[FieldTrip] Unsupported data format

Nakyung Lee rleese12 at berkeley.edu
Fri Jul 15 08:49:41 CEST 2016

Hi Arjen,

Thank you for your reply.
Your email got forwarded successfully.

So currently I tried using 'ft_definetrial' and 'ft_preprocessing'.
'ft_definetrial' returns an error when used with 'ft_trialfun' set to
Below is the code I used (and 'signal_raw.mat' is a fieldtrip raw data and
it has all three fields you mentioned).

cfg.dataset = 'signal_raw.mat';
cfg.trialdef.event = subj_globals.buttonpress_times;
cfg = ft_definetrial(cfg);

So I simply call ft_definetrial with minimal configuration and here's the
error I got:

Error using ft_read_header (line 2194)
unsupported header format "matlab"

Error in ft_trialfun_general (line 78)
hdr = ft_read_header(cfg.headerfile, 'headerformat', cfg.headerformat);

Error in ft_definetrial (line 177)
    [trl, event] = feval(cfg.trialfun, cfg);

Error in trialdef_alsotest (line 12)
cfg = ft_definetrial(cfg);

I circumvented this issue by using my own trialfun ('ft_trialfun_test' in
the code).
We already have all the necessary timestamps so I could build a very simple
Here's a new code (I ran the code with minimal cfg for 'ft_preprocessing'
to isolate the problem):

cfg.dataset = 'signal_raw.mat';
cfg.trialfun = 'ft_trialfun_test';
cfg.trialdef.event = subj_globals.buttonpress_times;

cfg = ft_definetrial(cfg);

cfg.continuous = 'yes';
buttonpress_hg = ft_preprocessing(cfg);

And here's the error I got:

Error using ft_read_header (line 2194)
unsupported header format "matlab"

Error in ft_preprocessing (line 397)
  hdr = ft_read_header(cfg.headerfile, 'headerformat', cfg.headerformat,
'coordsys', cfg.coordsys, 'coilaccuracy',

Error in test_trialdef (line 18)
buttonpress_hg = ft_preprocessing(cfg);

So both error come from 'ft_read_header'.
I've been looking at the code but it seemed quite hard to debug as
'ft_read_header' uses a lower level function that directly reads from the
file (hence it seemed like a simple fix like passing in a fake header
wouldn't work).
Am I doing something wrong here?

Again, thank you for your reply and let me know if you need more


On Thu, Jul 14, 2016 at 12:10 AM, Arjen Stolk <a.stolk8 at gmail.com> wrote:

> Hi Rachel,
> What is the error you're receiving, and how are you calling
> ft_preprocessing?
> If the data is in raw format (incl a trial, time and label field), it
> should theoretically be possible to use ft_preprocessing on it, eg;
> cfg = []
> cfg ..
> data = ft_preprocessing(cfg, raw)
> where raw is your data as described above.
> Best,
> Arjen
> > On Jul 13, 2016, at 11:50 PM, Nakyung Lee <rleese12 at berkeley.edu> wrote:
> >
> > Dear FieldTrip community,
> >
> > My name is Rachel Lee and I'm a research assistant in Prof. Ming Hsu's
> lab in UC Berkeley.
> >
> > We currently have a .Tbk file, a .Tdx file, .tev file, .tsq file to
> preprocess and analyze but it seems like those data formats are not yet
> supported by FieldTrip.
> > So, instead of using those raw data files, we've been trying to find a
> workaround by transforming them into a .mat file (and casting the .mat file
> into a raw datatype in FieldTrip by manually assigning fields to it).
> > This hasn't been so successful; we've been unable to call
> ft_preprocessing because of the lack of a proper header format (which is
> needed in ft_read_header, one of the lower level functions that
> ft_preprocessing calls).
> > I've been looking at the codes but been unable to come up with a
> solution.
> >
> > Does anyone have a similar experience?
> > Is there any way to circumvent this issue?
> > Any type of help would be appreciated.
> >
> > Thank you,
> > Rachel Lee
> > _______________________________________________
> > fieldtrip mailing list
> > fieldtrip at donders.ru.nl
> > https://mailman.science.ru.nl/mailman/listinfo/fieldtrip
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