Graphical Display Latency Measurement via Embedded Timestamp
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Solution Overview
Problem
Existing methods for measuring graphical display output latency are inadequate as they include other latency factors, such as input device latency, and do not accurately isolate graphical latency, which is crucial for safety applications like automotive systems where low latency is essential for timely driver response.
Innovation Solution
A system and method that utilize a processor to generate a timestamp, transmit it to a GPU for rendering a display frame with graphical symbols, capture these symbols with a camera, and compare them to a time reference to determine graphical output latency, allowing precise measurement of graphical latency without confounding factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods (high-speed camera counting frames between mouse click and display update) are used to measure latency, then a measurement system can be established, but the measurement includes input device latency along with graphical latency, making it impossible to isolate graphical latency alone
Solution Approach 1:
The patent extracts only the graphical latency component from the total system latency by using a timestamp embedded directly in the graphical frame. The processor generates a timestamp, embeds it in the frame, and the camera captures this timestamp to measure only the graphical processing and display time, excluding input device latency and other system delays.
Solution Approach 2:
The patent introduces a timestamp as an intermediary element that is embedded in the graphical frame. This timestamp serves as a mediator between the processor and the camera measurement system, allowing precise tracking of when the frame was generated versus when it was displayed, thereby isolating graphical latency from other system latencies.
2Measurement precision
If existing methods (comparing test display with control display using stopwatch and photograph) are used, then a measurement system can be established, but the method measures time lag between displays rather than actual graphical output latency and does not account for complete frame display time
Solution Approach 1:
The patent applies preliminary action by embedding the timestamp in the graphical frame at the source (processor/GPU) before the frame enters the display pipeline. This ensures that the timestamp represents the exact moment the frame was generated for display, allowing measurement of the complete frame display time from generation to actual visual output.
Solution Approach 2:
The patent replaces the mechanical stopwatch method with an electronic timestamp embedded in the digital frame. This substitution eliminates the need for manual timing and photograph comparison, providing automated, precise measurement of graphical output latency including complete frame display time.
3Measurement precision
If industrial-grade high-speed cameras are used to capture display frames for latency measurement, then precise measurement can be achieved, but the system cost and complexity increase significantly
Solution Approach 1:
The patent uses a conventional camera instead of an expensive industrial-grade high-speed camera. The timestamp embedded in the frame serves as a disposable marker that can be captured by standard cameras, eliminating the need for specialized expensive equipment while maintaining measurement precision.
Solution Approach 2:
The patent creates a visual copy of the timestamp within the graphical frame itself. This embedded timestamp copy can be captured by any camera that can read the display, replacing the need for specialized cameras. The timestamp information is copied into the visual domain, making it accessible to conventional imaging devices.
Data Source
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AI summary
The present invention concerns a method for measuring the latency of a graphical display output, comprising the following steps:- obtaining, by a processor (5), a time value; - generating, by the processor (5), a time stamp based on the time value; - transmitting, by the processor, the time stamp to a graphics processor unit (7), GPU, rendering, by the GPU (7), a display frame including at least one graphical symbol being based on the time stamp; providing the rendered frame including the at least one graphical symbol to at least one display (10a, 10b); - capturing, by at least one camera (12), at least a portion of the display comprising the at least one graphical symbol (18, 20) of the time stamp;-determining from the at least one captured graphical symbol the rendered time stamp; and- comparing the rendered time stamp with a time reference for obtaining the latency of the graphical display output.