OSSC Pro: Does the OSSC Pro have more input latency at 2560x1440p than 1920×1080

[spacetime66]

I was testing the input lag on my LG CX 55” OLED55CXPUA with a Time Sleuth set to 240p out mode going through my OSSC Pro in A-LM mode with 2560×1440 HDMI out and the measured input latency at the middle of the screen measure about 21 ms where as with A-LM 1920×1080 HDMI out it measures about 13ms and according to Rtings LG CX review that both 1080 and 1440p @ 60hz should both be at about 13ms and am wondering if it’s the OSSC Pro that is laggier at 1440p or it just my TV (latest firmware)…

Can anyone confirm that the OSSC Pro in A-LM mode that 1440p and 1080p HDMI out has the same or different latency?

Thanks in advance

[Zacabeb]

While @marqs can give a more accurate answer, my understanding is that since A-LM only uses a limited number of input lines for buffering, it shouldn’t cause much of a delay. The specs at https://junkerhq.net/xrgb/index.php?title=OSSC_Pro#Getting_started state a maximum latency of 60 lines, which would equate to 3.8 ms assuming a line length of about 64 µs. In practice it’s probably much lower.

[marqs]

There should be no major difference between them unless there is some calculation issue in the firmware. Many TVs are optimized to reduce latency only in common modes like 1080p and 2160p.

[spacetime66]

I guess the LG CX TVs got worse at 1440p with firmware updates because according to the Rtings review on 06/15/2021 the input lag between 1080p, 1440p and 4K were virtually identical at about 13ms in the middle of the screen in game mode. https://www.rtings.com/tv/reviews/lg/cx-oled

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