[FieldTrip] What exactly does filterpadding do?

[Brehm, J. (Julia)]

Dear list,

I am having problems applying filterpadding when using ft_artifact_zvalue.

Could someone please explain what exactly the effect of filterpadding is, and in which cases I can apply it and in which not?

I intended to use it to avoid edge effects in the artifact detection. However, I get the following warning (only when applying fltpadding, my data does not actually contain NaNs):

Warning: data contains NaNs, no filtering or preprocessing applied
> In ft_warning (line 181)
  In preproc (line 282)
  In ft_artifact_zvalue (line 292)

These are my settings:
cfg            = [];
cfg.trl        = temptrl; % all trials

cfg.artfctdef.zvalue.channel     = channel{ch};  % single channel
cfg.artfctdef.zvalue.cutoff      = 3;
cfg.artfctdef.zvalue.fltpadding  = 0.1;

cfg.artfctdef.zvalue.bpfilter   = 'yes';
cfg.artfctdef.zvalue.bpfilttype = 'but';
cfg.artfctdef.zvalue.bpfreq     = [1 3];
cfg.artfctdef.zvalue.bpfiltord  = 2;
cfg.artfctdef.zvalue.hilbert    = 'yes';

Thanks!

Best,
Julia
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