MATLAB can't work with webcam

I'm trying to connect webcam in my project, but MATLAB throws an error.

Webcamlist don't find any cam:

>> webcamlist

ans = 

{}

Device id:

>> imaqhwinfo('linuxvideo')

ans = 

         AdaptorDllName: '/home/voland/Documents/MATLAB/SupportPackages/R2014b/osgenericvideointerfac...'
      AdaptorDllVersion: '4.8 (R2014b)'
            AdaptorName: 'linuxvideo'
              DeviceIDs: {[1]  [2]}
             DeviceInfo: [1x2 struct]

Camera is available, but don't start:

>> vid = videoinput('linuxvideo',1,'YUYV_640x480')

Summary of Video Input Object Using 'UVC Camera (046d:0825)'.

     Acquisition Source(s):  Camera 1 is available.

    Acquisition Parameters:  'Camera 1' is the current selected source.
                             10 frames per trigger using the selected source.
                             'YUYV_640x480' video data to be logged upon START.
                             Grabbing first of every 1 frame(s).
                             Log data to 'memory' on trigger.

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

                    Status:  Waiting for START.
                             0 frames acquired since starting.
                             0 frames available for GETDATA.

>> preview(vid)
Warning: Unable to reset the crop area.  Perhaps the device is in use. 
Error using imaqdevice/preview (line 176)
Could not connect to the image acquisition device.  Device may be in use.

dmesg:

[11484.585199] usb 4-1.1: new high-speed USB device number 7 using 
ehci-pci
[11484.888728] uvcvideo: Found UVC 1.00 device <unnamed> (046d:0825)
[11484.979398] input: UVC Camera (046d:0825) as  
/devices/pci0000:00/0000:00:1d.0/usb4/4-1/4-1.1/4-1.1:1.0/input/input23

This trick can't help for me:

LD_PRELOAD=/usr/lib/libv4l/v4l2convert.so sudo ./matlab
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so sudo ./matlab

Cameras great work on Windows 7x64 with MATLAB 2015b and on Cheese (Linux). My system: Arch Linux x64 with MATLAB 2014b. I have no idea about the resolve this problem. I'm hope for your help. Thanks!

[Walter Roberson]

Could you confirm that you installed the Webcam support package?

[Marat Gareev]

How can I do this? So, my cameras correctly work in Cheese, V4L2ucp

[Image Analyst]

It would tell you if you didn't have it installed. Since it didn't tell you, you do have it installed.

Perhaps you might also need the OS Generic Video Interface hard ware support package from the "Add ons" button on the Home tool strip tab.

[Marat Gareev]

I installed this package

[Image Analyst]

Does linux have anything like Windows Device Manager, where you can see what devices are attached to your computer? If so, does it show the webcam?

[Marat Gareev]

Yes of course. I can see the connected devices from dmesg:

[11484.585199] usb 4-1.1: new high-speed USB device number 7 using 
ehci-pci
[11484.888728] uvcvideo: Found UVC 1.00 device <unnamed> (046d:0825)
[11484.979398] input: UVC Camera (046d:0825) as  
/devices/pci0000:00/0000:00:1d.0/usb4/4-1/4-1.1/4-1.1:1.0/input/input23

I can also see what programs are using the camera:

➜  ~ sudo lsof | grep video0
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs
      Output information may be incomplete.
...
MATLAB    13813 14145    root  496u      CHR               81,0       0t0      13722 /dev/video0
MATLAB    13813 14146    root  496u      CHR               81,0       0t0      13722 /dev/video0
MATLAB    13813 15173    root  496u      CHR               81,0       0t0      13722 /dev/video0
MATLAB    13813 15180    root  496u      CHR               81,0       0t0      13722 /dev/video0
v4l2ucp   15764          root    8u      CHR               81,0       0t0      13722 /dev/video0
QProcessM 15764 15765    root    8u      CHR               81,0       0t0      13722 /dev/video0
mplayer   15766          root  mem       CHR               81,0                13722 /dev/video0
mplayer   15766          root    5u      CHR               81,0       0t0      13722 /dev/video0
mplayer   15766          root    8u      CHR               81,0       0t0      13722 /dev/video0
mplayer   15766 15767    root  mem       CHR               81,0                13722 /dev/video0
mplayer   15766 15767    root    5u      CHR               81,0       0t0      13722 /dev/video0
mplayer   15766 15767    root    8u      CHR               81,0       0t0      13722 /dev/video0

But when I connect to Matlab, no programs are using the camera (It is shown v4l2ucp for example)

Answer 1

[Renan Augusto Starke]

Hi,

in order to make cameras to work with Matlab in Arch Linux you should install almost all gstreamer plugins:

Take a look: https://www.archlinux.org/packages/?sort=&q=gstreamer&maintainer=&flagged=