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What software do people use for frame accurate video display with lightcrafter DMDs?

Alexander Sludds
Prodigy 120 points
Other Parts Discussed in Thread: DLP4500

Hi everyone,

I have an application that requires frame accurate display of data (which I have encoded in video format, but really represent matricies with patterns) onto the DMD. The application has precise timing requirements which I wish to meet. In addition, the application requires two DMDs transmitting seperate data which are in-sync with each other timing-wise.

So far I have tried using open-cv with a timing look enclosing it, but this is not precise enough and seems to load the video into CPU memory/RAM before sending it to the DMD for display.

I have also tried using libvlc/python-vlc with a tkinter to display the window. This seems to have much better timing performance, but I have a lot of software problems trying to have windows display/ start and stop in sync with each other.

If possible my language of choice for this application is python, because it integrates into other code I have for post-processing sensor data.

Thank you,

-Alex

  • 0
    TI__Mastermind 20045 points

    Hello Alex,

    Could you confirm what specific DMD and corresponding controller you are utilizing? Our Light Control products have the ability to synchronize using external input and output triggers which may be useful. For very precise timing requirements FPGAs may be used to interface with the DMD controller. 

    Please let me know your product though and I can try to point you in the right direction.


    Thanks,

    Kyle 

  • 0 in reply to Kyle Rakos
    Prodigy 120 points

    Hi Kyle,

    I am using the DLP3000 and DLP4500 evaluation boards. I am aware of the DMD's triggers, however, I still need to display large amounts of distinct data on the DMD at 60Hz, which is why I am using the HDMI ports. However, I am unsure how to actually display video over the HDMI port such that if the video is 60Hz it displays on the DMD at 60Hz without any dropped frames.

    Any help would be appreciated.

    Thank you,

    -Alex

  • 0 in reply to Alexander Sludds
    TI__Mastermind 20045 points

    Hello Alex,


    What graphics card are you using? It is possible some professional or high end graphics cards have some libraries that may assist with precise video timing. Alternatively, an FPGA may be needed if you need even more precise control. 


    Thanks,
    Kyle 

  • 0 in reply to Kyle Rakos
    TI__Mastermind 30875 points

    Hi Alex,

    From your description of the problem i interpret as follow -

    There are two LightCrafter hardware.

    Both are controlled through software - for Start/Stop.

    Problem - Cannot synchronize.

    The way LightCrafter hardware communicates with the PC is via TCP i/f - TCP over USB to be precise. Using this method there is always going to be timing issues if you were to send command command to one after other. The delays coming from software sending the TCP packets. 

    My recommendation is the following - Always keep the hardware in start state. Never send the [Stop] command. Rather you from the front-end you can stop sending the VSYNCs or video to the hardware. The LightCrafter waits indefinitely in start state until next video (VSYNC) come. 

    So don't use software start/stop, send start once, then control video signal going to the hardware. 

    Hope this helps.

    Regards,

    Sanjeev

  • 0 in reply to Sanjeev
    Prodigy 120 points

    Hi Sanjeev,

    That's actually really helpful, I didn't realize I could just control the vsync signal and the DMD's would trigger off of it.

    Do you have software recommendations for how I can control the vsync signal? I have an Nvidia GTX 1050 on the desktop that is controlling these if that makes a difference.

    Thank you

  • 0 in reply to Alexander Sludds
    TI__Mastermind 30875 points

    Hi Alexander,

    Unfortunately we don't have much details on how this particular graphics card can be configured. You may want check with the manufacturer for further help.

    I will be closing this ticket for now. Feel free to get in touch to us if you need further assistance,

    Thanks,

    Sanjeev