None, the default, is every edge; ignored when the pipeline is not distributed.

• **kwargs – Additional arguments for the parent Source.

Raises:

• ValueError – If neither a name nor a type is given, or if the stream shape is missing on a server.

• RuntimeError – If the shape has to be read from a stream that does not appear.

setup(data, port_context_in)

Publish what the stream said about its channels.

Parameters:

• data (dict[str, ndarray]) – Initial data dictionary.

• port_context_in (dict[str, dict]) – Input port contexts.

Return type:

dict[str, dict]

Returns:

Output port contexts.

start()

Resolve the stream, open the inlet, and begin pulling.

This is where the publisher has to exist. Resolving here rather than in the constructor is what allows a saved pipeline to be rebuilt while the stream is offline.

Raises:

RuntimeError – If no matching stream appears in time.

stop()

Stop pulling and close the inlet.

step(data)

Emit the sample the pulling thread handed over.

Return type:

dict[str, ndarray]

Returns:

One sample, or None when nothing is waiting.