.gif loop problem


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Dave
Dave
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Eric del Rio - Friday, March 17, 2017
I have been having a similar issue with using .gif in <video> as stimuli in my test (Inquisit 5). On windows machines, the program will crash after one or two instances of a .gif.

On an iMac, the program will run, but .gif files get pretty choppy from time to time (start jumping and shaking on the screen). I've tried reducing the resolution of the images going into the .gif files but it doesn't seem to make a difference. When I use static images as stimuli, the program runs fine.


As far as I can determine the problem ultimately comes from two sources:
(1) The way Inquisit handles GIFs -- it essentially expands them into stimulusframes.
(2) The fact that in your case GIFs are drawn on top of each other, i.e. introducing two sets of potentially conflicting stimulusframes in a given instance of a <trial>.

Due to platform differences, this leads to a crash under Windows and "choppiness" under OSX.

The best "quick fix" I can see is to either (a) switch to a different (non-GIF) video format or (b) split things into separate <trial>s, i.e. instead of inserting the GIFs at values.stiminterval

<trial TargBP>
/ stimulusframes = [1 = NonBP, NonFace]
/ontrialbegin = [
values.rt = 0;

   
values.stiminterval = list.stimulusinterval.nextvalue;
trial.TargBP.insertstimulustime(video.NonFace, values.stiminterval);
trial.TargBP.insertstimulustime(video.TargetBP, values.stiminterval);


]
...
</trial>

have the trial only display NonBP and NonFace and set it to /timeout = values.stiminterval; if no response occurs prior to timeout, /branch to a 2nd <trial> that displays NonFace and TargetBP.

Hope this helps.

Eric del Rio
Eric del Rio
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Dave - Friday, March 17, 2017
Eric del Rio - Friday, March 17, 2017
I have been having a similar issue with using .gif in <video> as stimuli in my test (Inquisit 5). On windows machines, the program will crash after one or two instances of a .gif.

On an iMac, the program will run, but .gif files get pretty choppy from time to time (start jumping and shaking on the screen). I've tried reducing the resolution of the images going into the .gif files but it doesn't seem to make a difference. When I use static images as stimuli, the program runs fine.


As far as I can determine the problem ultimately comes from two sources:
(1) The way Inquisit handles GIFs -- it essentially expands them into stimulusframes.
(2) The fact that in your case GIFs are drawn on top of each other, i.e. introducing two sets of potentially conflicting stimulusframes in a given instance of a <trial>.

Due to platform differences, this leads to a crash under Windows and "choppiness" under OSX.

The best "quick fix" I can see is to either (a) switch to a different (non-GIF) video format or (b) split things into separate <trial>s, i.e. instead of inserting the GIFs at values.stiminterval

<trial TargBP>
/ stimulusframes = [1 = NonBP, NonFace]
/ontrialbegin = [
values.rt = 0;

   
values.stiminterval = list.stimulusinterval.nextvalue;
trial.TargBP.insertstimulustime(video.NonFace, values.stiminterval);
trial.TargBP.insertstimulustime(video.TargetBP, values.stiminterval);


]
...
</trial>

have the trial only display NonBP and NonFace and set it to /timeout = values.stiminterval; if no response occurs prior to timeout, /branch to a 2nd <trial> that displays NonFace and TargetBP.

Hope this helps.

Thanks Dave, 

I shortened up the .gif files and optimized them so they are not such big file sizes. With the new .gif they won't overlap unless I loop them, I've tried to make the changes in the .gifs happen at a rate so that the delay during the change between non-target and target .gif files isn't so obvious.

Thanks again for all of your help

Eric
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