[Mne_analysis] mne_brain_vision2fiff Losing Events?

[Alexandre Gramfort]

Christian,

do you know which events are missed?

do you see the stim channel rising from 0 at these time points?

@matti : any idea what may be happening?

Best,
Alex

On Fri, Aug 17, 2012 at 2:25 PM, Alexandre Gramfort
<gramfort at nmr.mgh.harvard.edu> wrote:
> hi Christian,
>
> I confirm that I find 1958 events in your file with both
> mne_process_raw and mne-python
>
> $mne_brain_vision2fiff --header R0458_eref3h.vhdr --out test.fif
>
> indeed reports 1960 events although with
>
> $mne_process_raw --raw test_raw.fif --events test-eve.fif
>
> and loading test-eve.fif in Python I get only 1958
>
>>>> import mne
>>>> ev = mne.read_events('test_raw-eve.fif')
>>>> len(ev[ev[:, 2] == 128])
> 1958
>
> I therefore suspect an issue in the C code maybe while writing the
> stim channel to fif.
>
> We'll have to dig in the C code and maybe Matti can give us a hand.
>
> Alex
>
> On Wed, Aug 15, 2012 at 6:50 PM, Christian Brodbeck <cmb650 at nyu.edu> wrote:
>> Hello,
>>
>> When converting with mne_brain_vision2fiff, the resulting fif files seem to be missing events on occasion. My recordings should all contain 1960 events. mne_brain_vision2fiff says "nevent = 1960" (for the complete output see below), however, when opening the resulting fiff files in mne-python, up to 3 events are missing. The conversion seems to lose events consistently (i.e. when I repeat the command the same number of events get lost):
>>
>> n events found by mne-python for my different subjects:
>> 1959   R0040_eref3h_raw.fif
>> 1958   R0458_eref3h_raw.fif
>> 1957   R0425_eref3h_raw.fif
>> 1957   R0355_eref3h_raw.fif
>> 1960   R0273_eref3h_raw.fif
>> 1960   R0541_eref3h_raw.fif
>>
>> The event channel data reflects that (for a recording with 1958 events):
>>
>>>>> np.unique(data)
>> array([   0.,  128.])
>>>>> np.sum(np.diff(data) > 0)
>> 1958
>>>>> np.sum(np.diff(data) < 0)
>> 1958
>>
>> I also tried the nightly version of mne with the same result. In case someone can have a look, I uploaded a set of files (10 mb): https://dl.dropbox.com/u/659990/R0458%20eref3h.zip
>>
>> Thanks
>>
>> Christian
>>
>>
>>
>>
>>
>>
>>
>> $ mne_brain_vision2fiff --header R0458_eref3h.vhdr --out R0458_eref3h.fif
>>
>> mne_brain_vision2fiff version 1.7 compiled at Jan  7 2011 02:26:21
>>
>> header  file           : R0458_eref3h.vhdr
>> output file            : R0458_eref3h.fif
>>
>> Read header file : R0458_eref3h.vhdr
>> Read header file : R0458_eref3h.vmrk
>>
>> nchan           = 5
>> sfreq           = 500.0  Hz
>> raw data file   = R0458_eref3h.eeg
>> raw binary      = true
>> raw binary type = 16
>> raw endian      = little
>> raw nsamp       = -1
>> nevent          = 1960
>> eXimia          = false
>>
>> Data will be split into <= 1907.3 MByte pieces
>>
>> Writing header to R0458_eref3h_raw.fif ... [done]
>> Writing raw data to R0458_eref3h_raw.fif ... Number of samples deduced from the raw file size : 671230
>> [done]
>> Wrote 1...671230 of 671230 samples total to R0458_eref3h_raw.fif
>> Adding directory to R0458_eref3h_raw.fif...[done]
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