針對影像監控系統的跨平台彈性架構設計

Abstract

隨著價格便宜的 IP camera 的普及，現在一般家庭或公車亦可利用 IP camera 來監控而對自身及乘客安全加以防護，也使得影像監控系統的開發重點演進到第四階段，純粹以 IP Camera 當作影像資訊來源的 Standalone 裝置。現在市面上各家 IP camera 廠商皆有提供影像監控系統，但只能適用於自己的產品且大多架構在 Windows 平台上，而我們的系統需求為可以使用不同廠牌之 IP-camera，且可應用於嵌入式系統上，來增加客戶使用上的方便性。 為了建構一個跨平台的影像監控系統，並增加對嵌入式系統的支援，達到容易移植、容易彈性的擴充與動態的操作三項目標。對於系統完整執行程序的設計，我們參考目前相當熱門的 Windows DirectShow 架構，其系統設計是為了簡化複雜的多媒體程式開發而發展的一套龐大系統框架，DirectShow將主要系統動作區分為來源、轉換、呈現三個 Filter 來處理，再以 Filter Graph 來完成完整的多媒體流程。 在整體的系統設計方面，我們參考用於交互介面系統設計的 MVC (Model-View-Controller) 設計模式，加以調整來進行系統開發的架構設計，此調整的模式可以具體表示出中小型系統開發時的系統設計模式，且在使用上有很大的靈活性，使系統各個部分在開發時皆可獨立進行，且可彈性的增加支援的裝置與格式，如：來源部分可以掛載不同廠牌之 IP-camera；轉換部分則可以增加各種影像處理的 tools 等，最後再依照不同的功能進行系統整合即可。 我們對即時的影像監視系統提供了彈性的架構，使系統對影像擷取、轉換、播放、儲存、多重傳送等單元皆能獨立運作，達到影像監控、影像儲存、影像串流及影像多重傳送等功能。並移植到嵌入式平台上，完成開發 IP Camera Standalone 的目標。

Since IP camera is prevalent in recent years, now a surveillance system could be used in every family or on bus to secure personal or passengers’ safety. And for facilitation, the development of surveillance system launch into the IP Camera Standalone device. A surveillance system is involved complex multimedia application. The DirectShow API and the GStreamer API is designed to simplify the development of multimedia application on Windows and Linux platform, respectively. DirectShow divides a complex multimedia task into a sequence of fundamental processing steps known as filters. There are three main types of filters: Source, Transform, and Rendering. Our system acquires the design of DirectShow to divide our main task processes. In respect to the entire system design, pattern design is a design method that picking up commonness in huge and complex design fields, setting up a reusable and creatable, optimizing quality, reducing cost, having the advantages of share, simplicity and credibility. So we referred to the Model-View-Controller (MVC) design pattern and modified it to be suitable for our system development. This paper proposes a cross-platform flexible architecture for surveillance video system, including operations of capturing, decoding, encoding, and rendering. It is taken into data control and some functional modules apart. And it is flexibility in combining or increasing data and modules to perform the functionalities of monitoring, recording, streaming out and multicast. And we ported the surveillance video system to an embedded device to get the aim of development of IP Camera Standalone.