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TMS320DM8148: Video Stitching

Jason Chapman16
Prodigy 80 points
Part Number: TMS320DM8148

Hi There,

We've got an existing DM8148/68 design that is handling all of our encode / decode needs. Now we'd like to see if it's possible to use this part to perform live video stitching of multiple sources. Is it possible to use the DSP, SGX530, etc. to perform this task?  Or are they simply not powerful enough to handle it. 

Even if we were able to get a demonstrator with multiple standard definition sources it would be useful.

Thanks in advance!

Jason

  • 0
    TI__Guru**** 170625 points
    Hi Jason,

    Below you can find some Q&A that might be in help to you.

    [Question] Are there practical limitations outside of the 165MHz pixel clock (i.e. 165MHz pixel clock could imply 5MP at 33 FPS input and 16MP at 10 FPS and assuming we have sufficient DDR BW)? Can any of the IPIPE be used for processing at these large resolutions or would it be limited to pass through?

    [Answer1] regarding IPIPE processing, we are probably not going to expose the processing capability in the broad market on DM814x and just use it for pass-through.

    [Answer2] HDVPSS maximum input video supported is WUXGA (1920x1200@60fps). Maximum line width supported is 1920 pixels. Maximum height is 4k I believe. It can’t display or operate on larger images


    [Question] Could you explain further the maximum input support – and why we cannot send larger frame sizes (obviously at low fps as limited by pixel clock) to DDR and using frame decimation (i.e. horizontally splitting, and possibly even vertically splitting) to achieve high resolution images that can be stitched together?

    [Answer] There are many line buffers inside the HDVPSS which are set with a maximum width of 1920. You can’t go over that. Generally speaking, the height is not limited by buffers but by counters which are tracking width and height. The other limitation is that the video inputs are 420/422, not RGB. There are graphics inputs which support RGB, but these only go to display. Not sure what input format you are wanting. If the idea is to use HDVPSS to do memory to memory operations for scaling and such, you could break the input source into multiple images and stitch them back together. If the idea is to take a big image, break it up and downscale to get an overall size for display (max 1920x1200), you could do that.

    [Question] Ignoring the display and processing side of things though, can the input be used to simply dump the raw image data into memory for large imagers?

    [Answer] The DMA is also limited by the line buffering.

    [Question] Does it mean that you can not connect gluelessly a CMOS sensors that ouputs RGB bayer pattern like it was possible on the VPSS of the DM3xx/DM6xxx devices?

    [Answer] The statement above was with regards to video inputs from DDR, not external video inputs. VIN[0] can accept single-channel 16/24-bit (YCbCr/RGB) video or dual-channel 8-bit (YCbCr) video. VIN[1] can accept single-channel 16-bit (YCbCr) video or dual-channel 8-bit (YCbCr) video. So, DM816x can support one RGB input.

    Check also below e2e thread and links:

    e2e.ti.com/.../392756

    processors.wiki.ti.com/.../TI81XX_PSP_04.04.00.02_Feature_Performance_Guide

    processors.wiki.ti.com/.../TI811X-HDVPSS-01.00.01.44_Feature_Performance_Guide


    Note that DM816x/DM814x devices software and drivers are supported only by 3rd parties, check below e2e posts:

    e2e.ti.com/.../660422

    e2e.ti.com/.../622094

    Regards,
    Pavel