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How We Measure Input Lag: The BSN Testing Standard

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2 weeks ago

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How to measure input lagIn competitive gaming and streaming, milliseconds can decide whether your shot lands or your stream stays in sync. Every piece of hardware between your hands and your screen adds a tiny delay — what we call input lag.

At BSN, we don’t rely on manufacturer claims or “gaming mode” promises. We measure it.
 Our input lag testing standard is designed to quantify responsiveness across displays, capture cards, and audio devices — using high-speed recording, frame analysis, and latency tracking tools.

Our goal is simple: make every review consistent, transparent, and backed by real measurements — so when we say a device feels “instant,” you know exactly what that means in milliseconds.

Test Environment & Hardware Setup

Accurate latency testing starts with a controlled, repeatable setup.
 Every BSN test follows a consistent environment to ensure our results are fair, comparable, and reproducible across product categories.

🖥️ Hardware Configuration

Our current input-lag testing bench uses a balanced, high-refresh system capable of sustaining high, stable frame rates without CPU or GPU bottlenecks.

Component Model / Example Purpose
CPU Intel Core i7 / Ryzen 7 equivalent Stable frame delivery
GPU NVIDIA RTX 4070 / 4080 Consistent frame pacing and Reflex support
Memory 32 GB DDR5 Prevents buffering or scheduling delays
Storage NVMe SSD Fast data loading
Reference Display 240Hz G-Sync monitor Baseline visual latency reference
Test Display / Capture Device Device under review Subject for measurement
Audio Output External DAC + Headset Audio latency testing
Camera 240–960 fps high-speed camera Frame-accurate recording

We use a dual-output video chain — the GPU output is split via HDMI into a reference display and a test display (or capture card).
 This allows us to film both screens simultaneously for visual latency comparison.

Software & Tools

Tool Use Case
OBS Studio Capturing and monitoring video feeds
CapFrameX Frame-time logging and analysis
NVIDIA Reflex Analyzer Measuring system-level latency in supported titles
Audacity Audio waveform latency comparison
DaVinci Resolve / Premiere Frame-by-frame video analysis
Time Sleuth / HDFury HDMI signal testing (for display pass-through delay)

Tests are performed in a dark, controlled environment to minimize flicker or light interference during slow-motion recording.
 Every trial is run multiple times to ensure consistent averages and identify outliers.

Methodology

Once the testing environment is prepared, we begin the actual measurement process.
 At BSN, our input-lag analysis focuses on three measurable latency layers that together define the total responsiveness of a gaming or streaming setup.

These are the areas we test for every device:

  • Display & Visual Latency — How long it takes for a rendered frame to appear on screen.
  • Audio & Capture Latency — How much delay exists between an event and when you hear or broadcast it.
  • System & Processing Latency — The internal delay within your PC or console between frame creation and frame output.

Each test isolates one part of the latency chain while keeping the rest constant, allowing us to pinpoint exactly where responsiveness is lost or gained.

💡 BSN Principle
Our goal is simple: build a transparent, repeatable testing method that measures latency in milliseconds — not impressions — and makes those numbers meaningful to players and creators alike.

Display & Visual Latency

What It Is

Display latency, sometimes called signal or screen delay, is the time between when the GPU sends out a finished frame and when that frame actually becomes visible on the display. Even fast, high-refresh monitors or capture cards can add several milliseconds of delay from internal processing, image scaling, or pixel transitions.

Why It Matters

Every frame in a competitive title counts. If your monitor shows what’s happening even a few milliseconds late, your reactions are always behind the action.For creators and streamers, display latency also affects capture pass-through — the delay between gameplay and what appears on your recording or broadcast preview.

In short: Lower display latency means faster feedback, tighter aim, and smoother streaming sync.

How We Test

To measure visual latency precisely, we rely on a dual-display high-speed recording setup.
 Here’s how it works:

  1. Send the Same Signal to Two Screens
    • We use an HDMI splitter to duplicate the GPU’s video output.
    • One feed goes to a reference display (a known fast, low-latency monitor).
    • The other goes to the test display or capture card under review.
  2. Show a Simple Visual Change
    • The PC runs a timed test pattern, such as a white box flash or a frame counter that changes every refresh.
    • This gives us a clear visual trigger to measure from.
  3. Record Both Screens in Slow Motion
    • A high-speed camera (240–1000 fps) films both displays at once.
    • The goal is to capture the exact frame where the reference display updates and when the test display follows.
  4. Count the Frames Between Them
    • We play back the footage frame by frame in DaVinci Resolve or Premiere.
    • The number of frames between the two changes, divided by the camera’s frame rate, gives the display latency in milliseconds.
  5. Example:
     2 frames of difference at 960 fps = (2 ÷ 960) × 1000 = 2.08 ms.
  6. Repeat and Average
    • Each test is run multiple times to ensure repeatability.
    • We record both average latency and p95 latency (the worst 5% of readings).

p95 = the 95th‑percentile (worst‑case) latency.

