[Mne_analysis] "mne_process_raw" vs "mne_raw2mat" sample # mismatch

[Matti Hamalainen]

On Aug 8, 2011, at 2:04 PM, Alexandre Gramfort wrote:

> Hi Matt,
> 
> glad this solved the pb. The current choice makes the content of event files
> and the output of mne_raw2mat consistent which is I feel a good behavior.

Hi Matt,

An additional comment: Why do you go to the trouble of using mne_raw2mat at all? You can read the raw data quite efficiently with the MNE matlab routines directly without the conversion and wasted disk space.

Incidentally, the first line in the (text) event file also tells you the offset you need to subtract from the event sample numbers to get to the sample numbers in mne_raw2mat output. 

- Matti


> 
> Alex
> 
> On Mon, Aug 8, 2011 at 2:00 PM, Matt Panichello
> <panichem at nmr.mgh.harvard.edu> wrote:
>> Hi Alex,
>> data.first_sample does equal the mismatch; this means that the difference in
>> sample numbering is due to whether or not the "initial skip" is taken into
>> account, correct? Are there any flags which allow mne_fiff2mat be modified
>> so that it doesn't exclude this initial skip? (I didn't see anything in the
>> help.)
>> If not, I can just use the data.first_sample value to convert between the
>> two numberings as needed.
>> Thanks a lot,
>> Matt
>> 
>> On Fri, Aug 5, 2011 at 10:01 PM, Alexandre Gramfort
>> <gramfort at nmr.mgh.harvard.edu> wrote:
>>> 
>>> Hi Matt,
>>> 
>>> can you run fiff_setup_read_raw on the raw data and look if the #
>>> mismatch is equal to the first_samp in the output structure ?
>>> 
>>> data = fiff_setup_read_raw('data_raw.fif')
>>> data.first_samp
>>> 
>>> Alex
>>> 
>>> On Fri, Aug 5, 2011 at 3:44 PM, Matt Panichello
>>> <panichem at nmr.mgh.harvard.edu> wrote:
>>>> Hello,
>>>> I am reading raw data into matlab using mne_raw2mat. For the files I
>>>> have
>>>> read in, I have noticed a mismatch between the sample numbering in the
>>>> resulting matlab structure and the sample numbering in the event file
>>>> produced mne_browse_raw.
>>>> For example, a particular trigger value (3) first appears at column
>>>> number
>>>> 64,016 in my MNE_raw.data structure in the STI 14 row, while it is
>>>> listed at
>>>> sample 72,415 in the event file produced by mne_browse_raw.
>>>> 
>>>> Does anyone have any idea what the source of the sample # mismatch could
>>>> be?
>>>> I tried manipulating the "keep initial skip" option in mne_browse_raw
>>>> but
>>>> this didn't seem to make any difference in the event file output.
>>>> Thanks,
>>>> Matt
>>>> 
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>>> 
>>> 
>> 
>> 
>> 
>> --
>> Matthew Panichello
>> Research Coordinator, Cognitive Neuroscience Laboratory
>> Massachusetts General Hospital
>> Phone: 617-726-0308
>> 
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