PSA: your TV may have way lower lag over VGA port than HDMI

The place for all discussion on gaming hardware
Post Reply
User avatar
xeos
Posts: 167
Joined: Thu Oct 20, 2016 10:38 pm
Location: San Diego, California

PSA: your TV may have way lower lag over VGA port than HDMI

Post by xeos »

I just finished testing an older VIZIO tv, and the TV went from having the worst input lag I've ever tested to being one of the fastest, with one "simple" change. No, not turning on game mode, but switching from the HDMI port to the VGA port. We are talking 47ms faster over VGA. That's enough you could tell the difference without a hardware lag tester, although I used a piLagTesterPRO to get exact numbers:

https://alantechreview.blogspot.com/202 ... t-lag.html

To be honest, this is the first time I've seen it make that kind of difference, but if you have an older Vizio TV it's definitely worth trying.

I have another Vizio TV that has super low input lag (~3ms) in 1080p but is at least 25ms slower in every other mode.

The only other tv I've ever seen where input choice matters is a Sony TV where component video was 9ms faster than HDMI.

But I haven't made an extensive test of this on other displays. Obviously, it's worth more testing, and I'll be doing that in the future, though most of my published TV tests were done on sets I've since gotten rid of (I don't have enough space for 20 tvs in my house!), so it will be a while before I have much data on how wide-spread this phenomena is.
BONKERS
Posts: 417
Joined: Thu Dec 11, 2014 10:41 am

Re: PSA: your TV may have way lower lag over VGA port than H

Post by BONKERS »

Those old Vizios in particular are pretty terrible. They process signals over HDMI in a weird way that add lag and makes the picture look worse. You can force them into a proper 0-255 4:4:4 PC mode that has lower lag over HDMI, but depending on the model it may not work consistently. Even on the VGA port it can be hit and miss, sometimes it will display the signal properly and other times it won't.
You'd think the stuff that has made it over to their 4k sets (proper 4:4:4 support, or properly supporting an RGB mode without overprocessing the signal and adding lag) would trickle down into the current 1080p models but it hasn't. I bought one a year or two ago and tried it and still the same crap. Had to return it.
headlesshobbs
Posts: 386
Joined: Sun Jul 04, 2010 11:14 pm

Re: PSA: your TV may have way lower lag over VGA port than H

Post by headlesshobbs »

I think there was a difference in the way computer lcd's accept a vga as opposed to how HDTV's do it. Whenever I had a hookup, the contrast levels ended up being off and any resolution differences were either scaled improperly or not supported.

I guess right now most HDTV's are down to just the hdmi port, but that means having to deal with whatever you can put up with while having to do the vga to hdmi conversion yourself.
"Don't HD my SD!!"
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: PSA: your TV may have way lower lag over VGA port than H

Post by kitty666cats »

headlesshobbs wrote:I think there was a difference in the way computer lcd's accept a vga as opposed to how HDTV's do it. Whenever I had a hookup, the contrast levels ended up being off and any resolution differences were either scaled improperly or not supported.

I guess right now most HDTV's are down to just the hdmi port, but that means having to deal with whatever you can put up with while having to do the vga to hdmi conversion yourself.
The Monoprice VGA to HDMI (non-scaling unit that NoAffinity has found to work great with GBS Control) units are pretty solid from the experiences I have had so far. The model number starts with a 'LK' or 'LKV', so I assume they are originally manufactured by Lenkeng... anyhoo, I can vouch for those being worth a shot!
headlesshobbs
Posts: 386
Joined: Sun Jul 04, 2010 11:14 pm

Re: PSA: your TV may have way lower lag over VGA port than H

Post by headlesshobbs »

That's the black box right? I used to pair that with my HDBOX pro and ega/vga scaler back in the early days.

You can also hook up a yuv component input and your tv should be able to pick it up at native (unknown?) resolution, but there's chroma shift.
"Don't HD my SD!!"
User avatar
xeos
Posts: 167
Joined: Thu Oct 20, 2016 10:38 pm
Location: San Diego, California

Re: PSA: your TV may have way lower lag over VGA port than H

Post by xeos »

BONKERS wrote:Those old Vizios in particular are pretty terrible. They process signals over HDMI in a weird way that add lag and makes the picture look worse. You can force them into a proper 0-255 4:4:4 PC mode that has lower lag over HDMI, but depending on the model it may not work consistently. Even on the VGA port it can be hit and miss, sometimes it will display the signal properly and other times it won't.
You'd think the stuff that has made it over to their 4k sets (proper 4:4:4 support, or properly supporting an RGB mode without overprocessing the signal and adding lag) would trickle down into the current 1080p models but it hasn't. I bought one a year or two ago and tried it and still the same crap. Had to return it.
The picture looked equivalent in VGA and HDMI - both equally good, with minimal aliasing and cropping. Definitely in the top quartile of the sets I've tested so far.

