Source Buffer Swapping for Low-Latency Display Refresh
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Screen tearing and judder occur when the refresh rate of an electronic display is not synchronized with the graphics processing unit (GPU), leading to disjointed content and a negative viewing experience.
Innovation Solution
Implementing immediate source buffer swaps during the display of older image data to enable higher refresh rates, allowing the GPU to process frames faster than the display can show them, thereby reducing latency and judder while accepting a momentary screen tear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the GPU processes frames at a higher rate than the display can show them, then the refresh rate is improved and latency is reduced, but screen tearing occurs
Solution Approach 1:
The patent applies preliminary action by pre-rendering multiple frames in advance (e.g., frames N, N+1, N+2) before they are needed for display. The system maintains a queue of pre-rendered frames and uses them proactively to keep the display pipeline full, ensuring that when a frame becomes available, it can be displayed immediately without waiting for the next vertical sync interval. This resolves the contradiction by allowing high GPU frame rates while preventing screen tearing through proactive frame preparation and deterministic swap timing.
2Object-affected harmful factors
If vertical synchronization is implemented to maintain display-GPU sync, then screen tearing is reduced, but the refresh rate is throttled and judder increases
Solution Approach 1:
The patent applies dynamics by making the frame presentation strategy adaptive rather than fixed. The system dynamically switches between different frame presentation modes (e.g., VSync mode, VSyncOff mode, or intermediate modes) based on real-time conditions such as GPU frame generation rate, display capability, and content type. This allows the system to maintain synchronization and prevent tearing when needed while enabling higher refresh rates and reducing judder when conditions permit, thus resolving the contradiction between screen tearing prevention and refresh rate maintenance.
3Object-affected harmful factors
If the display waits for the next frame to display newest image data, then screen tearing is avoided, but latency increases
Solution Approach 1:
The patent applies preliminary action by pre-rendering multiple frames (N, N+1, N+2) in advance and storing them in a queue. When the display needs to present a frame, it can proactively select from the pre-rendered queue rather than waiting for the GPU to generate the next frame. This allows the system to display the newest available frame immediately, reducing latency while maintaining synchronization through deterministic swap timing at predetermined moments (e.g., vertical sync intervals or during blanking periods), thus resolving the contradiction between latency reduction and screen tearing prevention.
Data Source
AI summary
A GPU may process images at a faster rate than the electronic display can display them, causing the rendered image data to be several frames ahead of the electronic display. If it is determined that the GPU is ahead of the display, a more recent frame may be displayed on the electronic display during display of a present image frame by swapping from a first source buffer including the older image data to a second source buffer including the newest image data received from the GPU. While swapping source buffers mid-frame may result in a momentary screen tear, in some applications a momentary screen tear may be desirable if greater refresh rate is enabled, lag/latency is reduced or eliminated and screen judder is mitigated or prevented.