遠端監控系統在目前日常生活中扮演著重要的角色，一般的遠端監控系統主要利用IP攝影機將擷取的影像透過網路傳送到監控端的電腦，在利用電腦螢幕顯示。這樣的架構仍存在著以下兩個缺點：

(1) 可移動性不高：
一般人不可能隨身出門都帶著電腦，所以往往只有在家裡或者辦公室等有電腦設備的地方才能進行監控的行為，這使得遠端監控系統無法發揮最好的效果。
(2) IP位置經常變動：
IP攝影機通常利用DHCP取得IP位址，但是DHCP經過一段時間後，就必須重新取抓取新的IP位址，導致IP攝影機的IP位址不斷地變動。對於網路設定不熟悉的使用者而言，這將造成監控上的困難。

本論文針對以上兩項缺點進行改善。本論文的目的就是希望能夠在PDA的平台上實現IP攝影機的Viewer，透過PDA平台來提高遠端監控系統的可移動性。此外，我們也希望整合SIP的功能，讓原本的IP攝影機變成本論文中所謂的SIP-Cam，進而以SIP帳號取代IP位址，以避免IP位址更改後造成的影響。

本論文的研究方法，首先我們使用Kaise PXA270開發板作為本論文的PDA，ImagiaTek公司的MPG440 RDK套件作為IP攝影機。接著，我們使用開放原始碼程式進行修改、重新編譯，以達到本論文的架構與需求。

本論文尚提出一種FrameDrop的機制，在SIP-Cam端採取四種不同程度的封包丟棄措施，在PDA端也會依據緩衝區使用情況而在解碼時進行封包丟棄的動作，以減輕PDA解碼影像上的負擔，使得監控更穩定。

The remote surveillance system plays an important role in the daily life. Generally, the remote surveillance system works by transmitting the images captured by the IP camera over the network to the surveillant’s computer. The architecture described above still exists two drawbacks as follows. The first is low mobility, and the second is that IP address of the IP camera changes frequently.

(1) Low mobility :
No one will bring the cumbersome computer whenever he (or she) goes out. In other words, we could only make use of the remote surveillance system when we are in the office or stay in home. It means we can’t take better advantage of the remote surveillance system.
(2) IP address changes frequently :
IP camera always gets its IP address by DHCP server. There exists a lease time in DHCP service. When the lease time expires, DHCP server has to renew the IP address of the IP camera. That will make the IP address of IP camera change frequently. For the person who is unfamiliar with the network setting, it’s difficult to make use of the IP camera.

The paper improves two drawbacks described above. To Implement a viewer of IP camera for PDA platform and enhance the mobility of remote surveillance system are our objective. In addition, so called SIP-Cam in this paper integrates SIP into IP camera. In order to prevent the trouble about that IP address changes frequently, SIP-Cam replaces IP address with SIP account.

First, we use KS_PXA270 board as the PDA proposed in the paper, MPG440 RDK kit of ImagiaTek as SIP-Cam. Then, we achieve our objective of this paper by modifying and rebuilding the open source projects.

We also propose a mechanism to drop frames, called DropFrame. The DropFrame mechanism has four kinds of policies to alleviate the loading of the PDA.

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