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RGB video capture and YUV encoding of DM814x?

Jun_Zhang
Expert 2425 points

Greetings,

In this thread, there is a discussion regarding video capture and encoding capability of Davinci.

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/156922.aspx#571293

So, basically DM814x is able to capture RGB888 and only able to encode under YUV420, right?

Now, I am able to capture RGB888 discrete sync, how can I down_sampling the data to be encoded by Soc?

My capture is based on v4l2 API instead of v4l2src from gstreamer and from here I want to use omx_h264enc and other gstreamer elements to do video processing.

Could anyone point out me a direction to go?

Regards,

Jun

  • 0
    Expert 2425 points

    What I want is capturing RGB video data, convert it into yuv420, load it on the omx_h264enc.

    Ok, after going through my problem again, I guess I figure out it. Please correct me if I am wrong.

    Although the HDMI decoder output is RGB , in the  ti81xx_fb, I need set the video format as yuv instead of RGB?

    Regards,

    Jun

  • 0 in reply to Jun_Zhang
    TI__Mastermind 20245 points

    Hi.

    HDVPSS can convert incoming RGB data to YUV data. You need to set RGB only in ti81xx_fb. But while doing set_format you need to select the dataformat as NV_12. So internally driver will convert from RGB-->YUV444-->YUV422-->YUV420. Out in memory will be YUV420.

    Regards,

    Hardik Shah

  • 0 in reply to HardikShah
    Expert 2425 points

    Hi Hardik,

    Thansk for your reply very much.

    I assume that "set_format" you mentioned should be inside SaLoopBackFbdev.c

    So, I have changedcapt.fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_NV12, and I am going to run some test.

    Although, I tried V4L2_PIX_FMT_YUV422P and when I replayed the captured data it is still RGB.

    static int setupCapture(void)
    {

    //...

      capt.fmt.fmt.pix.bytesperline = capt.fmt.fmt.pix.width ;
     capt.fmt.fmt.pix.sizeimage = capt.fmt.fmt.pix.bytesperline *
      capt.fmt.fmt.pix.height*3/2;
     capt.fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_NV12;//V4L2_PIX_FMT_YUV422P;//V4L2_PIX_FMT_RGB24;//
     ret = ioctl(capt.fd, VIDIOC_S_FMT, &capt.fmt);

    //...
     }

     

    Regards.

     

    Jun

  • 0 in reply to HardikShah
    Expert 2425 points

    Hi Hardik,

    Now I can capture and converted into yuv422p and I am using a software to replay, which shows the captured data is fine.

    However, when trying to convert the video data into yuv420 using above settings, and I cannot replay it properly.

    Do you know why is that?

    Regards,

    Jun

  • 0 in reply to Jun_Zhang
    TI__Mastermind 20245 points

    Hi,

    This may be because most of the player works with YUV420 planar format i.e. y, u and v all three components are in different planes. But output of capture is YUV420 semi planar where y is in one plane and u and v interleaved in one plane. So there are total 2 planes. Codecs also works with same format so you will be able to encode.

    Regards,

    Hardik Shah