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vertically swapped block of pixels in video stream

Florian Bayer
Prodigy 65 points
Other Parts Discussed in Thread: DLPC350

Hello,

I am using two Lightcrafter 4500 for a scientific application, both in pattern sequence mode with input from video stream (1140x912, 60Hz). I noticed that the last ca 20 pixel of the image (i.e., the last 20px of the bottom line in the lower right corner) are swapped with the last 20px of the first line. Moreover, all pixels in a 20px-column at the right image border are shifted vertically by one line, i.e. the last 20px of the 1st line are located in the last 20px of the 2nd line, the last 20px of the 2nd line are located in the last 20px of the 3rd line, and so on.

The artIfact has no perceivable temporal frequency (i.e. no flicker). It appears static as long as the image does not change. It is invisible on uniform backgrounds and thus it can be difficult to see it in a desktop scene. It is eye catching if a fine point grid is displayed, if there is high contrast between the last line and the first lines of the streamed image, or if a horizontal edge is presented at the right image border.

I tried several bit pattern combination and timings, but it seems not to be related, and moreover, it also appears in normal video mode. I tried to manipulate frame rate and some synchronization setting via the Nvidia control panel (Windows 7, Nvidia Quadro 2000M), however with no effect on the described artifact.

Exactly the same artifact can be observed with both Lcr.

Any idea what it could be?

 

Best regards

Florian

  • 0
    TI__Expert 4720 points

    Hello Florian,

    I have not noticed this artifact before and it will require some research to determine the cause of it. Could you provide me more information about your setup so I can try to replicate it? The LightCrafter 4500 settings and your video card's timing parameters should be sufficient.

    Best regards,

    Blair

  • 0 in reply to Blair Conner
    Intellectual 340 points

    Hello Blair,

    we are seeing the same problem.

    I have tried with different graphics cards, and see the exact same symptoms as Florian. See below for a photo of the manifestation. I can add, that this problem occurs only when using the native 1140x912 in pattern sequence mode.

    Is this a general bug, or a matter of synchronisation settings?

    These are my settings:

    I know about the synchronisation requirements table in the DLPC manual, but have difficulties translating these into the correct values in the graphics cards settings. I should add that I did try various different timing settings with no visible difference.

    Regards,

    Jakob Wilm

  • 0 in reply to Jakob Wilm
    TI__Prodigy 100 points

    Jakob Wilm said:

    I know about the synchronisation requirements table in the DLPC manual, but have difficulties translating these into the correct values in the graphics cards settings. I should add that I did try various different timing settings with no visible difference.

    Regards,

    Jakob Wilm


    Hey Jakob,

         Could you please elaborate on the difficulties you are experiencing?

    Brandon

  • 0 in reply to Brandon Pollack
    Intellectual 340 points

    Hi Brandon,

    as far as I am aware, the only documentation of permissible timing settings for the LC4500 HDMI input would be the following table from the DLPC350 data sheet, DLPS029B, page 32.

    Now, we do believe that the graphics card settings shown above are in accordance with these timing requirements. As mentioned, we have tried several alternative settings; none of which resolved or altered the pixel misalignment issue in pattern sequence mode (external RGB) described and documented above. Also different computers with different graphics cards did not make a difference.

    Could you please inform us, whether this is an issue with the LC4500 hardware/firmware or the video input signal?

    In the former case -- can you give an indication of when this will be fixed?

    In the latter case -- can you please suggest appropriate timing values for all necessary fields in the graphics card settings panel?

    Thank you very much.

    Best regards,

    Jakob Wilm

  • 0 in reply to Jakob Wilm
    TI__Mastermind 30875 points

    Hello Jakob,

    I will answer on behalf of my colleague Brandon,

    We are aware of the issue; we heard similar thing from several other customers. Currently  we are investigating the issue, from our preliminary investigation it appears to be issue in the firmware. As of know we are targeting a updated DLPC350 firmware in late June or early July. Once we firm up the plan we will again reply to this thread with correct date.

    Immediate solution would be to run at lower fps 100Hz.

    Regards,

    Sanjeev