  1. Present a Lightweight Proof Strip
    • Instead of embedding heavy video, we publish a 3-frame image strip:
      1. Frame before the change
      2. Frame where the reference updates
      3. Frame where the test display updates
    • This gives readers visual proof of the delay while keeping the page fast and clean.

How We Report

Our results are shown in milliseconds, averaged across several runs, and summarized by display mode.

Mode Avg Lag (ms) p95 (ms) Verdict
Game Mode 3.9 5.1 ✅ Instant
Standard Mode 11.6 13.2 ⚠️ Acceptable
HDR Enabled 6.4 7.0 ✅ Minor Delay

We also test common display settings such as Game Mode, VSync, and VRR to identify how each affects real-world response time.

🎯 Takeaway
The faster a screen reacts to a new frame, the closer your visuals align with your actions. At BSN, we measure latency where it matters most — the moment it appears on-screen.

Audio & Capture Latency

What It Is

Audio latency is the delay between the moment a sound event is generated by your system and when it’s actually heard through your headset, speakers, or recorded output.
 For streamers and creators, we also measure capture latency — the delay between what happens on-screen and when that same moment appears (with audio) in recording or stream software like OBS.

Why It Matters

While a few milliseconds of delay may not seem like much, audio lag quickly becomes noticeable when it doesn’t match what you see or say.
 For gamers, this means hearing a gunshot slightly after it happens on-screen.
 For streamers, it means commentary that’s out of sync with gameplay.
 And for capture setups, it can create audio-video desync that distracts viewers and complicates editing.

In short: If display latency determines what you see, audio latency defines how “in tune” your experience feels.

How We Test

We use a combination of visual cues, sound triggers, and high-speed recording to measure audio latency and AV sync.

  1. Create a Visual + Audio Event
    • We use a synchronized test — a white screen flash paired with a short tone or beep.
    • The flash and sound are triggered at the exact same time from the same source.
  2. Record It in Slow Motion
    • Our high-speed camera films both the screen flash and records the sound via the camera mic (or external mic close to the headset).
    • This allows both events to be captured in one recording.
  3. Analyze the Video or Audio Waveform
    • We import the footage or audio clip into a waveform editor like Audacity or DaVinci Resolve.
    • We identify the frame when the flash appears and the moment the tone is heard, then calculate the delay between the two.
    • Formula:

      Audio latency (ms) = (frame difference / camera FPS) × 1000
  4. Repeat for Different Conditions
    • Each device is tested under multiple modes:
      • Wired vs. Wireless connection
      • Bluetooth codec (SBC, AAC, aptX, LC3, etc.)
      • Mic monitoring (sidetone) on/off
    • This ensures consistency and highlights codec or mode-specific delays.
  5. Testing Capture Card Audio Sync
    • For capture devices, we record an AV sync test clip (flash + beep) through OBS or Streamlabs.
    • We compare the captured footage to the direct source playback.
    • The time difference between flash and sound in the recording gives us the audio-video sync offset — how much delay the card adds to captured footage.

How We Report

Device / Mode Connection Avg Latency (ms) p95 (ms) Notes
Wired Headset USB <2 <2 Practically instant
Wireless Headset 2.4 GHz 47 52 Low-latency wireless
Bluetooth (SBC) BT 183 200 Noticeable delay
Capture Card (OBS) HDMI Pass-through 32 38 AV sync offset ~1 frame

Each result includes both average latency and worst-case delay to show consistency over multiple trials.We label anything under 50 ms as “unnoticeable”, while anything over 100 ms is “noticeable in fast-paced content.”

🎯 Takeaway
Audio lag can be just as disruptive as display lag. By pairing visual and audio cues in one test, BSN measures how well your system stays in sync — ensuring your gameplay, capture, and commentary all line up in real time.

System & Processing Latency

What It Is

System latency measures the time your PC or console takes to process each frame — from the moment the CPU begins to render it to the instant the GPU outputs the finished frame.
 It’s the invisible part of input lag that happens before the frame ever reaches your monitor.

This layer includes:

  • CPU scheduling delay (game logic, draw calls)
  • GPU queueing delay (render buffer, frame pipeline)
  • Driver and synchronization overhead (VSync, G-Sync, Reflex, etc.)

Why It Matters

Even the fastest display can feel sluggish if your system’s render queue is bloated or inconsistent.
 Games that run at 300 FPS can still feel laggy if the frame pipeline adds extra delay or fluctuates wildly between frames.
 That’s why we test system and processing latency — to understand how efficiently each setup turns performance into responsiveness.

In short: More frames per second doesn’t always mean lower input lag.Stability and timing consistency matter just as much as raw performance.

How We Test

BSN uses a mix of frame-time logging and Reflex-based latency analysis to measure system delay and stability.

