Research And Implementation Of Multi USB Camera System Based WINCE 6.0 Platform

With the wide application of USB Camera,USB Camera has become one of the standard configurations of forklift truck computers.At present,most forklift truck computers are equipped with Win CE 6.0 embedded real-time operating system,but the system does not have a USB Camera driver-free program.Users need to install the corresponding driver before using the USB Camera device.When replacing different types of USB cameras,A new driver needs to be reinstalled.At the same time,the traditional USB Camera driver can only support a single USB Camera device,and multiple USB Camera devices cannot work concurrently,which brings great inconvenience to the user.In view of the above problems,this paper mainly studies the application of UVC protocol proposed by USB-IF organization on forklift truck on-board computer,and combines the shortcomings of the company's forklift truck terminal to study the Multi USB Camera drive system.The system mainly includes five.Function module: UVC standard protocol implementation module,UVC driver hardware association layer module,UVC stream driver module,audio and video conversion module and multiple USB camera concurrent working modules.Specifically,the main work of the thesis is as follows:1.Design and implement the UVC standard protocol implementation module.By supporting the UVC1.1 standard protocol,the interaction between Descriptor and Requests on the USB bus is implemented,and on this basis,all USB Camera devices based on UVC1.1 standard protocols are compatible.Compared with the traditional USB Camera,plug and play is really implemented.2.Design and implement UVC driver hardware correlation module.This module abstracts all the hardware parameters related to Camera device,hides the implementation details of hardware parameters,and provides standard API access interface.3.The UVC flow driver module is designed and implemented.The standard Win CE driver interface is provided for the video application module to be invoked through standard API.It includes two stream interfaces,CAM_XXX and PIN_XXX,which interact with 3 devices and Camera devices in software: Adapter,Pin and Stream.Adapter is the abstraction of the Camera specific device,corresponding to the flow interface of CAM_XXX,and Pin is the device used by DShow to capture video data,and Stream represents the data flowing through.4.The audio and video conversion module is designed and implemented.The video format conversion mode based on Directshow framework is provided.The module uses the mainstream Filter design pattern to realize real-time conversion,audio and video separation and rendering between MJPEG->H.264,MJPEG-> RGB and many different video formats.5.Designed and implemented multiple USB camera concurrent working modules.The virtual device object is used to map the corresponding USB camera hardware,and the virtual device object is manipulated to realize the concurrent management of multiple USB cameras.When the USB camera device is added,and removed,the module synchronizes the data stream by creating a delete virtual device object.