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<div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62bb3b46405aad31f7132f9f/bg1.jpg"><div class="c x0 y1 w2 h0"><div class="t m0 x1 h2 y2 ff1 fs0 fc0 sc0 ls0 ws0"> </div><div class="t m0 x1 h3 y3 ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 y4 ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 y5 ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 y6 ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 y7 ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 y8 ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 y9 ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x2 h4 ya ff2 fs2 fc0 sc1 ls0 ws0">“深圳杯<span class="_ _0"></span>”数学建<span class="_ _0"></span>模挑战赛<span class="_ _1"> </span><span class="ff3">A<span class="_ _1"> </span></span>题<span class="ff3"> </span></div><div class="t m0 x3 h5 yb ff2 fs3 fc0 sc1 ls0 ws0">网络侧<span class="_ _0"></span>估计终<span class="_ _0"></span>端视频体<span class="_ _0"></span>验建<span class="_ _0"></span>模<span class="ff3"> </span></div><div class="t m0 x1 h6 yc ff1 fs3 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 yd ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x1 h3 ye ff1 fs1 fc0 sc1 ls0 ws0"> </div><div class="t m0 x4 h7 yf ff2 fs1 fc0 sc1 ls0 ws0">参赛队员：郭海龙<span class="_ _0"></span><span class="ff3"> </span>杨继犇<span class="ff3"> </span>姚强<span class="ff3"> </span></div><div class="t m0 x5 h7 y10 ff2 fs1 fc0 sc1 ls0 ws0">指导教师：闫厉<span class="ff3"> </span></div><div class="t m0 x6 h7 y11 ff2 fs1 fc0 sc1 ls0 ws0">学校：长春工业大学<span class="ff3"> </span></div><div class="t m0 x7 h7 y12 ff3 fs1 fc0 sc0 ls0 ws0"> </div><div class="t m0 x7 h7 y13 ff3 fs1 fc0 sc0 ls0 ws0"> </div></div></div><div class="pi" data-data='{"ctm":[1.611792,0.000000,0.000000,1.611792,0.000000,0.000000]}'></div></div>
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<div id="pf2" class="pf w0 h0" data-page-no="2"><div class="pc pc2 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62bb3b46405aad31f7132f9f/bg2.jpg"><div class="c x0 y1 w2 h0"><div class="t m0 x8 h2 y2 ff1 fs0 fc0 sc0 ls0 ws0">I </div><div class="t m0 x9 h3 y14 ff4 fs1 fc0 sc1 ls0 ws0">摘要<span class="ff1"> </span></div><div class="t m0 xa h8 y15 ff4 fs4 fc0 sc0 ls0 ws0">在终端视频体验过程中，<span class="_ _2"></span>影响用户体验的两个关键指标为初始缓冲等待时间</div><div class="t m0 x7 h8 y16 ff4 fs4 fc0 sc0 ls0 ws0">和在视频播放过程中的卡顿缓冲时间，<span class="_ _2"></span>但这两个指标与网络侧变量之间的关系并</div><div class="t m0 x7 h8 y17 ff4 fs4 fc0 sc0 ls0 ws0">不明确，<span class="_ _3"></span>为了明确这两个关键指标与网络侧变量之间的关系，<span class="_ _3"></span>本文结合移动视频</div><div class="t m0 x7 h8 y18 ff4 fs4 fc0 sc0 ls0 ws0">传输协议等相关知识，<span class="_ _3"></span>通过对实验数据进行分析和挖掘，<span class="_ _3"></span>建立了<span class="sc1">初始缓冲时延映</span></div><div class="t m0 x7 h8 y19 ff4 fs4 fc0 sc1 ls0 ws0">射模型<span class="sc0">与</span>卡顿时<span class="_ _0"></span>长占比函数模<span class="_ _0"></span>型<span class="sc0">。