Problem running the QCamera



  • Hello,

    I'm trying to set up a simple VideoGrabber. But the VideoGrabber does not work.
    The VideoGrabber will be found, so if I print the device description it gives me the information.

    The code which does this is actually very small:

    QCamera * camera = new QCamera();
    
    QCameraViewfinder * viewfinder = new QCameraViewfinder();
    viewfinder->show();
    camera->setViewfinder(viewfinder);
    
    camera->start();
    

    It returns with the following error message:
    failed to renderstream -2147024809
    failed to openStream()
    Stream did not open

    As VideoGrabber (the one which makes problems) I have one from Digitus.
    On the other hand I have a working VideoGrabber, which is from EasyCAP. But this VideoGrabber I can just use for testing. I need the one from Digitus running, so I don't have the possiblity to change the VideoGrabber.

    Any suggestions what I can do?

    I also looked up, how I could change which input device it is using, but I didn't found sth. to this. So I think it uses the S-Video input instead of the CVBS signal. Any suggestions how I could change this?

    I'm running the Qt Version 5.1 on a Windows 7.


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Might be a silly question but did you check whether your Digitus grabber works properly outside of Qt ? Is it supported by Windows WMF ? DirectX ?



  • Thx for your quick response.

    Yes it is working outside of Qt. For example it runs in the vlc Player. But there is also the problem that I have to set the device to CVBS and do not use the default S-Video input. I'm not sure how I could change this by Qt?


  • Lifetime Qt Champion

    What devices does QCameraInfo::availableCameras() return ?



  • So I don't have QCameraInfo cause I use Qt 5.1.
    But QCamera::availableDevices() gives me the same information, I think.

    It returns the following:
    @device:pnp:\?\usb#vid_eb1a&pid_2821&mi_00#6&18118bcd&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}{54353d15-e717-4d94-b574-685ce1a209e9}

    As the device description it returns:
    USB 2821 Device


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