  1. Use a Low-Latency Benchmark or Game
    • We test using competitive titles like CS2, Valorant, or Apex Legends, where latency-sensitive design is critical.
    • All tests are run under consistent conditions (same map, scene, and load).
  2. Measure with Reflex Analyzer or CapFrameX
    • If the test system supports NVIDIA Reflex Analyzer, we record latency breakdowns:
      • PC Latency: time between CPU start and GPU output
      • System Latency: total click-to-display delay
    • On systems without Reflex support, we use CapFrameX or PresentMon to log frametime data and detect frame pacing irregularities.
  3. Analyze Frame-Time Stability
    • Beyond averages, we focus on:
      • Average Frametime (ms) — overall performance
      • p95 Frametime (ms) — worst 5% of frame delays
      • Frametime Variance (Δms) — stability of frame delivery
    • This shows how smooth or jittery the game’s frame output is, which directly affects perceived input delay.
  4. Combine with Display Latency (Optional)
    • For “click-to-pixel” latency estimation, we combine measured system latency with display latency results.
    • This provides a real-world total response time that reflects what the player actually experiences.

How We Report

Test Mode Avg Frametime (ms) p95 (ms) Variance Verdict
Reflex ON 5.8 7.1 0.4 ✅ Stable, low latency
Reflex OFF 8.6 12.9 1.7 ⚠️ Noticeable frame delay
VSync ON 10.9 15.2 2.1 ❌ Smooth but delayed
VRR ON 6.1 7.0 0.5 ✅ Balanced performance

We test each mode under identical GPU load, refresh rate, and resolution.
 Results are averaged over several 60-second runs to ensure consistency.

🎯 Takeaway
Smooth frame pacing often matters more than sheer FPS. BSN’s system-latency testing reveals how software features, sync options, and game engines influence the delay you actually feel between action and reaction.

Why Input Lag Matters

For most people, input lag is invisible — until it costs a round, a reaction, or a perfectly timed shot.

Input lag is the silent gap between your action and your system’s reaction.
 Click your mouse, press a key, swing a controller stick — your hardware, software, and display all take a few milliseconds to process that input and show the result. Those few milliseconds can make the difference between responsive and sluggish, precise and off-beat.

🎮 For Gamers

In competitive shooters like CS2 or Valorant, even a 5 ms delay can affect flick timing and recoil control.
The faster your display and system respond, the more accurately your actions line up with what you see on-screen.

🎥 For Streamers & Creators

If you use a capture card, that same delay affects what your viewers see and hear.
A small mismatch between video and sound can throw off commentary or make gameplay footage feel out of sync.

🎧 For Everyday Users

Even outside esports, input lag shapes how “snappy” your setup feels.
Menu navigation, video editing, and music production all rely on precise feedback loops between eyes, ears, and hands.

Wrapping Up

Measuring input lag isn’t about chasing numbers — it’s about understanding how hardware truly feels to use.
 Every device, from a gaming monitor to a capture card, adds its own delay to the chain. BSN’s standardized methodology breaks that chain into measurable, transparent parts: display, system, and audio latency.

By testing under real gaming conditions and publishing verifiable results, we turn milliseconds into meaningful data.
 Our goal isn’t to prove that one product is “fastest” on paper — it’s to show how consistently and reliably it responds in real play, stream, or production use.

Every BSN latency result is measured, not assumed.
Through repeatable testing and frame-by-frame analysis, we ensure that every number we publish reflects real responsiveness — not marketing claims.

quote

This is what defines the BSN standard:

  • Visible proof through high-speed recording.
  • Consistent methodology across categories.
  • Transparent reporting so readers can trust what they read.

Whether you’re tuning your setup for competitive gaming, building a dual-PC stream rig, or choosing the right monitor, BSN’s latency data gives you the same advantage we test for — confidence in every millisecond.

FAQ

1. What tools does BSN use to measure input lag?

We combine high-speed visual recording with frame-time and waveform analysis.
Our toolkit includes a 240–960 fps camera, OBS Studio, CapFrameX, NVIDIA Reflex Analyzer, Audacity, and Time Sleuth for HDMI testing.
Each setup is calibrated to ensure that only device behavior — not test gear — affects results.

2. How accurate are BSN’s input lag measurements?

Our high-speed video tests measure delays with frame-level accuracy, typically within ±1 ms of real timing.
Every trial is repeated several times to calculate average and p95 (worst-case) latency, giving results that are both repeatable and transparent.

3. Why do input lag numbers vary between reviews or brands?

Because every site measures latency differently.
Some report full end-to-end latency (from input to display), while others only measure pixel response.
BSN’s data isolates latency by category — display, system, and audio — so readers can understand where each delay originates.

4. What is considered “good” input lag for gaming?

For most fast-paced titles, under 10 ms total delay (display + system) feels instant, while 10–20 ms is still acceptable.
Anything beyond 30 ms becomes perceptible, especially in rhythm or competitive shooters.

5. Does higher refresh rate always mean lower latency?

Not always. Higher refresh rates reduce frame intervals, but true latency also depends on processing pipelines, synchronization modes, and frame-time stability.
That’s why BSN measures both refresh behavior and system responsiveness in tandem.

6. Can audio or capture latency be completely eliminated?

No — all digital processing introduces some delay.
However, with the right codec, wired connections, and optimized capture chain, latency can be reduced to levels imperceptible in real use
(<50 ms for audio, <1 frame for capture).

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