Importing files from PolyView (.bin)

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emat
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Importing files from PolyView (.bin)

Unread postby emat » 06 Aug 2019, 20:20

Hi - I'm attempting to reanalyze some old data sampled on a Grass PolyView system. The files are sampled at 1000Hz, and are about 1 hour in length. Grass PolyView .BIN files are an option in the Import menu in Spike2, but when I try to open the file, Spike2 crashes.

I can import the files as a binary file using the user input dialog, but I get weird results. The MaxTime of the imported file is the same, regardless of what I set in the file sampling rate. It always imports as 16629.7s long; we expect something in the range of 3600s. Following import, again regardless of what sampling rate is selected, the log window shows timing info as "Time Base (us): 1000". Additionally, the data is "sawtoothed".... see image below.

Does anyone have experience importing PolyView files into Spike? Any suggestions for why the binary import is going wrong?
Attachments
Import Binary.JPG
Grass PolyView .bin file imported into Spike2

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Tim Bergel
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Re: Importing files from PolyView (.bin)

Unread postby Tim Bergel » 09 Aug 2019, 16:28

"I can import the files as a binary file using the user input dialog, but I get weird results"

Just to check - what you mean here is that you cannot import as PolyView, but you can as 'raw' binary, is that correct?

Assuming it is, a raw binary file is assumed to be made up of a header, followed by data for a given number of channels interleaved together so that for a three channel file the data items would be arranged thus:

Channel 1, Channel 2, Channel 3, Channel 1, Channel 2, Channel 3 ...

You have to specify the header size correctly and set the number of channels to match what is present, and you also have to specify the sampling rate to match how the data was collected - as this is raw binary the importer cannot determine these values itself. So, it may be that you have not entered these values correctly (and it may also be the case that PolyView data is not structured in the correct manner). Looking at your picture, that waveform looks plausible but it appears to be made up of signals from multiple channels mixed together - so it may simply be that you have not entered the correct number of data channels.

You may want to experiment with getting the raw binary importer to work properly, but I imagine you would be much happier if you could use the PolyView importer as it will set up everything correctly. To do this you need an improved importer, one that does not fail. The first thing to do is to make sure you are running the latest release of your version of Spike2 - you can download a suitable update installer from the main CED web site.

If that does not work it may be that we have not found whatever fault in the importer is causing this. The first step is for you to reply to this post, telling me the exact version number of the copy of Spike2 that you are using. I will then be able to investigate and see if we appear to have fixed this, if not we may need a copy of your data file so that we can work on this.
Tim Bergel Cambridge Electronic Design

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Greg Smith
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Re: Importing files from PolyView (.bin)

Unread postby Greg Smith » 12 Aug 2019, 18:41

If you can send us the smallest file that does not import we can have a look at it to see if we can adjust the Grass importer to handle it. It may be that the file format has changed... any information you can give us about the version of the program that created the file would be helpful.
Greg Smith Cambridge Electronic Design

emat
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Re: Importing files from PolyView (.bin)

Unread postby emat » 12 Aug 2019, 20:37

Thanks for getting back to me, and sorry for the delayed response.

Tim - you are correct that I would prefer to just use the built in PolyView import, but if I need to parse the header to load it as a raw binary, I am willing to give it a try. The screen shot I uploaded resulted from importing as a raw binary file. I have played around with all of the importer settings in the binary importer, but consistently get the results you see. I agree that it looks "like" the expected waveform, but with extra points interpolated or something. There is only a single channel of data recorded, so I don't think it's summing across channels or anything like that.

I was using Spike2 version 9.04b, but just downloaded the latest upgrade, and it didn't solve the issue.

We have a very old version of PolyView16 - Version 1.1.

Greg - I have a smaller file than the 1hour long data that I was attempting to reanalyze. It's 8.3KB, so should be more easily transferred. But it looks like phpBB won't let me upload a .bin file as an attachment. Would you like me to send it via email or the CED website?


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