<span class="ff1"> </span></span></div><div class="t m0 xa h8 y1a ff4 fs4 fc0 sc0 ls0 ws0">针对<span class="sc1">初始缓冲时延<span class="_ _0"></span>映射模型<span class="_ _0"></span></span>，<span class="_ _4"></span>通过实验数据拟合、<span class="_ _4"></span>皮尔森相关性检验等分析</div><div class="t m0 x7 h8 y1b ff4 fs4 fc0 sc0 ls0 ws0">方法进行探究，<span class="_ _3"></span>明确了初始缓冲时延与初始缓冲峰值速率呈负相关、<span class="_ _3"></span>与端到端环</div><div class="t m0 x7 h8 y1c ff4 fs4 fc0 sc0 ls0 ws0">回时间（<span class="ff1">E2E <span class="_ _5"></span>RTT</span>）呈正相关，进而建立初始缓冲时延与网络侧变量之间的初始</div><div class="t m0 x7 h8 y1d ff4 fs4 fc0 sc0 ls0 ws0">函数关系，<span class="_ _6"></span>然后对初始缓冲加载阶段以及实验数据进一步分析，<span class="_ _6"></span>据此，<span class="_ _6"></span>基于初始</div><div class="t m0 x7 h8 y1e ff4 fs4 fc0 sc0 ls0 ws0">函数关系初步建立初始缓冲时延映射模型；之后通过<span class="_ _7"> </span><span class="ff1">MATLAB<span class="_ _7"> </span></span>对实验数据及模型</div><div class="t m0 x7 h8 y1f ff4 fs4 fc0 sc0 ls0 ws0">进行图像拟合、残差分<span class="_ _0"></span>析，进而大体完善模型<span class="_ _0"></span>；并分别对模型进行修<span class="_ _0"></span>正和优化，</div><div class="t m0 x7 h8 y20 ff4 fs4 fc0 sc0 ls0 ws0">完成<span class="sc1">初始缓冲时延<span class="_ _0"></span>映射模型<span class="_ _0"></span></span>的建立；最后对该模型的优缺点进行了探讨。<span class="ff1"> </span></div><div class="t m0 xa h8 y21 ff4 fs4 fc0 sc0 ls0 ws0">针对<span class="sc1">卡顿时长占比<span class="_ _0"></span>函数模型<span class="_ _0"></span></span>，<span class="_ _4"></span>首先对实验数据进行分析及筛选，<span class="_ _4"></span>并结合相关</div><div class="t m0 x7 h8 y22 ff4 fs4 fc0 sc0 ls0 ws0">理论，<span class="_ _3"></span>确定卡顿时长占比在网络侧的主要影响指标为播放阶段平均下载速率，<span class="_ _3"></span>综</div><div class="t m0 x7 h8 y23 ff4 fs4 fc0 sc0 ls0 ws0">合考虑后从两个角度出发分别建立各自对应的<span class="sc1">卡顿时<span class="_ _0"></span>长占比函数模型</span>，<span class="_ _8"></span>并对模型</div><div class="t m0 x7 h8 y24 ff4 fs4 fc0 sc0 ls0 ws0">进行优选；<span class="_ _3"></span>之后随机抽取多组实验数据对模型进行回归分析，<span class="_ _3"></span>用以检验模型的可</div><div class="t m0 x7 h8 y25 ff4 fs4 fc0 sc0 ls0 ws0">靠度、<span class="_ _9"></span>验证模型的正确性；<span class="_ _9"></span>而后，<span class="_ _9"></span>对模型进行了优缺点分析及评价，<span class="_ _9"></span>提出对应改</div><div class="t m0 x7 h8 y26 ff4 fs4 fc0 sc0 ls0 ws0">进办法。<span class="ff1"> </span></div><div class="t m0 xa h8 y27 ff4 fs4 fc0 sc0 ls1 ws0">为了对模型的<span class="sc1 ls0">可<span class="_ _a"> </span>用<span class="_ _5"> </span>性<span class="_ _b"> </span></span>进行论证，一方面基于视频体验评分测试软件</div><div class="t m0 x7 h8 y28 ff1 fs4 fc0 sc1 ls0 ws0">Speedv<span class="_ _0"></span>ideo<span class="_ _c"> </span><span class="ff4 sc0">及其网络运营平台，对所在地多个区域进行综<span class="_ _0"></span>合测试并提取相关数</span></div><div class="t m0 x7 h8 y29 ff4 fs4 fc0 sc0 ls0 ws0">据；<span class="_ _3"></span>另一方面通过随机抽样的方法对所给实验数据进行提取。