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DM6437 RGB output

Rob Beck
Intellectual 970 points

I would like to output to a VGA PC monitor. I have a lead that has 3 RCA plugs (coloured R, G and B!) and goes to a VGA connector to a PC monitor.

My first question is hardware related before I get into the software: Can the DM6437 video board actually do RGB? (I have already got the demo to operate with composite and S-video)

My second question is if it can then how do I adapt the demo code that comes with the DM6437 video board to do such?

I have looked at the code in app_block_video_output where in the demo the self->vpbeVencConfigParams.displayStandard is assigned to PSP_VPBE_DISPLAY_PAL_INTERLACED_COMPOSITE (for example). PSP_VPBE_DISPLAY_PAL_INTERLACED_S_VIDEO also works. I have tried PSP_VPBE_DISPLAY_PAL_INTERLACED_COMPONENT but the PC monitor does not respond.

I wondered if it was because YCbCr was being generated rather than RBG, so I changed self->viddecParams.forceChromaFormat from XDM_YUV_422ILE to XDM_RGB in app_block_video_decode but it did not make a difference.

 

If RBG is possible then where in the documentation is it specified which DAC outputs drive each: I looked at the code, schematics, PDFs that come with the board but no clues.

  • 0
    TI__Genius 15310 points

    Hello Rob,

    You have to convert YUV component to RGB.  Please see this posted:

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/99/p/65239/235393.aspx#235393

    Regards,

    Viet

  • 0 in reply to Viet Dinh
    Intellectual 970 points

    Thanks for the information: It tells me the maths to convert YCbCr to RGB colour space.

    However, what I really need to know is if it is possible to connect the DM6437 direct to a typical LCD PC monitor with a VGA input?

    I do have my doubts because the DM6437 seems to be outputting typical PAL settings - 25 fps, 15.625 line refresh - when playing PAL material. However, a typical PC monitor does not like these frequencies and wants 60hz or upwards fps and possibly different line refresh.

    I've hacked down the demo code so I can stream material over Ethernet and play it on a TV (component YCbCr or  composite) but looking at the parameters for the app_block_video_decode and elsewhere cannot find any obvious option to say "I want VGA output"

    We can buy a composite or S-video to VGA converter but I would like to know if the DM6437 can be connected directly somehow?

  • 0 in reply to Rob Beck
    TI__Genius 14405 points

    Rob, the DM6437 VPBE DAC only supports SDTV output, that means PAL or NTSC only. If you want a refresh rate like 60Hz, you will have to use the VENC (digital output), and use an external DAC to produce VGA signal.

    If you have any Linux/demo related question, you can post them on our Linux forum.

    regards,

    Paul