Cursor Handling in Variable Refresh Rate Displays
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Solution Overview
Problem
Variable refresh rate technologies in display systems face issues with image artifacts, such as tearing and stuttering, due to asynchronous rendering rates between graphics processing units (GPUs) and display devices, particularly when complex scenes are rendered, leading to unpredictable frame generation times and challenges in maintaining interactive cursor updates.
Innovation Solution
A method for handling cursors in variable refresh rate environments involves combining cursors with images at different positions and using a refresh timeout to ensure minimum refresh frequencies are met, allowing for dynamic adjustment of refresh rates based on cursor redraw rates and estimated image durations to prevent stuttering and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable refresh rate technology is used to synchronize with GPU rendering, then image artifacts like tearing are reduced, but cursor responsiveness deteriorates when GPU rendering is slow
Solution Approach 1:
The display refresh process is segmented into two independent paths: one for main image content (synchronized with GPU at variable rates) and one for cursor elements (refreshed at fixed high rates). This allows cursor updates to occur independently of GPU rendering speed, maintaining responsiveness without compromising image synchronization.
Solution Approach 2:
The system dynamically adjusts refresh behavior based on element type: main images use variable refresh rates matched to GPU output, while cursors use fixed high refresh rates. This dynamic differentiation resolves the contradiction by applying appropriate refresh strategies to different display elements based on their functional requirements.
2Reliability
If display refreshes wait for new GPU frames, then image stuttering is reduced, but refresh frequency drops below minimum requirements when rendering is slow
Solution Approach 1:
The system performs preliminary actions by pre-refreshing the display with previously rendered frames before new GPU frames are ready. This ensures minimum refresh frequency requirements are met while maintaining image smoothness, as the display continues to refresh at required rates using available content.
Solution Approach 2:
The system implements periodic cursor refreshes at fixed intervals independent of GPU frame arrival. This periodic action ensures minimum refresh frequency is maintained for cursor elements even when main image rendering is slow, separating cursor refresh timing from GPU synchronization constraints.
3Device complexity
If cursor is updated only when new GPU frames are generated, then rendering complexity is reduced, but cursor update rate becomes uninteractive during slow rendering
Solution Approach 1:
The cursor update mechanism is segmented from the main image rendering pipeline. Cursors are updated independently at fixed high rates regardless of GPU frame generation timing, maintaining interactivity without requiring complex synchronization with variable rendering rates.
Solution Approach 2:
A frame repetition mechanism acts as an intermediary, repeating previous frames at fixed intervals to maintain display refresh frequency. This intermediary allows cursor updates to proceed at required rates even when new GPU content is not available, bridging the gap between variable rendering and fixed refresh requirements.
Data Source
AI summary
A method, computer program product, and system for cursor handling in a variable refresh rate environment are disclosed. The method includes the steps of receiving a first image, combining a cursor at a first position with the first image to produce a first combined image, and displaying the combined image on a variable refresh rate display device. The method also includes the steps of determining that a refresh timeout associated with the variable refresh rate display device has occurred, and then, after determining that a second image has not been generated, combining the cursor at a second position with the first image to produce a second combined image for display. The logic for implementing the method may be included in a graphics processing unit or within the variable refresh rate display device itself.