<span class="_ _3"></span>将两方面所测结果</div><div class="t m0 x7 h8 y2a ff4 fs4 fc0 sc0 ls0 ws0">分别与理论模型计算所得结果进行比较，<span class="_ _6"></span>以此验证模型的可用性。<span class="_ _6"></span>最后，<span class="_ _6"></span>基于建</div><div class="t m0 x7 h8 y2b ff4 fs4 fc0 sc0 ls0 ws0">立的初始缓冲时延映射<span class="_ _0"></span>模型以及卡顿时长占比<span class="_ _0"></span>函数模型，从网络侧的<span class="_ _0"></span>角度出发，</div><div class="t m0 x7 h8 y2c ff4 fs4 fc0 sc0 ls0 ws0">提出合理化的建议用以改善网络架构，提高用户终端视频体验质量。<span class="ff1"> </span></div><div class="t m0 xa h8 y2d ff4 fs4 fc0 sc1 ls0 ws0">关键词<span class="sc0">：初始缓冲时延映射模型<span class="ff1"> </span>卡顿时长占比函数模型<span class="ff1"> Speedvideo</span></span></div></div></div><div class="pi" data-data='{"ctm":[1.611792,0.000000,0.000000,1.611792,0.000000,0.000000]}'></div></div>
<div id="pf3" class="pf w0 h0" data-page-no="3"><div class="pc pc3 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62bb3b46405aad31f7132f9f/bg3.jpg"><div class="c x0 y1 w2 h0"><div class="t m0 x8 h2 y2 ff1 fs0 fc0 sc0 ls0 ws0">1 </div><div class="t m0 x9 h3 y14 ff4 fs1 fc0 sc1 ls0 ws0">目录<span class="ff1"> </span></div><div class="t m0 x7 h8 y2e ff4 fs4 fc0 sc0 ls0 ws0">摘要<span class="ff1">................................................................ <span class="_ _8"></span>I<span class="ff5 fs5"> </span></span></div><div class="t m0 x7 h8 y2f ff4 fs4 fc0 sc0 ls0 ws0">一、问题重述<span class="ff1">........................................................ <span class="_ _8"></span>1<span class="ff5 fs5"> </span></span></div><div class="t m0 xa h8 y30 ff1 fs4 fc0 sc0 ls0 ws0">1.1 <span class="ff4">背景知识</span>.................................................... <span class="_ _8"></span>1<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y31 ff1 fs4 fc0 sc0 ls0 ws0">1.2 <span class="ff4">问题提出</span>.................................................... <span class="_ _8"></span>1<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y32 ff1 fs4 fc0 sc0 ls0 ws0">1.3 <span class="ff4">要解决的问题</span>................................................ <span class="_ _8"></span>2<span class="ff5 fs5"> </span></div><div class="t m0 x7 h8 y33 ff4 fs4 fc0 sc0 ls0 ws0">二、问题分析<span class="ff1">........................................................ <span class="_ _8"></span>2<span class="ff5 fs5"> </span></span></div><div class="t m0 x7 h8 y34 ff4 fs4 fc0 sc0 ls0 ws0">三、模型假设<span class="ff1">........................................................ <span class="_ _8"></span>3<span class="ff5 fs5"> </span></span></div><div class="t m0 x7 h8 y35 ff4 fs4 fc0 sc0 ls0 ws0">四、符号说明<span class="ff1">........................................................ <span class="_ _8"></span>4<span class="ff5 fs5"> </span></span></div><div class="t m0 x7 h8 y36 ff4 fs4 fc0 sc0 ls0 ws0">五、初始缓冲时延映射模型建立与评价<span class="ff1">.................................. <span class="_ _8"></span>5<span class="ff5 fs5"> </span></span></div><div class="t m0 xa h8 y37 ff1 fs4 fc0 sc0 ls0 ws0">5.1<span class="_ _d"> </span><span class="ff4">初始缓冲时延映射模型的建立</span> <span class="_ _e"></span>.................................. <span class="_ _8"></span>5<span class="ff5 fs5"> </span></div><div class="t m0 xb h8 y38 ff1 fs4 fc0 sc0 ls0 ws0">5.1.1 <span class="ff4">初始缓冲时延在网络侧变量的影响因素分析</span>................ <span class="_ _8"></span>5<span class="ff5 fs5"> </span></div><div class="t m0 xb h8 y39 ff1 fs4 fc0 sc0 ls0 ws0">5.1.2 <span class="ff4">建立初始缓冲时延映射模型</span>............................. <span class="_ _8"></span>10<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y3a ff1 fs4 fc0 sc0 ls0 ws0">5.2 <span class="ff4">初始缓冲时延映射模型的分析与检验</span>........................... <span class="_ _8"></span>12<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y3b ff1 fs4 fc0 sc0 ls0 ws0">5.3 <span class="ff4">初始缓冲时延映射模型的分析与优化</span>........................... <span class="_ _8"></span>15<span class="ff5 fs5"> </span></div><div class="t m0 xb h8 y3c ff1 fs4 fc0 sc0 ls0 ws0">5.3.1 <span class="ff4">模型的分析</span>........................................... <span class="_ _8"></span>15<span class="ff5 fs5"> </span></div><div class="t m0 xb h8 y3d ff1 fs4 fc0 sc0 ls0 ws0">5.3.2 <span class="ff4">模型的优化</span>........................................... <span class="_ _8"></span>16<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y3e ff1 fs4 fc0 sc0 ls0 ws0">5.4 <span class="ff4">初始缓冲时延映射模型的总结与评价</span>........................... <span class="_ _8"></span>19<span class="ff5 fs5"> </span></div><div class="t m0 x7 h8 y3f ff4 fs4 fc0 sc0 ls0 ws0">六、卡顿时长占比函数模型建立与评价<span class="ff1">................................. <span class="_ _8"></span>21<span class="ff5 fs5"> </span></span></div><div class="t m0 xa h8 y40 ff1 fs4 fc0 sc0 ls0 ws0">6.1 <span class="ff4">卡顿时长占比与网络侧变量之间的函数模型建立</span>................. <span class="_ _8"></span>21<span class="ff5 fs5"> </span></div><div class="t m0 xb h8 y41 ff1 fs4 fc0 sc0 ls0 ws0">6.1.1 <span class="ff4">卡顿时长占比在网络侧变量中影响因素的探究</span>............. <span class="_ _8"></span>21<span class="ff5 fs5"> </span></div><div class="t m0 xb h8 y42 ff1 fs4 fc0 sc0 ls0 ws0">6.1.2<span class="_ _d"> </span><span class="ff4">卡顿时长占比函数模型的建立</span> <span class="_ _e"></span>........................... <span class="_ _8"></span>23<span class="ff5 fs5"> </span></div><div class="t m0 xb h8 y43 ff1 fs4 fc0 sc0 ls0 ws0">6.1.3<span class="_ _d"> </span><span class="ff4">卡顿时长占比函数模型的比较与选择</span> <span class="_ _e"></span>..................... <span class="_ _8"></span>25<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y44 ff1 fs4 fc0 sc0 ls0 ws0">6.2 <span class="ff4">卡顿时长占比函数模型的检验与误差分析</span>....................... <span