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Selecting Input Channel for QCamera

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  • K Offline
    K Offline
    kkrizka
    wrote on 27 Sept 2017, 22:28 last edited by
    #1

    Hi all,

    I am using a Hauppauge ImpactVCB model 558 video capture card to capture the output of several analogue cameras on Linux. This card has 4 input channels (3 RCA, 1 s-video). On Linux, the card shows up as a single /dev/videoX device and can be access using V4L2. The required channel can be selected using the "input" setting. I've tested it using mplayer and I see the expected image on two of the channels. So I know the card works. I've used the following command for this test:

    mplayer tv:// -tv driver=v4l2:norm=NTSC:device=/dev/video0:input=0

    Next I would like to capture the video using the QCamera class, so I can analyse the image using Qt. Qt detects the camera at /dev/video0 and correctly shows the image on the input channel 0. However I do not see an option in the class to select a different input channel. Is it possible to change such settings (input channel, NTSC vs PAL) of a camera using the QCamera class?

    --
    Karol Krizka

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    • S Offline
      S Offline
      SGaist
      Lifetime Qt Champion
      wrote on 28 Sept 2017, 21:38 last edited by
      #2

      Hi,

      I might be wrong but I have a doubt about that.

      Out of curiosity, do you have the equivalent line for GStreame ?

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

      K 1 Reply Last reply 2 Oct 2017, 22:40
      0
      • S SGaist
        28 Sept 2017, 21:38

        Hi,

        I might be wrong but I have a doubt about that.

        Out of curiosity, do you have the equivalent line for GStreame ?

        K Offline
        K Offline
        kkrizka
        wrote on 2 Oct 2017, 22:40 last edited by
        #3

        @SGaist, I do not have an equivalent line for gstreamer. I looked at the output of gst-inspect v4l2src, but don't see the input property there. I can change the norm there though.

        I've ended up implementing the reading from the capture card using the V4L2 functions and converting the output to an QImage.

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        27 Sept 2017, 22:28

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