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LCr4500:HDMI input 912x1140@56Hz

Masayuki Iwata
Intellectual 710 points
Other Parts Discussed in Thread: DLPC350

Hi,

On the LCr 4500, images were projected from the HDMI input with the settings below. For the video generator setting, the image size was 912 x 1140 and the frame rate was 74 Hz. After that, the setting of the video generator was changed, and only the frame rate was changed to 56 Hz However, like the attached movie, fluctuations like jitter occurred in the image. What is the cause?

Best regards, Masa

Settings for 74Hz input

 

Settings for 56Hz input

 

 

  • 0
    TI__Mastermind 30600 points
    Hi Masayuki-san,

    It appears that your image has different color content for each of the bit planes. If you repeat the same bit planes 3 times do you still see the same flickering effect?

    Thanks,
    Paul
  • 0 in reply to Paul Goedeke
    Intellectual 710 points

    Hi Paul,

    Thank you for answering. Yes. I tried two ways. One is when different bit planes (G - B - R) are displayed with the same color. The other is when display the same bit plane (G - G - G) with the same color. As a result, the flickering effect occurred in both cases.

    Best regards,

    Masa

      

  • 0 in reply to Masayuki Iwata
    TI__Mastermind 30600 points

    Hi Masa,

    My next question is, did you upload the image you are displaying in the correct resolution? They need to be 912x1140 otherwise you'll get artifacts like you're seeing.

    -Paul

  • 0 in reply to Paul Goedeke
    Intellectual 710 points

    Hi Paul,

    Thank you for answering. Image data is generated by PC graphic board.

    The PC settings are shown below. It seems that it is outputting with a size of 912 x 1140.

    Please check with your Lightcrafter 4500.

     

    Best Regards,

    Masa

  • 0 in reply to Masayuki Iwata
    TI__Mastermind 30600 points
    Hi Masa,

    I have tested on my Lightcrafter with your settings and am not seeing the behavior that you are reporting. The next thing you should do is check that your input video settings match the requirements given in the DLPC350 datasheet, section 6.11. www.ti.com/.../dlpc350.pdf

    -Paul
  • 0 in reply to Paul Goedeke
    Intellectual 710 points

    Hi paul,

    Thank you for answering.

    Below is a comparison of Table 3 of Section 6.11 with our graphics board settings.

    Each parameter seems to have no problem.

    (VBP is less than 370 μs, but it seems to be the same in the example of Table 4)

    Could you teach me the image parameters you tested?

    Best Regards,

    Masa

  • 0 in reply to Masayuki Iwata
    TI__Mastermind 30600 points
    Hi Masa-san,

    I should have been clearer - I tested my Lightcrafter using your pattern sequence settings, not the video parameters you showed. From your table, it looks like your parameters are good.

    What I would recommend next is to try playing with your frame rate a little to see if there is any frame rate where the issue goes away. My computer offers fairly limited control of frame rate, so you'll have to do that testing.

    -Paul
  • 0 in reply to Paul Goedeke
    Intellectual 710 points

    Hi Paul,

    I have no time to try rate combinations.
    For example, when the bit depth is 7 bits in the pattern sequence mode, how much is the allowable value of the frequency range?
    Is it defined in DLPC 350?

    Best Regards,

    Masa

  • 0 in reply to Masayuki Iwata
    TI__Mastermind 30600 points
    Hi Masa,

    Your issue is not one that we have seen here and I am unable to reproduce it. The main culprit usually in these types of problems is the video source and because each video source is unique, it is difficult for me to debug what is going on with yours in particular.

    I don't know the allowable range for a given frequency of display, that hasn't been characterized. The technical information regarding timing is found in the DLPC350 datasheet and the programmer's guide.

    If you're able to test the Lightcrafter with a couple different computers and see if the issue persists, that would be helpful. You could also try feeding your video signal to a monitor or similar to see if the flickering occurs there as well.

    -Paul
  • 0 in reply to Paul Goedeke
    Intellectual 710 points
    Hi Paul,

    I think that no more informations will come out, so I will finish with this.
    Thanks.

    Best Regards,
    Masa