Save Video on XPC Target

I am getting a video stream from my xpc target machine via USB webcam, but I would like to be able to save the video file to the internal Hard Drive of my target machine. Does anyone know how to go about doing this?

Answer 1

[Kaustubha Govind]

Not a 100% sure that this is the right solution, but how about connecting the output of the webcam driver to a xPC File Scope block?

[Nicholas]

I've tried to use the XPC file scope block, but it appears that it can't take two-dimensional signals. Even after saving R,G,B channels independently, I still get an invalid dimension error.

[Kaustubha Govind]

Are the signals still 2-D even after splitting into R, G and B channels? Try turning on Format>Port/Signal Displays>Signal Dimensions and see if anything seems off?

[Nicholas]

Yes. The signals are 2-D after splitting into R,G,B channels and the xpc file scope block seems to not accept a 2 dimensional signal.

[Kaustubha Govind]

Perhaps you could split those further into 1-D signals? Not sure if there is a way to log 2-D or n-D signals to disk with xPC Target. Please consider putting in an enhancement request with MathWorks Technical Support for this.

[Nicholas]

I was considering that, but the input image is a [480 640] image matrix. I split that into 1D signals, I would either have 480 row vectors or 640 column vectors, which I'm almost certain xpc target cannot support.

[Walter Roberson]

I thought there was a reshape block?

[Nicholas]

Thanks Walter, I'll try this out on Monday when I have access to the Target machine

[Walter Roberson]

http://www.mathworks.com/help/toolbox/simulink/slref/reshape.html

[Nicholas]

Walter, I tried your suggestion on the R channel of an RGB image, and it seemed to reshape the 640*480 matrix to a single column vector (which is necessary to save on xpc target). The problem was that when I tried to retrieve the data, it appears that xpc target only recorded one value (perhaps the first element in the column matrix) per sample time. Therefore, I only was able to retrieve one value for every sample time.

I'm somewhat lost as to any other way I could save video to xpc target. As I've already mentioned, wireless transmission then saving on another computer is not an option since the target machine is used on a mobile robot that moves out of range of the wireless network.

[Kaustubha Govind]

Nicholas: Sorry, I'm out of ideas. Could you try contacting MathWorks Tech Support to see if they have a better solution?

[Nicholas]

Thanks for your help. I've contacted technical support for assistance.

[Aram Simonian]

Hi, I have exactly the same problem. The only difference is that I use a CameraLink camera. What did the MathWorks support suggest to you? Thanks for any advice.

Answer 2

[Pika]

Can you give me some explanation about how to read usb camera? I have set up a target, which works well without reading usb camera. After add the usb video device module to the model, the following problems exist: (1) This usb video device module can not detect the camera connected to the target. If I connect this camera to the development computer, it works well with the vision machine toolbox. (2) This application can be loaded to the target, but I cannot start it and a error message "Video device is not found" is displayed.