Channel selection in acquisition server

  • NB: Document based on OpenViBE >= 0.18.0

With this feature we offer the user the possibility to select channels at the acquisition server level and thus only give the acquisition client the data it needs.

Let us consider a device that records EEG on 32 channels but we only need some of them. To use the channel selection we need to name only the channels we need. Usually, after naming those channels, we would have something like this :

all-channels-named

Name the channels you need and un-name the ones you do not in the drivers properties. You may only need to do this once and save this configuration in a txt file (save button) and load it when you need it (load button) :

name-channels

You should obtain (The acquisition server name ‘Channel index’ the channels that have no name) :

all-channels

To ask the acquisition server to only record the named channels, you need to set the corresponding checkbox in the preferences menu :

select-channels

Then you will see that only the named channels are displayed :

selected-channels

With this there is no need for a channel selector in the designer. See the following OpenViBE scenario for example :

scenario

In the usual case, with a channel selection done with the Channel Selector box the previous scenario would display :

signal-designer-level-selection

As you see the Acquisition client receives a lot of zeroes from the channels that do not record.
With the channel selection done at the acquisition server level, we would have :

signal-acquisition-level-selection

Only the relevant data is transferred.

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