Cloud Gaming Video Scan-Out at Flip-Time for Lower Latency
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Solution Overview
Problem
Cloud gaming systems face high latency and instability due to processing times at the server and client, frame encoding delays, and clock drift between server and client VSYNC signals, affecting the smoothness of video display.
Innovation Solution
Perform high-speed or early scan-out operations at the cloud gaming server by scanning video frames and user interface features line-by-line into input buffers and compositing them into a modified frame, starting at the flip-time of the video frame, to reduce one-way latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If scan-out operations are performed at traditional timing (after VSYNC), then display synchronization is maintained, but one-way latency increases
Solution Approach 1:
The patent performs scan-out operations at flip-time, which is before the traditional VSYNC timing. This preliminary action allows the video frame to be scanned out and encoded earlier in the processing pipeline, reducing the one-way latency from server to client without compromising display synchronization through compensating timing adjustments at the client side.
2Productivity
If frame encoding is delayed to maintain synchronization, then display stability is improved, but processing speed decreases
Solution Approach 1:
The patent performs scan-out and encoding operations in advance at flip-time rather than waiting for VSYNC. This preliminary processing allows the video frame to be prepared earlier, improving processing speed and reducing latency while maintaining display stability through timing compensation mechanisms.
3Loss of time
If scan-out operations are accelerated, then latency is reduced, but processing complexity increases
Solution Approach 1:
The patent accelerates scan-out operations by performing them at flip-time instead of waiting for VSYNC. This time-based optimization reduces latency by utilizing otherwise idle processing time during frame composition, without requiring additional hardware complexity or fundamentally changing the processing architecture.
Data Source
AI summary
A method for cloud gaming. The method including generating a video frame when executing a video game at a server. The method including performing a scan-out process by scanning the video frame scanline-by-scanline and one or more user interface features scanline-by-scanline to one or more input frame buffers, and compositing and blending the video frame and the one or more user interface features into a modified video frame. The method including scanning in the scan-out process the modified video frame to an encoder at the server scanline-by-scanline. The method including beginning in the scan-out process scanning the video frame and the one or more user interface features to the one or more input frame buffers at a corresponding flip-time for the video frame.