Video frames mixed

[cobayatron]

Hi all,

A test I'm working requires three HD cameras continuously recording different points. I manage to make a small program that records and visualizes the images but something quite strange happens. When I play the saved files, I can see how in each file (recorded by a particular camera) appears frames coming from any of the others two.(???) I am not sure about the reason since the paths seems properly set.

Thanks!

[GeorgeAF]

Hi cobayatron,

My name is George and I’m an Applications Engineer at National Instruments. I see that you are using NI Vision Acquisition Software to record images from 3 cameras in different positions and visualise the data as 3 separate IMAQ images. However some of the images you are recording are being mixed in with the other cameras data.

To help troubleshoot the problem could you give me some more details on how your test is set up and the hardware you are using. This will help me get a better understanding of the whole system which will make it easier to move towards a possible solution to your problem. Also if you do not have the newest version of the driver for Vision can you try updating it and see if this helps the issue. There is a link to the newest version below.

http://www.ni.com/download/ni-vision-acquisition-software-february-2015/5149/en/

Whilst I wait for a reply I will continue to do my own research into the problem and let you know if I find any more relevant information or troubleshooting steps.

Regards,

George

[GeorgeAF · Accepted solution]

Hi cobayatron,

I’ve been having a deeper look at the code you attached to your post. The general architecture for recording separate AVI files is great but I have a couple of suggestions that may help to resolve your problem.

I can see that when you first create a memory location for images you name all 3 “Initial”. Try changing the strings from “Initial” to separate names, for example “Initial 1”, as this may be causing the memory allocation to become mixed up. Also you are creating 3 new AVI files with each iteration of the while loop but they are never closed. I suggest adding an IMAQ AVI2 Close subVI for each camera after the for loop but within the while loop and connect the AVI refnum and error output terminals of the Write Frame subVIs to the equivalent input terminals of the close subVIs. This will close each AVI file once all the data has been added before the next set of files are created.

Try these steps as well as the steps I mentioned before and if the problem is not resolved let me know if there have been any changes in the result and we can try some other steps to resolve the problem.

Regards,

George

[cobayatron]

Hi George,

Thanks for your help. 

You're right, the issue of the mixed images has been solved by changing the deafault name to a exclusive name for each camera, thanks!

I'll also add  IMAQ AVI2 Close subVIs as you suggest to improve my architecture.

Thanks indeed!!!