Out of curiosity, how did you force a proper 0-255 4:4:4 PC mode on yours?
User avatar
NoAffinity
Posts: 1018
Joined: Mon May 07, 2018 5:27 pm
Location: Escondido, CA, USA

Re: PSA: your TV may have way lower lag over VGA port than H

Post by NoAffinity »

I've noticed a trend, through research of various older screens, of a "game mode" being forced on the vga input...or maybe it's just more of a deliberate lack of processing. Either way, if I'm ever using a screen that has a vga input, I will default to that, and then also try to find a "game mode" setting in the options, to try to minimize the screens influence over the signal as much as possible.

Sent from my SM-G955U using Tapatalk
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: PSA: your TV may have way lower lag over VGA port than H

Post by kitty666cats »

headlesshobbs wrote:That's the black box right? I used to pair that with my HDBOX pro and ega/vga scaler back in the early days.

You can also hook up a yuv component input and your tv should be able to pick it up at native (unknown?) resolution, but there's chroma shift.
Yeah, kinda a matte black and flat on the top and bottom with rounded edges / flat on the ends where the connectors are :)
User avatar
xeos
Posts: 167
Joined: Thu Oct 20, 2016 10:38 pm
Location: San Diego, California

Re: PSA: your TV may have way lower lag over VGA port than H

Post by xeos »

kitty666cats wrote:
headlesshobbs wrote:
The Monoprice VGA to HDMI (non-scaling unit that NoAffinity has found to work great with GBS Control) units are pretty solid from the experiences I have had so far. The model number starts with a 'LK' or 'LKV', so I assume they are originally manufactured by Lenkeng... anyhoo, I can vouch for those being worth a shot!
I only have one sample to judge by but the dirt cheap hdmi->vga adapter I bought works fine, no evidence of signal loss. it's possible that it's transmitting a reduced luminance range, but if so the TV has automatically detected that / assumed it by default and so the blacks and white's are full contrast.

this is the one I ordered. took forever to get here (usa).

https://www.aliexpress.com/item/4001200 ... 4c4d2gu3Bg
User avatar
xeos
Posts: 167
Joined: Thu Oct 20, 2016 10:38 pm
Location: San Diego, California

Re: PSA: your TV may have way lower lag over VGA port than H

Post by xeos »

NoAffinity wrote:I've noticed a trend, through research of various older screens, of a "game mode" being forced on the vga input...or maybe it's just more of a deliberate lack of processing. Either way, if I'm ever using a screen that has a vga input, I will default to that, and then also try to find a "game mode" setting in the options, to try to minimize the screens influence over the signal as much as possible.

Sent from my SM-G955U using Tapatalk
I doubt it's a game mode per se. What exactly is going on is hard to say, but here's one idea.

The signal path is definitely going to be different with a VGA input since it's analog but not the same as yPrPb. For that reason additional circuitry is required. I'm guessing (entirely guessing!) that what's happening is rather than go with the simplest possible circuit that just converts vga into a format that the regular display engine can use, they went with a mass-produced all in one chip that handles most of the calculations required to go all the way from VGA to voltages sent to the LCD. Probably a chip meant for monitors, and as most of us know monitors are much lower lag than TVs because of the lack of all the image "improvements".

Just a theory, IDK how realistic it is. But mass-produced generic chips are definitely cheaper than lower-volume custom ones, even if they would be much smaller, so it's not crazy.
User avatar
xeos
Posts: 167
Joined: Thu Oct 20, 2016 10:38 pm
Location: San Diego, California

Re: PSA: your TV may have way lower lag over VGA port than H

Post by xeos »

I just checked another Vzio from almost the same era (https://alantechreview.blogspot.com/202 ... t-lag.html) and input lag is identical under VGA and HDMI. Interestingly the display has fantastically low input lag, just 2.5ms at the top, but only in native 1080p. it's actually the fastest TV I've ever measured, out of 34 displays (some of those are computer monitors, which come very close to the vizio).

so even within a manufacturer AND overlapping in-store availability the results can be totally different.
Post Reply