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[AM3894 HDVPSS] Blending more than 3 graphic layer between frames

Heng Wei Chang
Prodigy 20 points
Other Parts Discussed in Thread: AM3894

Hi,

I have project use AM3894 to display gui in an AOI system. Refer to the HDVPSS user guide (SPRUHH4), the graphics from 3 GPRX can be blended in COMP and output to VENC and / or feedback to DDR memory.

I wonder that is it possible to blend more than three graphic layers by using two GPRX and the VIP subsystem memory feedback path? Here is the idea: two GPRX move two source layers data into the DVO2 blender, feedback the output to one of the source layer and change the other one to a new layer.

I have tried to write three list (two for GRPX inbound descriptor and one for VIP outbound descriptor) to implement the idea, and more than 3 layers can be blended together as expected. But the blender seems work at the frame rate of corresponding VENC, which makes delay between each layers. To overcome this effect, I tried changing the synchronize source of descriptors from DVO2 to LM FID and got the same result.

My problem is how to make the blender faster and not constrained to the frame rate of VENC? What descriptor parameters should I set up? (I control HDVPSS in register level, not in linux).

Best regards,

Heng Wei

  • 0
    TI__Guru**** 420475 points

    You will need to stop the venc and disable the pclk connected to it.

     

    Rgds,

    Brijesh

  • 0 in reply to Brijesh Jadav
    Prodigy 20 points

    Hi Brijesh,


    Thanks for your answer, it works!

    Now, I have another question about what is the maximum bandwidth of this loop? I want to estimate how many layers can be overlaid between frames under 1080p@60Hz.

    In addition to blend graphic layers using GRPX0, GRPX1 and DVO2, the blended layer is shown on HDMI and HDCOMP simultaneously from GRPX2. When HDMI and HDCOMP are both switched on, there is a horizontal shift on HDMI. The problem disappeared when only single blender is switched on or the resolution goes down below 720p.

    Any solution to this problem?


    Best regards,

           Heng Wei