IPTV論文：IPTV視頻質(zhì)量監(jiān)控系統(tǒng)的研究與設(shè)計

1、IPTV論文：IPTV視頻質(zhì)量監(jiān)控系統(tǒng)的研究與設(shè)計【中文摘要】IP 網(wǎng)絡(luò)作為 IPTV 業(yè)務(wù)的電信運(yùn)營網(wǎng)絡(luò)載體，存在 著一些固有缺陷：服務(wù)質(zhì)量 QoS 得不到很好保證、有效管理手段少，隨著不斷增加的網(wǎng)絡(luò)用戶和應(yīng)用，網(wǎng)絡(luò)負(fù)擔(dān)沉重、網(wǎng)絡(luò)性能下降，影響 了用戶體驗(yàn)效果。保障良好的用戶體驗(yàn)質(zhì)量QoE 是 IPTV 業(yè)務(wù)成功發(fā)展和推廣的關(guān)鍵所在，因此 IPTV 的視頻質(zhì)量監(jiān)控成為一個研究熱點(diǎn)。本文對基于 IPv6 網(wǎng)絡(luò)下的 IPTV 直播系統(tǒng)中的視頻質(zhì)量監(jiān)控課題進(jìn)行 研究和設(shè)計。所設(shè)計的原型系統(tǒng)框架由視頻采集端、復(fù)合傳輸子系統(tǒng)、 IPv6網(wǎng)絡(luò)、接收端和視頻質(zhì)量監(jiān)控五部分組成。媒體服務(wù)器端將多 路節(jié)目視頻

2、采集、復(fù)合成一路 TS 流對目標(biāo)組播地址發(fā)出，在 RTP 會話 中多路復(fù)合傳輸；接收客戶端通過流分解及流標(biāo)簽選擇解碼播放觀看 節(jié)目流；播放過程中接收端中的視頻質(zhì)量監(jiān)控 Age nt 定期發(fā)送 RTC 阪 饋控制信包，質(zhì)量監(jiān)控服務(wù)器端接收和分析反饋信息并向媒體服務(wù)器 反饋,媒體服務(wù)器根據(jù)相應(yīng)策略進(jìn)行自適應(yīng)調(diào)整、輸出與反饋狀況相 適應(yīng)的碼流。視頻傳輸對帶寬、丟包率、時延和時延抖動都有很高的 要求,但 IP 網(wǎng)絡(luò)可用帶寬動態(tài)變化，數(shù)據(jù)分組丟失、時延和抖動無法 預(yù)見,本文引入流媒體端到端傳輸控制技術(shù)努力提高系統(tǒng)的QoS 針對傳統(tǒng)的實(shí)時流傳輸控制算法AIMD的不足一一不能平滑發(fā)送端發(fā)送 速率,本文設(shè)計了

3、改進(jìn)的直播實(shí)時流傳輸控制算法LBR-AIMD 該算法在各客戶端加入 Age nt 定期反饋控制信息，引入指數(shù)加權(quán)移動平均值 平滑丟包率，把計算獲得的丟包率與兩個丟包率閾值比較，將網(wǎng)絡(luò)狀態(tài)分類為空閑、適中和擁塞，并根據(jù)分處各狀態(tài)的接收端數(shù)目比例判 斷整體網(wǎng)絡(luò)狀況，媒體服務(wù)器端據(jù)此通過對節(jié)目碼流調(diào)節(jié)使會話丟包 率保持在正常丟包率的范圍之內(nèi)，接收帶寬、時延和抖動性能得到改 善。同時根據(jù)網(wǎng)絡(luò)狀態(tài)變化對傳輸控制周期也進(jìn)行了調(diào)節(jié)。通過對原型系統(tǒng)的測試，直播系統(tǒng)客戶端視頻畫面穩(wěn)定、播放流暢，具有較好的 用戶體驗(yàn)效果。對傳輸控制算法 LBR-AIMD 勺測試表明，接收端“服務(wù) 質(zhì)量調(diào)節(jié)振蕩”現(xiàn)象幾率減少，比傳

4、統(tǒng)實(shí)時流式傳輸 AIMD 調(diào)節(jié)控制算 法的性能有一定改進(jìn)。論文最后對大型直播系統(tǒng)提高媒體服務(wù)器端對 接收端反饋信息響應(yīng)速度的 RTCP 分級反饋控制框架進(jìn)行了討論，并 對全文進(jìn)行了總結(jié)和系統(tǒng)開發(fā)的進(jìn)一步展望?！居⑽恼?As the carrier of IPTV telecom operat ingn etwork, IP n etwork has some in here nt defects: no guara nteesfor good service quality, less effectivemanagementmeans. Withthe ever- in creas ing

5、 users and applicatio ns, the n etworkburdens would becomeheavier, its performanee will decline and userexperiences will be degraded. Ensuring good userexperie nces is one of the key issues to the rapid developme nt andpromotion of IPTV, so the video quality monitoring for IPTV becomes aresearch hot

6、spot.This thesis studies and desig ns a video qualitymonitoring system for IPTV under the IPv6 en vir onment. The desig nedprototype framework con sists of video acquisiti on module, multiplex ingmodule, IPv6 n etwork, receiver module and video mon itori ng subsystem.The media server multiplexes sev

7、eral captured video programs into onetransport stream and forwards it targeting a multicast address at aRTPsession. The receiver clients receive the stream, then de-multiplex,select, decode and play the wan ted program.Mea nwhile, the Age nt at the clie nts sends out RTCP feedback packetsperiodicall

8、y, and the video quality-monitoringserverreceives them, analyzes the received feedback information,andthen sends the analysis results to the media server. According to thecorresp onding strategy, the media server adjusts video program qualityproperly for the feedback.Video flow has requireme nts on

9、high bandwidth, less packet loss ratio, less time delay and jitter, but the packetloss ratio, time delay and jitter cannot be foreseen in IP network whosebandwidth is variable time to time. This thesis introduces a mechanism forstreami ng media en d-to-e nd tran smissi on con trol to try to improve theQoS in video tran smissi on. To improve the performa nee of AIMD, thetraditi onal tran smissi on con trol algorithm for real-time flow, that cannotsmooth sending rate on sender side, this thesis pro