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DLP9000: Video pattern mode sync (DLPC900 GUI)

Part Number: DLP9000
Other Parts Discussed in Thread: DLPC900

Hello,

 

We intend to project the blue patterns and red patterns intermittently using video pattern mode. Specifically,  we have 1800 frames of RGB images that need to be projected as blue and red images in a row at 60HZ.  Several steps are listed below to explain what we did to achieve our goal.

 

First, we create the pattern sequence on the DLPC900 GUI under video pattern mode. The green channel and red channel are used to control the color of the projected images, as shown in the attached figure. For our case, each image projecting time is 1/ 60 =16667 us, that is to say, the exposure time will be set to 16667 us and the dark time is 0 us for both of the channels. Then each frame of the image will be exposed to 16667 us.

Second, the 1800 frames of images are saved as a 30s duration video in 60 frames/second as the external video source. And we use the PPT as the video-playing media to connect to the DMD via Displayport.

Third, we click the Start button in the DLPC900 interface (see attached image) and start the video (in PPT) at the same time manually. We expect that the output images will follow the sequence that we designed but apparently the result is not good due to the synchronization issue.

 

overall, the question is how to synchronize the video source and patterning implementation? in other words how can we make sure that the starting time of the pattern and the starting time of the video playing is the same? We know that the PPT is not an ideal playing media in our case, but we are wondering if is there any other video-supporting software that can be used to link with the DLPC900 GUI to start the video source and run the pattern program at the same time?

Looking forward to hearing from your side. Thanks!

 

Best regards,

Bin

  • Hi Bin,

    I have notified one of our DLPC900 experts of your inquiry and they will get back to you shortly

  • Hello Bin,

    The very first thing I would try is shortening the display time very slightly (about 5 us).  There is a little latency/overhead and this could cause Sequence Abort errors.

    I presume that you are using the Green and Red LED Enables.

    NOTE:  It is not necessary to pack the Red bits for the second frame.  If it is easier you can always pack them into the Green bits for each frame.  It is the color selected that determines which LEDs the Enable will turn on.  For example this sequence:

    will show the 8 bits in the green buckets in Frame 0 with the green LED enabled.  Frame 1 will show the 8 bits in the green bucket with the red LED enabled, and in my example in frame 2 it will show the 8 bits in the green bucket with the blue LED enabled.  The bits are just data.  

    Also if you want you can set Trigger 2 out to only show up once per the sequence defined, rather that every frame (i.e. with each sync)  

    Fizix

  • Hello again Bin,

    After understanding better what you are attempting to accomplish, There is not a way for the DLPC900 system to distinguish which video fram is intended for blue and which frame is for red since the stream is continuously coming from the video card of your PC/laptop.

    Instead I would suggest showing both blue and red for 1/2 of each frame time, so that each frame contains both.  If you need the full 16.66 ms of exposure, then repeat each frame twice so that you will show blue + red patter 1, then show it again.  The total exposure time across the two frames will be 16.66 ms for each color just as before.  In this way you will pack both colors into each frame and repeat the frame twice.

    Here is an example of how this would be built in the Video Pattern Mode tab:

    Notice that there is only one frame change (magenta circle) and the time for each color is 8.33 ms (purple circle - 8330 us) which is half a frame for each color.  In your video pack the data for blue pattern 1 and red pattern 1 into frame 1 and repeat the same data for frame 2.  Repeat this until you have packed all 1800 frames.

    NOTE:  If you do not need an 8 bit sequence and only need one bit of data for each pattern then you can do one of the two following ways.

          

    It will show each bit with the color selected in the color bar for 1/2 of the frame time.  It does not matter which bits you pack them in to so long as it is consistent.  So in the left image the video frame is packed with the blue data into G0 and the red data into R0.  In the second it has the blue data in G0 and the red data packed into G1.  The result will be the same.  The bookkeeping in the G0, G1 example may be simpler.

    Fizix