Downsampling with a processor

[bgrgic-inbrain]

Hi,

I am making a processor plugin that would downsample the samples from a buffer coming from a file source.
In updateSettings( ).

As I can't change the data stream's sampling rate, I create a new one and inject it with the previous one's metadata. Then replace the processor's data streams with the newly created one. Then in process after filtering I call setTimestampAndSamples with the new reduced buffer size. However there is always something missing and falls apart with the LFP viewer trying to digest the new stream in the signal chain.

I tried finding examples of something similar in other plugins but couldn't find anything. Would appreciate if you could guide me in the right direction.

Many thanks,
Bruno

• GUI version: [e.g. 1.0.2]
• OS: [e.g. Windows 11]
• Electrode type: [e.g. tetrodes, Neuropixels]

[jsiegle]

Hi Bruno – I'm not aware of any plugins that try to change the sample rate, so we don't have any examples. It sounds like you're going about things the right way, but it's hard to tell without looking at the code. Are you able to share a link to your plugin's source code?

Also, is it absolutely necessary to change the sample rate within the GUI's signal chain? If you're reading data from a file, it could be much easier to downsample the file offline.

[bgrgic-inbrain]

Hi @jsiegle ,

the idea is to use it online with different systems, as well as with a file reader.
Here is the source code of my attempt to get it running.

I tested it with FileSource -> Downsampler -> LFP Viewer. The graph looks good, but for some reason the buffer in process() comes with empty samples.

Here is the link to the source.

Many thanks,
Bruno