class="_ _8"></span>27<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y45 ff1 fs4 fc0 sc0 ls0 ws0">6.3 <span class="ff4">卡顿时长占比函数模型的总结与评价</span>........................... <span class="_ _8"></span>28<span class="ff5 fs5"> </span></div><div class="t m0 x7 h8 y46 ff4 fs4 fc0 sc0 ls0 ws0">七、模型的综合评价及应用<span class="ff1">........................................... <span class="_ _8"></span>30<span class="ff5 fs5"> </span></span></div><div class="t m0 xa h8 y47 ff1 fs4 fc0 sc0 ls0 ws0">7.1 <span class="ff4">评价用户视频体验</span>........................................... <span class="_ _8"></span>30<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y48 ff1 fs4 fc0 sc0 ls0 ws0">7.2 <span class="ff4">模型的可用性论证</span>........................................... <span class="_ _8"></span>30<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y49 ff1 fs4 fc0 sc0 ls0 ws0">7.3 <span class="ff4">模型的应用</span>................................................. <span class="_ _8"></span>35<span class="ff5 fs5"> </span></div><div class="t m0 xa h8 y4a ff1 fs4 fc0 sc0 ls0 ws0">7.4 <span class="ff4">意见和建议</span>................................................. <span class="_ _8"></span>36<span class="ff5 fs5"> </span></div><div class="t m0 x7 h8 y4b ff4 fs4 fc0 sc0 ls0 ws0">八、拓展<span class="ff1">........................................................... <span class="_ _8"></span>37<span class="ff5 fs5"> </span></span></div><div class="t m0 x7 h8 y4c ff4 fs4 fc0 sc0 ls0 ws0">九、总结与展望<span class="ff1">..................................................... <span class="_ _8"></span>38<span class="ff5 fs5"> </span></span></div><div class="t m0 x7 h8 y4d ff4 fs4 fc0 sc0 ls0 ws0">参考文献<span class="ff1">........................................................... <span class="_ _8"></span>39<span class="ff5 fs5"> </span></span></div><div class="t m0 x7 h8 y4e ff4 fs4 fc0 sc0 ls0 ws0">附录<span class="ff1">............................................................... <span class="_ _8"></span>40<span class="ff5 fs5"> 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<div id="pf4" class="pf w0 h0" data-page-no="4"><div class="pc pc4 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62bb3b46405aad31f7132f9f/bg4.jpg"><div class="c x0 y1 w2 h0"><div class="t m0 x8 h2 y2 ff1 fs0 fc0 sc0 ls0 ws0">1 </div><div class="t m0 xc h3 y14 ff4 fs1 fc0 sc1 ls0 ws0">一、问题重述<span class="ff6 sc0"> </span></div><div class="t m0 x7 h8 y4f ff1 fs4 fc0 sc1 ls0 ws0">1.1 <span class="ff4">背景<span class="_ _0"></span>知识</span> </div><div class="t m0 xa h8 y50 ff4 fs4 fc0 sc0 ls0 ws0">基于<span class="ff1">TCP</span>的<span class="fc1">顺序流式传输</span>与播放技术，<span class="_ _2"></span>原理是当发送端<span class="ff1 fc1">TCP<span class="ff4">层接收应用层发送</span></span></div><div class="t m0 x7 h8 y51 ff4 fs4 fc1 sc0 ls0 ws0">的数据流时，<span