Presenting slide-object while video is playing

Fri May 18 10:22:44 UTC 2012

thanks david for your suggestions.

so far the only available idea is editing my video inserting some objects
overlaying it;
then play the edited video in eprime and gather participants response to
the objects onset
via Wait-objects.
The problems related to this method concern timing, since I will have some
variable (video's frame rate
and monitor's refresh rate) I cannot control.

I dont have any other better ideas.
>From matlab, any suggestions too.

2012/5/15 David McFarlane <mcfarla9 at msu.edu>

> Francesco,
>
> Since you asked for suggestions, I took a little trip down memory lane, to
> the days before we limited our methodology to what could be done with
> digital computers.  Back in the early 1980s I did visual psychophysics, and
> back then if we needed to superimpose stimuli we would just use a
> half-silvered mirror set at 45° in front of the subject.  So here's how you
> could do this the old-school way:  Present your movie on one display
> screen, and your overlay on a second display screen (EP2 can do this now).
>  Put a half-silvered mirror in front of the subject, angled 45° relative to
> the subject.  Put one display (e.g., the movie) straight beyond the mirror,
> and the second display off at 90° to the mirror.
> Voilà!  Now the subject looks through the mirror and sees the two displays
> combined.
>
> You might also achieve much the same effect with a pair of video
> projectors aimed at the same screen.  Of course, these methods make both
> displays translucent, so if you want, say, the red square to completely
> occlude the underlying video then this will not work.  I cannot think of
> any way around that, perhaps someone else can do better.
>
> -- David McFarlane
>
>
>
> At 5/15/2012 10:24 AM Tuesday, David McFarlane wrote:
>
>> Francesco,
>>
>> Both MATLAB and Presentation have better visual stimulus capabilities
>> than E-Prime (though I don't know anything about how they do video).  Even
>> so, I would not be surprised if they failed to do what you ask here.  Due
>> to the very nature of video presentations, what you ask requires real-time
>> on-the-fly video mixing capabilities, which is a very tall order.  I know
>> that intuitively, overlapping a couple of visual stimuli seems trivial, but
>> if you think through the mechanics of how moving images are made by
>> rewriting the screen with each frame, you will see that overlapping stimuli
>> with video is not at all trivial.
>>
>> Good luck,
>> -- David McFarlane
>>
>>
>> At 5/15/2012 04:33 AM Tuesday, francesco.biondi at ymail.com wrote:
>>
>>> Hi David,
>>>
>>> the target (eg, a red square) I need to show to participants overlays
>>> the video,
>>> then I cannot use a Slide Objects composed by multiple objects
>>> (video+text).
>>>
>>> I ve seen you mentioned Matlab; I thought to consider it, but I have no
>>> updates from that side.
>>>
>>> Indeed, about video-editing I am trying to run this way, but I think I
>>> would have problems
>>> with timing, because I should consider both the video's frame-rate and
>>> the monitor refresh-rate;
>>> I guess this may be problematic for the reliability of recorded times.
>>>
>>> Suggestions?
>>>
>>> 2012/5/14 David McFarlane <<mailto:mcfarla9 at msu.edu>mcfa**rla9 at msu.edu<mcfarla9 at msu.edu>
>>> >
>>> Does any part of your superimposed text overlap with the video?  If so,
>>> then you will run into the problem discussed at <
>>> http://groups.google.com/**group/e-prime/browse_thread/**
>>> thread/2bcf7ebef4211832<http://groups.google.com/group/e-prime/browse_thread/thread/2bcf7ebef4211832>
>>> >http:/**/groups.google.com/group/e-**prime/browse_thread/thread/**
>>> 2bcf7ebef4211832<http://groups.google.com/group/e-prime/browse_thread/thread/2bcf7ebef4211832>.
>>>
>>> -----
>>> David McFarlane
>>> E-Prime training online: <http://psychology.msu.edu/**
>>> Workshops_Courses/eprime.aspx<http://psychology.msu.edu/Workshops_Courses/eprime.aspx>
>>> >**http://psychology.msu.edu/**Workshops_Courses/eprime.aspx<http://psychology.msu.edu/Workshops_Courses/eprime.aspx>
>>> Twitter:  @EPrimeMaster (<http://twitter.com/**EPrimeMaster<http://twitter.com/EPrimeMaster>
>>> >twitter.com/**EPrimeMaster <http://twitter.com/EPrimeMaster>)
>>>
>>>
>>>
>>> At 5/14/2012 08:14 AM Monday, francesco biondi wrote:
>>> I ve just realised I made a mistake..
>>>
>>> when I write slide-objects
>>> I mean text-objects
>>>
>>> Sorry
>>>
>>> waiting for reply!
>>>
>>> Il giorno lunedì 14 maggio 2012 11:53:50 UTC+2, francesco biondi ha
>>> scritto:
>>> Hi all!
>>> I ve posted a topic on PSTforum but..no reply yet..
>>> then, I will turn my problem over to you..
>>>
>>>
>>> I need to show a video to participants using a MovieDisplay-object.
>>> While the video is playing, I need to show, superimposed to the video,
>>> some slide-objects covering not the whole display, but only a small
>>> part of it. After participant's response to the object, the object
>>> will disappear, but the video will continue without any interruption.
>>>
>>> I dont know how I can show slide-objects together with the video
>>> without interrupting it (letting it play without crashes).
>>>
>>> Bye!
>>>
>>> and thanks in advance
>>>
>>> --
>>> Francesco Biondi
>>>
>>
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>

-- 
*Francesco Biondi*

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