Stale Video Detection for Mismatched Camera Display Rates

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Solution Overview

Problem

Video systems in vehicles often present stale images due to mismatched frame rates between cameras and displays, posing safety risks.

Innovation Solution

A system comprising a camera, buffer, display, and controller that assigns hash values to images, maintains a counter, and detects stale images based on counter values to prevent their display or recording, even with varying frame rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the display frame rate is increased to provide smoother visual output, then display quality is improved, but the risk of presenting stale video increases because the display may advance to a new frame before a new image is received from the camera

Engineering Contradiction:
Improvedisplay frame rateVSAvoidstale video risk
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The system performs preliminary actions by pre-loading multiple frames into a buffer before they are needed for display. The buffer stores multiple camera frames in advance, allowing the display to access pre-fetched frames without waiting for new camera data, thus preventing stale video while maintaining high frame rates

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The buffer acts as an intermediary between the camera and display, decoupling their different frame rates. It receives frames from the camera at one rate and supplies frames to the display at a different, higher rate, eliminating the direct conflict between camera capture rate and display refresh rate

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If a simple frame repetition detection method is used, then device complexity is reduced, but false detection occurs when the frame rate of the display is greater than that of the camera

Engineering Contradiction:
Improvedetection method complexityVSAvoidstale video detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system implements feedback by continuously monitoring the actual frame rate at which new images are received from the camera and comparing it against the display frame rate. This feedback loop allows the system to dynamically adjust buffer management and detection thresholds, reducing false positives while maintaining accurate stale video detection

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The detection mechanism is made dynamic by adjusting detection criteria based on real-time frame rate conditions. When the display frame rate exceeds camera frame rate, the system modifies its detection algorithm to account for expected frame repetitions, preventing false detection while maintaining accuracy

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If the buffer stores multiple frames to accommodate variable camera frame rates, then adaptability is improved, but memory requirements increase

Engineering Contradiction:
Improveframe rate adaptabilityVSAvoidbuffer memory capacity
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The system applies partial action by buffering only the minimum number of frames necessary to accommodate the highest expected frame rate ratio between display and camera. Rather than buffering all possible frames indefinitely, it maintains a optimized buffer size that provides sufficient adaptability while minimizing memory consumption

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4364401B1Stale video detection
Publication Date: 2025.08.06 GENTEX CORP
  • EP4364401B1 patent drawingFigure 1

AI summary

A device and a corresponding system are disclosed. The device may comprise a display. Additionally, the device and/or system may be operable to detect stale images. Further, the stale images may be detected in devices and/or systems where incoming images—such as from an imager—are received at a frame rate different than that of the display. A controller may detect the stale images by assigning hash values to images of each frame displayed by the display; storing novel hash values in a memory; and maintaining a counter. The counter may be maintained such that assigning a repeat hash value increments the counter by one and assigning novel hash values resets the counter to zero. Further, the stale images may be determined based, at least in part, on the counter value.