I have a Smash Bros Melee setup with a low-latency display and a low-latency Wii->HDMI converter. I'd like to split the signal across two displays (so everyone can see the screen during 4-player matches), ideally with zero added latency (but up to 2ms or so of extra latency would be OK).

With analog video tech you can just physically split the signal, but I'm not sure this applies to HDMI; most splitters are active devices. Do these splitters introduce any lag (e.g. by capturing, buffering, and retransmitting packets)?

  • I don't think we're really qualified to answer this. An HDMI splitter isn't a gaming-specific device. – Frank May 31 '16 at 22:18
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    @Frank but input latency on TV's generally is a gaming specific issue. I'm not completely sure which way this falls though. – Elise May 31 '16 at 22:24
  • I wonder if HDMI splitters actually have to do any data transformation at all? Or whether they are simply one input directly electrically connected to two output (because as far as I know HDMI seems to be Master -> Client only, not the other way)? In the latter case it would mean there would be no lag at all. (EDIT): Asked over on SuperUser. – MC ΔT Jun 1 '16 at 5:10
  • hdmi is a digital communication which with higer versions often includes the function of handeling device identifiers and signal is often passed both ways in the process. ie a blueray device with v2 antipiracy protections will downscale resolution if plugged into a v1 hdmi tv or not play at all. this is why some down converters wont work with newer content. ive never seen a splitter to allow multiple tvs to run from one device usually its the other way around for tvs with many devices but limited ports...but chances is each tv would need digital seperation hence latency is likely.... – Firobug Jun 1 '16 at 10:47

I can't say definitively for all HDMI splitters because they can be implemented in different ways, but the ones that I have used all produce no input lag, even though they require A/C power.

The bigger concern for you would actually be the composite -> HDMI upconverter, because the processing that needs to be done for that could potentially produce lag. You say that it is low-latency though, so you should be good.

  • Some folks did a really fantastic analysis of this issue at meleeitonme.com/this-tv-lags-a-guide-on-input-and-display-lag. I'm using their recommended setup which introduces ~2ms lag vs a CRT (the gold standard). Were you able to measure the latency introduced by your splitters? I'm interested in achieving a lag much smaller than one frame (16.7 ms), which wouldn't be noticeable but could cause subliminal effects on timing. – Kerrick Staley Jun 1 '16 at 22:52
  • I haven't done exact latency testing, but I can attest that I have done much high-speed, high-precision gaming using this setup (including rhythm games) and have encountered no issues. – Chase Sandmann Jun 1 '16 at 23:17

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