Cant't Change FramesPerTrigger in videoWriter

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Eirik Furuholt 2021-4-22

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https://ww2.mathworks.cn/matlabcentral/answers/809840-cant-t-change-framespertrigger-in-videowriter

评论： Eirik Furuholt 2021-4-23

Hello,

When i try to change the number of fremes per trigger in the it just resets to 10. And when i open the 1x1 videoinput in the workspace it says 10.

See pictures for a better explantion

Is it a bug in R2020b?

i have tried the following:

Open the 'vidobj' 1x1 videoinput variable in the workspace and change there.

set(vidobj, 'FramesPerTrigger', 50); %this code
vidobj.FramesPerTrigger=50 % and this code

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Answer 1

Walter Roberson 2021-4-22

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https://ww2.mathworks.cn/matlabcentral/answers/809840-cant-t-change-framespertrigger-in-videowriter#answer_681810

Frames Per Trigger is not a documented property of Videowriter or of Videoreader

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Eirik Furuholt 2021-4-22

在 MATLAB Online 中打开

Thank you for your reply.

Here is the setup part of the code and what it returns:

Summary of Video Input Object Using 'OBS-Camera'.

Acquisition Source(s): input1 is available.

Acquisition Parameters: 'input1' is the current selected source.

50 frames per trigger using the selected source.

'YUY2_1280x720' video data to be logged upon START.

Grabbing first of every 1 frame(s).

Log data to 'disk' on trigger.

Trigger Parameters: 1 'immediate' trigger(s) on START.

Status: Waiting for START.

0 frames acquired since starting.

0 frames available for GETDATA.

---------------------

What i don't understand is where the FramesPerTriger =10 comes from. As you can see above, it kinda works.

% video setup  
numFrames=50;
set(vidobj, 'FramesPerTrigger', numFrames)
vidobj.FramesPerTrigger=numFrames
vidobj=videoinput('winvideo', 2, 'YUY2_1280x720')
currentLoggingMode = vidobj.LoggingMode;
set(vidobj, 'LoggingMode');
vidobj.LoggingMode = 'disk';
logfile = VideoWriter('logfile.avi', 'Motion JPEG AVI');
vidobj.DiskLogger = logfile;
writing=false ;%bool used somewhere else

Walter Roberson 2021-4-22

The very first line of the blurry image of code that you posted is start(vidobj). Your if after that does an additional start(vidobj) even though you already started it. Then you try to change the frames per trigger. However as documented, that property is read-only while the reader is started.

Eirik Furuholt 2021-4-23

Now i understand, thanks!

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