2019-07-15: Lab Streaming Layer (LSL) Tutorial for Windows

First of all, I would like to give credit to Matt Gray for going through the major hassle in figuring out the prerequisites and for the awesome documentation provided on how to Install and Use Lab Streaming Layer on Windows.
LSL is low-level technology for exchange of time series between programs and computers.



Now, that the LSL installation is complete, we will have a look at the LabRecorder. Labrecorder is the main LSL program to interact with all the streams. You can find the LabRecorder program at C:\labstreaminglayer\install\LabRecorder\ LabRecorder.exe.

The interface of LabRecorder  looks like following.

Figure: LabRecorder interface when PupilLabs is streaming

Installing PupilLabs LSL connection: There are many devices which could be connected with LSL. Muse EEG device, Emotive Epoc EEG device, and PupiLabs core eye tracker are some of them. The example below shows how to use PupilLabs core eye tracker with LSL for streaming data to NeuroPype.

Connect PupilLabs with LSL: Build liblsl-Python in a Python or Anaconda Prompt. You could do with your command prompt as well. Execute following commands:
1. cd C:\labstreaminglayer\LSL\liblsl-Python
2. python setup.py build

Then, you have to install LSL as plugin in Pupil Capture program. 

Figure: Original Location of  pupil_lsl_relay.py

Figure: After copying pupil_lsl_relay.py and pylsl folder into C:\Users\<user_profile>\pupil_capture_settings\plugins folder

If the pylsl folder does not have lib folder containing liblsl64.dll, there is a problem with pylsl build. As an alternative approach, install pylsl via pip by runningpip3 install pylslcommand in command prompt. Make sure you have installed pip in your computer prior running these commands in your command prompt. You can use pip3 show pylslcommand to see where is the pylsl module built in your compute. This module will include the pre-built library files. Copy this newly created pylsl module to the C:\Users\<user_profile>\pupil_capture_settings\pluginsfolder. 
In this example,  pylsl module  was installed in C:\Users\<user_profile>\AppData\Local\Python\Python37\Lib\site-packages\pylsl folder. It includes a lib folder which contains 

Figure: pylsl module's installation location when used pip3 install pylsl command

As the next step, launch pupil_capture.exe and enable Pupil LSL Relay from Plugin manager in Pupil Capture – World window.

Figure: Enabled Pupil LSL Realy from Plugin Manager

Now when you hit the R button on the left of World window, you start recording from PupilLabs while streaming it to the LSL.  In Labrecorder, you could see the streams in green color (see Figure LabRecorder interface when PupilLabs is streaming).
Now, let's have a look at how to get data from LSL to Neuropype.

Getting Started with Neuropype and Pipeline Designer:


Create an Example Pipeline: Select LSL Input node in Network (green) section, Dejitter Timestamp in Utilities section (light blue), Assign Channel Locations in Source Localization section (Pink), Print To Console in Diagnostics section (pink) from widget panel.

Figure: Pipeline created in Neuropype

Figure: Set up type of LSL Input