Presenting slide-object while video is playing

[francesco biondi]

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]

I ve just realised I made a mistake..

when I write slide-objects

I mean text-objects

Sorry

waiting for reply!

[David McFarlane]

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 .

-----
David McFarlane
E-Prime training
online: http://psychology.msu.edu/Workshops_Courses/eprime.aspx
Twitter: @EPrimeMaster (twitter.com/EPrimeMaster)

[francesc...@ymail.com]

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 <mcfa...@msu.edu>

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Francesco Biondi

[David McFarlane]

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, francesc...@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:mcfa...@msu.edu>mcfa...@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

>.
>
>-----
>David McFarlane
>E-Prime training
>online:

><http://psychology.msu.edu/Workshops_Courses/eprime.aspx>http://psychology.msu.edu/Workshops_Courses/eprime.aspx
>Twitter: @EPrimeMaster
>(<http://twitter.com/EPrimeMaster>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

[David McFarlane]

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

[francesc...@ymail.com]

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 <mcfa...@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, francesc...@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:mcfa...@msu.edu>mcfarl...@msu.edu>

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--
Francesco Biondi

[CarF]

Hi Francesco,

I have a similar problem on https://groups.google.com/g/e-prime/c/AJxClVPf_fY.

Did you manage to solve it?

If so, can you give me some advices?

Thank you!!