trialdef with bdf files

[Robert Oostenveld]

Hi Erin,

The DEFINETRIAL function is used to determine which segments of the
data are of interest. Only the segments of interest ("trials") are
read from the file and preprocessed using the PREPROCESING function.
In your case theer are trials defined for the cnt, but not for the
bdf file.

The preferred approach for using DEFINETRIAL is to supply it with
your own "trialfun" (cfg.trialfun=name_of_your_function, see the
documentation on the website). If you do not specify cfg.trialfun, a
default trialfun will be used. There are different defaults for the
different file formats. Your problem seems to be related to the
trialfun for neuroscan ctf having more appropriate defaults that the
trialfun for biosemi bdf.

I suggest that you explicitely write your own trialfun, using
read_fcdc_event. See
http://www2.ru.nl/fcdonders/fieldtrip/doku.php?
id=fieldtrip:documentation:tutorial:preprocessing#appendixdefining_your_
own_function_for_trial_selection
and
http://www2.ru.nl/fcdonders/fieldtrip/doku.php?
id=fieldtrip:documentation:examples:making_your_own_trialfun_for_conditi
onal_trial_definition

best regards,
Robert



On 24 Mar 2008, at 21:21, Erin Oakman wrote:
> hi,
>
> The filename of my data is 'vv(P)-gamma-aod_20.bdf'
>
> When using bdf files, and the trialdef function, I received this
> message.
>
>
>  process " vv(P)-gamma-aod_20.bdf " evaluating trialfunction
> 'trialfun_general'
> ??? Error using ==> definetrial at 193
> no trials were defined, see DEFINETRIAL for help
>
> If I read 'vv(P)-gamma-aod_20.cnt' files into the same script,
> there is no
> conflict.

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