Server Display Buffer Scan-Out for Low-Latency Cloud Gaming
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Solution Overview
Problem
Cloud gaming systems face high latency and instability due to complex frame generation, encoding, variable network communication, and clock drift between servers and clients, affecting the smoothness of video display.
Innovation Solution
Perform high-speed or early scan-out operations of server display buffers, synchronizing VSYNC signals, and adjusting timing offsets to reduce one-way latency by initiating the encode process earlier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional scan-out operations are performed at VSYNC timing, then display synchronization is maintained, but one-way latency increases and video smoothness deteriorates
Solution Approach 1:
The patent performs scan-out operations at flip-time, which is before the VSYNC signal occurs. This preliminary action allows the encoding process to start earlier, reducing one-way latency from server to client without compromising display synchronization, as the scan-out is prepared in advance of the actual display refresh cycle
2Speed
If high-speed scan-out is performed, then one-way latency is reduced, but system complexity increases due to timing synchronization requirements
Solution Approach 1:
The patent dynamically adjusts the scan-out timing based on the flip-time of the frame buffer. Instead of using fixed VSYNC timing, the system adapts the scan-out operation to occur at the optimal moment (flip-time) determined by the rendering pipeline, allowing high-speed operation while maintaining synchronization through flexible timing control
3Loss of time
If early scan-out at flip-time is performed, then encoding starts earlier reducing latency, but timing precision requirements increase
Solution Approach 1:
The system uses feedback from the flip-time signal to trigger the scan-out operation. The flip-time event provides a precise, hardware-generated timing reference that automatically synchronizes the scan-out with the frame buffer state, eliminating the need for complex software timing calculations and ensuring high precision without increasing system complexity
Data Source
AI summary
A method for cloud gaming. The method including generating a video frame when executing a video game at a server, wherein the video frame is stored in a frame buffer. The method including determining a maximum pixel clock for a chip-set including a scan-out block. The method including determining a frame rate setting based on the maximum pixel clock and an image size of a target display of a client. The method including determining a speed setting value for the chip-set. The method including scanning the video frame into the scan-out block from the frame buffer. The method including scanning-out the video frame from the scan-out block to the encoder at the speed setting value.