Input Lag: Impact of Front Porch, Sync Porch, Back Porch, Blanking, Total, and Sync Polarity Settings

[m2or]

Stumbled across this thread and was wondering if these settings have any effect on input lag at all, I tried to lower and I don't understand what is better minimum timings, or VT (QFT), I want to find out which of these has the lowest latency.

[RealNC]

Stumbled across this thread and was wondering if these settings have any effect on input lag at all, I tried to lower and I don't understand what is better minimum timings, or VT (QFT), I want to find out which of these has the lowest latency.

QFT. Minimum timings don't accelerate the scanout, and thus don't affect input lag. QFT does.

[m2or]

Stumbled across this thread and was wondering if these settings have any effect on input lag at all, I tried to lower and I don't understand what is better minimum timings, or VT (QFT), I want to find out which of these has the lowest latency.

QFT. Minimum timings don't accelerate the scanout, and thus don't affect input lag. QFT does.

To get the lowest latency I need to lower the horizontal total, or raise it?

[RealNC]

To get the lowest latency I need to lower the horizontal total, or raise it?

Horizontal total doesn't matter. Only vertical total does. The higher the VT, the lower the latency. So if lowering HT allows you to use a higher VT, then just do that.

However, with that being said, don't expect any significant improvements in latency with QFT. When you run your display at its maximum refresh rate, you're already using close to the maximum VT the display can handle anyway. QFT is mostly useful when you want to run your high refresh rate (like 240Hz) display at 60Hz without VRR and use QFT, giving you the scanout speed of 240Hz while running at 60Hz. And if you're using VRR (gsync/freesync), then QFT happens automatically anyway, so you don't even need to bother. Running the display at 240Hz but enabling VRR and capping game FPS to 60 will automatically result in 60Hz + QFT with a scanout speed of 240Hz.

[m2or]

To get the lowest latency I need to lower the horizontal total, or raise it?

Horizontal total doesn't matter. Only vertical total does. The higher the VT, the lower the latency. So if lowering HT allows you to use a higher VT, then just do that.

However, with that being said, don't expect any significant improvements in latency with QFT. When you run your display at its maximum refresh rate, you're already using close to the maximum VT the display can handle anyway. QFT is mostly useful when you want to run your high refresh rate (like 240Hz) display at 60Hz without VRR and use QFT, giving you the scanout speed of 240Hz while running at 60Hz. And if you're using VRR (gsync/freesync), then QFT happens automatically anyway, so you don't even need to bother. Running the display at 240Hz but enabling VRR and capping game FPS to 60 will automatically result in 60Hz + QFT with a scanout speed of 240Hz.

there must be some correct ratio? For example, "Front Poch + Sync width = Back porch" - Front Porch and Sync Width default to 116/3 and 144/4, But I only increase the vertical setting of the back porch to 393 to get a total of 1360 is this correct?

[Espionage724]

Stumbled across this thread and was wondering if these settings have any effect on input lag at all, I tried to lower and I don't understand what is better minimum timings, or VT (QFT), I want to find out which of these has the lowest latency.

QFT. Minimum timings don't accelerate the scanout, and thus don't affect input lag. QFT does.

To get the lowest latency I need to lower the horizontal total, or raise it?

https://www.monitortests.com/blog/timin ... explained/

• Front porch, also known as sync offset, is basically padding before the sync pulse.
• Sync width is the duration of the sync pulse. The sync pulse marks the start of the next line (horizontal sync) and the next frame (vertical sync).
• Sync polarity is whether the sync pulse voltage goes up (+) or down (−). Most monitors can handle both.
• Back porch is basically padding after the sync pulse, before the start of the active pixels.
• Total is the total number of pixels including blanking.

Sounds like porches should be lowest (what good is padding?), but width sounds more important to be lowest (more padding but quicker).

1600x900@76Hz Native (PC) does 24/96 front/back porch and 80 width, while Exact does 48/80 32 (higher front porch, way less width); it looks like I'd want Exact timings or any that have the lowest width.

Anything else seemingly doesn't change much and might have minimal effect, but with Total Exact is 1760 vs Native 1800.

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