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Inconsistent refresh rate with vsync_adjust=2
Posted: Wed Jul 01, 2020 6:23 pm
by Lisko
Hi I noticed a strange behavior with some cores on my 4k samsung tv with vsync_adjust=2. When starting some cores like megacd, genesis, neogeo or nes I see the picture flashing twice and in the upper left corner of the screen where it shows the infos on core and display resolution and refresh rate, I see that there is a mismatch between core and display refresh. For example on neogeo the refresh rate listed is 59.6 instead of 59.2 but I can't notice stuttering though. Another curious thing is that if I reset the core using osd then the frequencies will match. Using vsync_adjust=1 the frequencies match with no problem and the picture only flash once during refresh rate switching. What I would want to know is if the problem is only cosmetic maybe related to the odd double switching my tv does with vsync_adjust=2 or if I have to reset the core every time to assure correct refresh rate. Thanks.
Re: Inconsistent refresh rate with vsync_adjust=2
Posted: Wed Jul 01, 2020 6:40 pm
by Grabulosaure
The PLL takes a few seconds to tune when vsync_adjust=2 is selected. During that time frequency is varying a lot and your TV may show incorrect frequency.
Here is an illustration :
https://www.youtube.com/watch?v=veRuXe2wN0g
Re: Inconsistent refresh rate with vsync_adjust=2
Posted: Wed Jul 01, 2020 8:03 pm
by DamnBrrd
Lisko, what is the model of your Samsung 4k tv? It would be useful for other people to know since it looks like it handles vsync_adjust=2 well (after the initial flashing). Thanks!
Re: Inconsistent refresh rate with vsync_adjust=2
Posted: Wed Jul 01, 2020 9:25 pm
by Lisko
DamnBrrd wrote: ↑Wed Jul 01, 2020 8:03 pm
Lisko, what is the model of your Samsung 4k tv? It would be useful for other people to know since it looks like it handles vsync_adjust=2 well (after the initial flashing). Thanks!
Samsung QE49Q70RATXZT bought last year.
Yes, well it's not my TV but the mister itself that shows the wrong frequency. Maybe the code that picks the frequency to be shown needs to wait a little longer for pll to stabilize.
Re: Inconsistent refresh rate with vsync_adjust=2
Posted: Fri Jul 03, 2020 4:34 pm
by PikWik
i have the same TV (Samsung Q70R) and what youre describing is cometic, i get the same double flash starting a core/game when in vsync_adjust=2 and only one flash as it syncs the refresh rate in vsync_adjust=1.
also, one thing ive noticed when in vsync_adjust=2, i dont hear the beginning nintendo bing/sound/tone in the super mario world intro screen if i have vsync_adjust=2 enabled, where if i have vsync_adjust=1 enabled, i hear the beginning nintendo sound/tone everytime.
now at first, i was super concerned with playing with low lag mode on all my games, but after noticing small graphical glitches/tears and weird pixel noise every once in a while, i decided to just enable "match core frequency" and all my games have been glitch free with butter smooth scrolling.
i do quite enjoy being able to play these FPGA cores integer scaled to proper HD on a big screen. while its not a classic CRT in all its analog glory, the trade off of having an HD upscale with gorgeous colors at 1 frame of input lag (my TV's game mode has 14ms of input lag), theres really no reason for me to lug around a smaller TV to play retro games on.
i have a CRT, SNES, and an SD2SNES, and i still prefer to play retro on my mister. FPGA is just that good
Re: Inconsistent refresh rate with vsync_adjust=2
Posted: Mon Jul 06, 2020 8:40 am
by Lisko
PikWik wrote: ↑Fri Jul 03, 2020 4:34 pm
i have the same TV (Samsung Q70R) and what youre describing is cometic, i get the same double flash starting a core/game when in vsync_adjust=2 and only one flash as it syncs the refresh rate in vsync_adjust=1.
also, one thing ive noticed when in vsync_adjust=2, i dont hear the beginning nintendo bing/sound/tone in the super mario world intro screen if i have vsync_adjust=2 enabled, where if i have vsync_adjust=1 enabled, i hear the beginning nintendo sound/tone everytime.
now at first, i was super concerned with playing with low lag mode on all my games, but after noticing small graphical glitches/tears and weird pixel noise every once in a while, i decided to just enable "match core frequency" and all my games have been glitch free with butter smooth scrolling.
i do quite enjoy being able to play these FPGA cores integer scaled to proper HD on a big screen. while its not a classic CRT in all its analog glory, the trade off of having an HD upscale with gorgeous colors at 1 frame of input lag (my TV's game mode has 14ms of input lag), theres really no reason for me to lug around a smaller TV to play retro games on.
i have a CRT, SNES, and an SD2SNES, and i still prefer to play retro on my mister. FPGA is just
that good
I just got to your same conclusion. Having already a tv with such a low lag vsync_adjust 2 doesn't add much to 1 mode. I did some simple tests with manual lag test of the 240p test suite and I got the exact same results of about ~2.xx frames with both. My reflexes are already at their limits I suppose and in 1 mode I notice more smoothness too, maybe our tv doesn't like unbuffered mode that much either.