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DM368 Memory bandwidth

Bhupesh Vyas
Prodigy 30 points


Hello! I have been trying to get 32bit argb to work with 1080i video.

I've set osd0win to 24bpp and osd1win atttribute to alpha. I'm noticing artifacts when playing 1080i video and display full screen graphics on top in 24bit. The graphics image is of 1080 size. We had noticed memory bandwidth issues with DM365. Does it still exist with DM368 or did I miss some configuration?

  • 0
    TI__Mastermind 19985 points

    Bhupesh,

    What is the overall memory load in your system? I mean what all are you currently running in the system. From DM365 to DM368, memory clock has increased 70MHz which translated to theoretical 280MBps improvement. In general, you can get 60% of this bandwidth for the actual data transfers which means around 160MBps. Now, it depends that your application can still be accomodated with this extra memory bandwidth or needs more than that. So only if i understand the total DDR load in your current system, we can see what might be going wrong.

    BTW, are you doing a 1080P or 1080i60 H.264 decode also on the system?

    Regards,

    Anshuman

    PS: Please mark this post as verified, if you think it has answered your question. Thanks.

  • 0 in reply to Anshuman Saxena
    Prodigy 30 points

    Anshuman,

    Thanks for the details.

    We are using video plane at 1080i 30. The video is passthrough so there is no h.264 decode happening in this scenario.

    OSD0 plane is set for 24bit RGB. OSD1 is set for 8bit Alpha.

    Can you please gice details on how you calculate memory bandwidth in this scenario for DM368 for Graphics/Video?

    Is it standard PixelClock * PixelSize * H-ActiveSize /H-Total size? Approximated to H-Size * V-Size * PixelSize * FrameRate?

    Can you point me to any document that has more details?

    BTW, I was reading SPRUG92; in section 4.5 there description of OSD constraints for DM355 where user would see noise in full screen mode. Does DM368 has any such constraints?

    Thanks,

    Bhupesh

     

  • 0 in reply to Bhupesh Vyas
    TI__Mastermind 19985 points

    Hi Bhupesh,

    I dont see a problem from DDR memory bandwidth point-of-view in your usecase. You are capturing video, displaying video and overlaying 24bit OSD at 1080i30. Your calculation of bandwidth is actually fine to use.

    Are you seeing some problems with the above usecase from DDR perspective? What exactly is the issue that you are seeing?

    DM368 does not have the constraints that are mentioned for DM355, but it depends upon usecases and in some usecases which are memory intensive, can cause similar behavior as well.

    Regards,

    Anshuman

  • 0 in reply to Anshuman Saxena
    Prodigy 30 points

    Anshuman,

    We see artifacts on screen when video and Graphics planes are "ON" in the above mentioned configuration. The artifacts are very infrequent and random. When we ran the same software on DM365 the problem was aparant and very consistent. Hence we thought it is a memory bandwidth issue.

    Is there any register settings that I can read to check current memory bandwidth in use for display? For 32bit argb we have to set osd0 to 24bit and osd1 to 8bit for alpha attribute. right? I am wondering if I missed any other register setting.

    Thanks,

    Bhupesh