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FBDEV vs. V4L2 on DM8168

_Ralph_
Guru 10685 points
Other Parts Discussed in Thread: TVP7002

I'm trying to work out which of the .xem3 files I should be loading for the HDVPSS on the DM8168 using the new EZSDK, 5.03.01.15.

One of the 2 files has the suffix "v4l2", the question is which should I be using?

The VPSS user guide seems to imply that FBDEV is used for GUI applications and V4L2 is used for "display streaming" but what if I need to be able to capture and display video using a GUI?


Thanks,

Ralph

P.S.

I don't have a tvp7002 chip in my final design.

  • 0
    TI__Prodigy 495 points

    Hi Ralph,

    V4L2 display can be used with both firmware.For V4L2 capture requires an alternate HDVPSS firmware to be loaded at boot time.That is the reason two firmware are provided.

    V4L2 firmware for V4L2 capture :-

     $ cp /usr/share/ti/ti-media-controller-utils/load-hd-v4l2-firmware.sh /etc/init.d/load-hd-firmware.sh

    $ sync

     Now power cycle your board.

     To revert your changes back to use the default firmware which supports OMX Capture please run the following command

     $ cp /usr/share/ti/ti-media-controller-utils/load-hd-firmware.sh /etc/init.d/load-hd-firmware.sh

    $ sync

     Now power cycle your board.

    Thanks and regards

    Sachin Kumar

  • 0 in reply to Sachin Thathgur
    Guru 10685 points

    Hi Sachin,

    Thanks for the reply. This begs the question, what reasons are there for using V4L2 capture? I read somewhere that if you use V4L2 you cannot use the OpenMAX encoding framework - is this correct?

    Ralph

  • 0 in reply to _Ralph_
    Genius 4615 points

    Hi Ralph,

    There are many ways of doing things.  We're currently using FBdev for image display with openCV without a GUI.  You create a 3 channel image in openCV and then simply copy the pixels to the frame buffer.  We haven't tried to use V4L2, though we may use it later for image capture.  I don't want all of the extra over-head associated with OMX.  For capure, at the present, we're using DC1394 with a USB camera.

    Lee

     

  • 0 in reply to Lee Holeva
    Guru 10685 points

    Hi Lee,

    Thanks for the info. I think that initially we won't need any video encode/decode capability and are just sticking with a GUI, however further down the line we'll definitely need the H264 codecs. Ideally we'd use the right framework from the outset.

    If the V4L2 framework is going to help us capture data externally in a particular format then we should get familiar with it ASAP. Ultimately, low latency is going to be important to us.

    Ralph