[FieldTrip] Question about how to reduce the file size

Caspar, Emilie e.caspar at ucl.ac.uk
Fri Dec 12 23:24:17 CET 2014

Dear Fieltrippers,
I did a pilot study on one participant today. Now that I'm trying to analyze my data, I realize that the size file is too big for my computer (size = 3Gb). Even after one hour, the filters (high pass + low pass) were not yet achieved.

So I would like to see how to reduce the size of my sample BEFORE the filters.

I know that there is "ft_resampledata", and I did it to reduce the actual sample rate (= 2048) to 256. However, even with this procedure my computer is crashing (even with 16 Go RAM). In addition, I'm not sure that I can resample before filtering (I read different informations).

Another way I was thinking about was to pre-select electrodes that I need (only 6 electrodes on 64). But here I have two questions:
- Can I pre-process only some electrodes? Does it really reduce size for next preprocesses?
- Is this the correct way to ask? As it crashes, not sure it works.

    cfg             = [];
    cfg.dataset     = [ file.name];
    cfg.channel     = 'B5', 'B6', 'B15', 'B16';
    allData_prepross = ft_preprocessing(cfg);
    cfg.resamplefs = 256;
    DataSample = ft_resampledata(cfg, allData_prepross)

I would appreciate pieces of advice!

Many thanks :)


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