Is Black Magic SDI Output from VDMX faster or slower than HDMI?

#1

Hi, my HDMI output is often sent through an SDI converter box because I perform in larger halls and the projector is miles away, so I’m wondering if I’d see quicker response times if I bought something like the Black Magic HD Mini and output SDI directly from VDMX. Anyone have any experience with this? Here’s the box I have in mind.

https://www.bhphotovideo.com/c/product/1335021-REG/blackmagic_design_bdlkulsdminhd_ultrastudio_hd_mini_with.html

Thanks.

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#2

We suggest using a direct output from your graphics card via HDMI / DVI whenever possible compared to a BlackMagic output.

Basically in order to send video out from those boxes we have to read images back from the GPU (which is where they are processed and composited), whereas with the monitor output the GPU gets to draw directly to screen, which is ‘faster’ both in terms of latency and efficiency.

That said, this is something you may need to take into account when optimizing a setup to get a bit of extra performance, you may not even notice much difference between the output methods in normal usage.

And I can’t speak to how much latency is added by other boxes that you are using to convert from HDMI to SDI, but I suspect they are comparable.

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#3

Thanks, that’s helpful to know. The external converter SDI boxes typically add just one frame (16.6ms at 60Hz) or two at most. My main application is Image Magnification (and reaction), so every millisecond I save is worthwhile.

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