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DM8148 V4L2 buffer and rotation

Ashwin Bihari
Intellectual 430 points

Hello,

I have a custom board based on the DM8148 where I'm streaming (currently) NTSC video to the S-Video output using the V4L2 (/dev/video3) device. This works perfectly fine, but one of the features I have to implement is inverting of the video, i..e, a rotation of 180 degrees. 

I'm more familiar with the OMAP3/VRFB subsystem which had the rotation support, but from preliminary search for DM8148 and rotation yielded conflicting answers about the use of Tiler on EZSDK. I'm based on EZSDK 5.04 right now, and a couple of posts suggest that Tiler support is integrated for scaling but not for rotation?

My path would be, S-Video -> VIN1 -> /dev/video5 -> APP -> /dev/video3. So inbetween VIN1 and /dev/video5, I want to flip a switch or something to have the image be inverted/rotated so that I can continue passing it along for display.

Could I get a definitive answer on whether rotation is supported on the DM8148 with EZSDK 5.04 for both FBDEV and V4L2 output devices and if so how to enable and configure it. If Tiler support is not available, what are the alternates available to me to invert the video?

~Ashwin

  • 0
    TI__Mastermind 20245 points

    Hi,

    Ashwin Bihari said:
    I'm more familiar with the OMAP3/VRFB subsystem which had the rotation support, but from preliminary search for DM8148 and rotation yielded conflicting answers about the use of Tiler on EZSDK. I'm based on EZSDK 5.04 right now, and a couple of posts suggest that Tiler support is integrated for scaling but not for rotation?

    This is a hardware feature but rotation is not supported in software.

    Ashwin Bihari said:
    My path would be, S-Video -> VIN1 -> /dev/video5 -> APP -> /dev/video3. So inbetween VIN1 and /dev/video5, I want to flip a switch or something to have the image be inverted/rotated so that I can continue passing it along for display.

    As said above this is not supported in software as of now.

    Ashwin Bihari said:
    Could I get a definitive answer on whether rotation is supported on the DM8148 with EZSDK 5.04 for both FBDEV and V4L2 output devices and if so how to enable and configure it. If Tiler support is not available, what are the alternates available to me to invert the video?

    If you data is small you can use EDMA to do rotation. But hardware rotation like VRFB is not supported in software using tiler.

  • 0 in reply to HardikShah
    Intellectual 430 points

    HardikShah said:

    If you data is small you can use EDMA to do rotation. But hardware rotation like VRFB is not supported in software using tiler.

    Hi Hardik,

    For starters we will be using standard definition video at either NTSC or PAL resolution so no greater than 720x576 for the frames, but at some point we need to support high definition at 1080i as well.

    Could you please provide a link or some idea on what doing the rotation with the EDMA would entail? Looking at the DM8148 TRM, I see the EDMA used for DMA transactions for many peripherals and work. I'm not clear on how EDMA fits in here to do the rotation?

    ~ Ashwin