【摘要】：近年來,隨著國民經(jīng)濟的不斷發(fā)展,視頻監(jiān)控技術(shù)已經(jīng)在政府、教育、娛樂、醫(yī)療、公共交通等眾多領(lǐng)域得到了廣泛的應(yīng)用。傳統(tǒng)的視頻監(jiān)控系統(tǒng)主要基于有線網(wǎng)絡(luò)進行監(jiān)控,具有系統(tǒng)布線復(fù)雜、鋪設(shè)成本較高以及靈活性較差等缺點,無法滿足人們隨時隨地進行監(jiān)控的需求。隨著無線網(wǎng)絡(luò)技術(shù)的不斷發(fā)展、智能手機硬件水平的不斷提高,移動視頻監(jiān)控系統(tǒng)得以實現(xiàn),并在實際應(yīng)用中顯示出極大的競爭優(yōu)勢。本文基于Android平臺,對移動視頻監(jiān)控系統(tǒng)的實現(xiàn)過程進行研究。本文針對移動視頻監(jiān)控系統(tǒng)的視頻編碼、傳輸、組包、解碼以及視頻播放等環(huán)節(jié)進行了詳細的介紹。首先,移動視頻監(jiān)控系統(tǒng)有別于傳統(tǒng)的視頻監(jiān)控系統(tǒng),需要通過無線網(wǎng)絡(luò)進行數(shù)據(jù)傳輸。由于無線網(wǎng)絡(luò)帶寬有限且穩(wěn)定性較差,’因此本系統(tǒng)采用圖像壓縮比率較高、網(wǎng)絡(luò)適應(yīng)性強的H.264編碼標準進行編碼。其次,在數(shù)據(jù)傳輸方面?zhèn)鹘y(tǒng)的方式是采用RTP協(xié)議與RTCP協(xié)議配合進行數(shù)據(jù)傳輸。由于這種傳輸方式實現(xiàn)較為復(fù)雜,因此本文采用一種自定義的通用消息頭結(jié)構(gòu)對視頻數(shù)據(jù)進行傳輸,以降低數(shù)據(jù)傳輸?shù)膹?fù)雜度。然后,本系統(tǒng)為了提高視頻監(jiān)控的時效性,采用UDP協(xié)議作為系統(tǒng)傳輸層協(xié)議。由于UDP協(xié)議是不可靠傳輸協(xié)議,因此在數(shù)據(jù)傳輸過程中不可避免地會出現(xiàn)丟包的現(xiàn)象。系統(tǒng)對丟包現(xiàn)象進行了精細的處理,避免出現(xiàn)由于數(shù)據(jù)丟包造成的播放畫面的花屏或卡頓的現(xiàn)象。再次,對于視頻數(shù)據(jù)的解碼過程,Android系統(tǒng)自帶的多媒體處理控件OpenCore有被Stagefright取代的趨勢,而Stagefright控件又有支持的文件格式較少且不穩(wěn)定的缺點。與Android系統(tǒng)自帶的多媒體處理引擎相比,FFmpeg具有跨平臺、框架穩(wěn)定、支持文件格式較多等優(yōu)點,因此本系統(tǒng)采用FFmpeg對視頻數(shù)據(jù)進行解碼。本文對于FFmpeg的編譯過程也進行了詳細的講解。最后,對于視頻數(shù)據(jù)的播放,本系統(tǒng)分為歷史視頻數(shù)據(jù)和實時視頻數(shù)據(jù)兩種情況進行處理。系統(tǒng)將耗時的邏輯操作放入子線程中進行,避免了由于頻繁地更新UI線程造成線程阻塞現(xiàn)象的發(fā)生。通過實踐證明,本文提出的基于Android平臺的移動視頻監(jiān)控系統(tǒng),能夠滿足實際項目需求,具有較好的監(jiān)控效果。
[Abstract]:In recent years, with the development of national economy, video surveillance technology has been widely used in many fields such as government, education, entertainment, medical treatment, public transportation and so on. The traditional video surveillance system is mainly based on wired network, which has the disadvantages of complex system wiring, high laying cost and poor flexibility, which can not meet the needs of people to monitor at any time and anywhere. With the development of wireless network technology and the improvement of smart phone hardware, the mobile video surveillance system has been realized, and has shown a great competitive advantage in practical applications. Based on Android platform, the realization process of mobile video surveillance system is studied in this paper. In this paper, video coding, transmission, packet formation, decoding and video playing of mobile video surveillance system are introduced in detail. Firstly, the mobile video surveillance system is different from the traditional video surveillance system, and it needs to transmit data through wireless network. Because the bandwidth of wireless network is limited and the stability is poor, this system adopts the H.264 coding standard which has high image compression ratio and strong network adaptability. Secondly, the traditional way of data transmission is to use RTP protocol and RTCP protocol for data transmission. Due to the complexity of this transmission mode, a custom universal header structure is used to transmit video data in order to reduce the complexity of data transmission. Then, in order to improve the timeliness of video surveillance, UDP protocol is adopted as the system transport layer protocol. Because UDP is an unreliable transport protocol, packet loss will inevitably occur in the process of data transmission. The system handles the phenomenon of packet loss carefully to avoid the phenomenon of display screen or Catton caused by data packet loss. Thirdly, for the decoding process of video data, the multimedia processing control OpenCore of Android system has the tendency to be replaced by Stagefright, while the Stagefright control has the disadvantage of less and unstable file format. Compared with the multimedia processing engine of Android system, FFmpeg has the advantages of cross-platform, stable frame and more supporting file formats. Therefore, the system uses FFmpeg to decode video data. The compilation process of FFmpeg is also explained in detail in this article. Finally, the system is divided into historical video data and real-time video data. The system puts the time-consuming logic operation into the child thread to avoid the thread blocking caused by the frequent updating of the UI thread. It is proved by practice that the mobile video surveillance system based on Android platform can meet the needs of the actual project and has a good monitoring effect.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN948.6

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本文編號：2328627