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DM365: capture video without any video decoder

Marco Braga
Expert 1780 points

Other Parts Discussed in Thread: TVP7002

Hello,

On DM365 I need to capture BT656 with embedded syncs from an external video module that provides video in this format. It seems to me that current  drivers are "tied" to one of the supported video decoders (i.e. TVP7002, TVP514x, etc). In my case there is no decoder at all, so I'd like to use existing vpfe software support to capture BT656 without having to load any specific decoder driver. Is there any "vanilla capture" driver I can use or must I rewrite a "fake decoder" driver?

 

  • 0
    TI__Mastermind 37340 points

    Hi Marco,

    On our DM365 EVM, analog video input (composite or component) is provided to the EVM, hence we need the decoders to do analog-to-digital conversion since the DM365 expects BT.656  (digital video interface).  Therefore the video capture driver (V4L2) manages this video input path and configures both DM365-VPFE and TVPxxxx hardware.  Therefore, my question would be what is the external part providing the BT.656 input to DM365.  There is no vanilla driver which only controls VPFE, therefore you will likely need to replace TVP portion of V4L2 video capture driver to manage whatever external part is feeding the BT.656 data to DM365 (e.g. V4L2 controls video input path ).

  • 0 in reply to Juan Gonzales
    Expert 1780 points

    Juan,

    there are video modules (i.e. sensor + optics modules) produced by various manufaturers (i.e. sony, etc) that provide digital video in BT656 with embedded sync format. There is not need for external decoder.

    I've checked the vpfe driver provided in DM365 PSP and it seems to me that there is no way to capture BT656 on the video port in a more "generic" way. I think the only way is to write a stripped down "decoder" driver, without any i2c command and similar.

    I've hoped to find something already done, but it should not be too difficult to do.

    Thanks again!

     

  • 0 in reply to Marco Braga
    Intellectual 900 points

    Hi Marco,

    I am also trying to do something similar as I have external source which provide BT656 output to DM365. What changes would be required in driver to support this feature?

  • 0 in reply to vipul mahajan
    Genius 3120 points

    Hi Vipul,

    You need to write a dummy decoder driver (with any i2c/spi commands). You need to register this driver to platform driver.

    Once you have the dummy decoder driver register and you call V4l2 drivers from application it will initialize your DM365 video front end for capture.

    You can take example of kernel/drivers/media/video/tvp7002.c driver and write your own dummy driver.

    Regards,

    Krunal

  • 0 in reply to Krunal Patil
    Intellectual 900 points

    Thanks Krunal,

    I have another doubt regarding BT656 interface & V4L2. My input video is of resolution 320 x 256, CIF, QCIF etc. Do I need to modify V4L2 driver to support these resolutions? Or V4L2 can work with these resolutions? Actually my applications needs to detect the resolution detected at BT656.

  • 0 in reply to Krunal Patil
    Intellectual 340 points
    Does anyone have an example of writing a dummy driver for a direct feed BT656 signal? I have been struggling with this and would appreciate any type of help.