USB Camera Throughput Control via Dynamic Pixel Clock Adjustment
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Solution Overview
Problem
USB cameras using BULK endpoints face performance challenges in video streaming due to potential throughput limitations and frame drops, especially when the host unit's capabilities are exceeded or USB bus utilization increases.
Innovation Solution
An optimizing system that regulates video streaming by utilizing a circular buffer memory device and deploying strategies such as varying the CMOS pixel clock, manipulating blanking times, and selectively dropping packets to manage data throughput and prevent congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If BULK transfers are used to achieve high bandwidth throughput, then data transfer rate is improved, but frame drops and reliability deteriorate when host throughput capabilities are exceeded
Solution Approach 1:
The patent implements dynamic adjustment of the camera's data transfer rate based on real-time monitoring of host unit throughput capabilities. The system continuously adapts the streaming rate to match available host processing capacity, preventing overload and frame drops while maximizing bandwidth utilization when capacity is available.
Solution Approach 2:
The system employs a feedback mechanism where the host unit monitors its own throughput capabilities and communicates this information back to the USB camera. The camera then adjusts its data generation rate accordingly, creating a closed-loop control system that maintains reliable operation at optimal speeds.
2Reliability
If ISOCH transfers are used to guarantee bandwidth allocation, then reliability is improved, but flexibility and maximum bandwidth utilization deteriorate
Solution Approach 1:
The patent changes the fundamental parameter of bandwidth allocation from fixed (ISOCH) to variable (BULK with dynamic control). By using BULK transfers with dynamically adjusted data rates based on host capacity, the system achieves both reliability and flexibility, allowing bandwidth to adapt to changing system conditions while maintaining stable operation.
Data Source
AI summary
A system and method to optimize video streaming of a plurality of USB cameras streaming via a bulk interface of a universal serial bus (USB), the system comprising a host unit communicating on universal serial bus (USB) via the bulk interface, a throughput analyzer computer program residing in the host unit, at least a USB Camera with a varying throughput, a dynamically programmable image sensor varies a throughput of the USB camera, a throughput control block of the USB camera receives input from the throughput analyzer computer program and adjusts the throughput of the camera, the USB controller regulates a transmission of USB packet buffers from each of the USB Camera to the host unit. The method comprises assessing by the throughput analyzer computer program of the universal serial bus utilization by the host unit by including all connected devices, and includes selectively dropping a plurality of data packet/frames.