[visionegg] Re: Fwd: M-sequences and timing

From: acp1@xxxxxxxxxxxxxxxxx
To: timblanche@xxxxxxxxxxx, visionegg@xxxxxxxxxxxxx
Date: Thu, 9 Aug 2007 15:14:05 -0700

Thank you so very much, Tim!  We really appreciate the help and the .py files
are great.  I am sorry to say that we ran into a wall, though.  While most the
.py files run fine on our computer, we cannot get makemseqmovie.py to run.  We
get the below error.

import Numeric, array, Dimstim.extMseqC, struct

error:
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in -toplevel-
    import Numeric, array, Dimstim.extMseqC, struct
ImportError: DLL load failed: The specified module could not be found.

Is there some special path that we need to specify?  (I already added the
PYTHONPATH to your system environment in Windows).

Also, is there some way we can use our own generated m-sequence images?

Thank you very much!
Angelique

Begin forwarded message:

From: "Tim Blanche" <timblanche@xxxxxxxxxxx>
Date: August 8, 2007 6:36:22 PM MST
To: visionegg@xxxxxxxxxxxxx
Cc: phillipj@xxxxxxxxxxxxxxxxx
Subject: Re: [visionegg] M-sequences and timing

Hi Angelique,

Martin Spacek and I managed to get movies, including m-sequence
checkerboards, running reliably at 200Hz (on an Iiyama Pro 454 screen,
hard to come by these days).  Check out the link to "dimstim" in the
News & Announcments sidebar of the Swindale lab home-page
(swindale.ecc.ubc.ca).  It has code and examples on how to do generate
high frame rate movies in Vision Egg.

Good luck,

Tim.

On Wed,  8 Aug 2007 18:16:08 -0700, "Angelique"
<acp1@xxxxxxxxxxxxxxxxx> said:

Hello, Vision Egg masters,

I have two questions regarding Vision Egg and timing.  I would  greatly
appreciate any help you could offer.

First, Iseem to be having trouble with the timing of basic flicker
stimuli.  The duration of the stimulus should be 100 ms, but I find
that the photodiode is showing the duration of the stimulus is at
around 150 ms.  Is there a particularly stupid thing I am doing to  get
this discrepancy?

Second, I am trying to put together an m-sequence stimulus set to  test
receptive fields of individual cells in the fly brain.  I generated a
set of m-sequences (1000 frames) in Matlab and converted this
information into .txt files. Then, I have Vision Egg load these files
one by one and reproduce the m-sequence in order.  Now, because it's
in flies, I have to use a screen refresh rate of 160 Hz.  In  addition,
I am trying to display each m-sequence frame at 64 Hz (.016 ms per
frame).  Basically, as the program runs, it gets slower and  slower, as
if the buffer is getting overloaded.  Is there some more efficient  way
of doing this and maintaining speed? (I included the program below).
I would greatly appreciate any help on this.

Thank you very much, Angelique Paulk




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[visionegg] Re: Fwd: M-sequences and timing

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