File Reader additional capabilities

[ChucklesOnGitHub]

The File Reader+LFP viewer is excellent for researchers looking to inspect their data quickly after experiments without the need for code. I was talking to a reasearcher in the MMC course that uses the GUI to quickly look through emg files after recordings for looking at interesting segments. They can quickly pause the viewer and go back a few seconds to inspect a particular epoch in more detail. However, they have more specific needs that could perhaps be incorporated for everyone.

• looking at data shorter than 30 sec (their behavior is super short so trials are just a few sec long).
• scale channels individually since some have big spikes and others small (maybe autoscale to max to make it easy) - this is LFPViewer related but it came up in this context
• finding segments of interest is not super intuitive because the file reader scrubbing doesn't move the visual display, since, instead, you have to use it as an acquisition source, start acquisition and wait for playback to see signals on the screen. We worked around this using Pause on the LFP viewer to be able to go back and look at a segment of interest but that doesn't relate back to the File Reader scrubber. Maybe the viewer can mark when Pause was pressed so as to get the timestamp of the interesting segment and then go and look for it with the reader.
• ability to change the timebase while paused - currently you cannot "zoom in" unless you change the timebase and run the segment again.

Perhaps this usage of the GUI is at the limit of what can be done with a recorded file as a data source vs an application designed as a data viewer. Do any such apps exist? (A broader need here is to quickly visualize camera frames in sync with the ephys, using the recorded TTL signals).

[jsiegle]

Thanks for this feedback! I definitely agree that having the LFP Viewer locked to the File Reader scrubber would be the easiest way to browse data offline. The best way to do this would be to integrate a simple visualizer into the File Reader itself, which would be a big project.

It would also be helpful to be able to zoom in on segments while the display is paused. This would require a major overhaul of how the LFP Viewer currently works. Right now, it copies all incoming data into a "screen buffer," downsampling it in the process. For example, if the timebase for a 30 kHz data stream is 2 seconds long, but the display is only 1000 pixels wide, it will take 2 s * 30,000 Hz = 60,000 incoming samples and compress it down to a min, max, and mean value for 3000 pixels (to allow the display to be scrolled backwards when paused). To make it possible to change the timebase, the LFP Viewer would also have to store the full sample rate data for the whole length of the display. This is probably doable, but not something that we'll be able to implement in the near future.

As of the official v1.0 release, the scrubbing functionality works with data files of any size (including very short ones).

To visualize channels with different optimal ranges, would it work to split the LFP Viewer vertically, and set a different range value for each side? Disabling a subset of channels on one side would prevent channels with large spikes from overwhelming the ones with small spikes.