class="ls2">这些</span>数据流会被<span class="fc0">发<span class="_ _0"></span>送端</span><span class="ff1">TCP</span>分区成适当长<span class="_ _0"></span>度的报文段，然后发送端</div><div class="t m0 x7 h8 y52 ff1 fs4 fc1 sc0 ls0 ws0">TCP<span class="ff4">把结果包传给</span>IP<span class="ff4">层，<span class="_ _3"></span><span class="ff1">IP<span class="ff4">层通过网络将包传送给接收端</span>TCP<span class="ff4">层，<span class="_ _3"></span>接收端会对已成</span></span></span></div><div class="t m0 x7 h8 y53 ff4 fs4 fc1 sc0 ls0 ws0">功收到的包发回一个确<span class="_ _0"></span>认（<span class="ff1">ACK</span>）<span class="_ _f"></span>；如果发送端在合理的<span class="_ _0"></span>往返时延（<span class="ff1 fc0">RT<span class="_ _0"></span>T</span>）内没有</div><div class="t m0 x7 h8 y54 ff4 fs4 fc1 sc0 ls0 ws0">收到确认，<span class="_ _6"></span>那么对应的数据包就会被认为已丢失并进行重传，<span class="_ _6"></span>同时，<span class="_ _6"></span>为了能够实</div><div class="t m0 x7 h8 y55 ff4 fs4 fc1 sc0 ls0 ws0">现更流畅的播放体验<span class="_ _0"></span>，顺序流式传输会<span class="_ _0"></span>在客户端设置缓冲区<span class="ff1">,<span class="_ _0"></span></span>通过对接收数据包</div><div class="t m0 x7 h8 y56 ff4 fs4 fc1 sc0 ls0 ws0">进行缓冲存储<span class="ff1">,</span>从而缓<span class="_ _0"></span>解网络动态变化导致的<span class="_ _0"></span>丢包、延时、抖<span class="_ _0"></span>动等异常状况对视</div><div class="t m0 x7 h8 y57 ff4 fs4 fc1 sc0 ls0 ws0">频流质量的影响</div><div class="t m0 xd h9 y58 ff1 fs6 fc1 sc0 ls0 ws0">[1]</div><div class="t m0 xe h8 y57 ff4 fs4 fc1 sc0 ls0 ws0">。<span class="ff1"> </span></div><div class="t m0 xa h8 y59 ff4 fs4 fc0 sc0 ls0 ws0">基于此，<span class="ff1">HTTP</span>自<span class="_ _0"></span>适应流技术应运而生<span class="_ _0"></span><span class="ff1">,</span>这种技术结合了<span class="ff1">HTT<span class="_ _0"></span>P</span>渐进式下<span class="_ _0"></span>载与传</div><div class="t m0 x7 h8 y5a ff4 fs4 fc0 sc0 ls0 ws0">统<span class="ff1">RTSP</span>流媒体的优点<span class="_ _0"></span>，<span class="fc1">原理是首先对原<span class="_ _0"></span>始视频进行压缩编码<span class="ff1">,<span class="_ _0"></span></span>获得多种编码比特</span></div><div class="t m0 x7 h8 y5b ff4 fs4 fc1 sc0 ls0 ws0">率版<span class="_ _0"></span>本<span class="_ _0"></span>的<span class="_ _0"></span>视频<span class="_ _0"></span>流文<span class="_ _0"></span>件<span class="_ _0"></span><span class="ff1">,</span>用<span class="_ _0"></span>来<span class="_ _0"></span>对<span class="_ _0"></span>应不<span class="_ _0"></span>同<span class="_ _0"></span>的视<span class="_ _0"></span>频质<span class="_ _0"></span>量<span class="_ _0"></span><span class="ff1">,<span class="_ _0"></span></span>在服<span class="_ _0"></span>务<span class="_ _0"></span>器端<span class="_ _0"></span>对<span class="_ _0"></span>视频<span class="_ _0"></span>流文<span class="_ _0"></span>件<span class="_ _0"></span>进行</div><div class="t m0 x7 h8 y5c ff4 fs4 fc1 sc0 ls0 ws0">切割<span class="ff1">,</span>分成时域长度相<span class="_ _0"></span>同的数据块<span class="ff1">,</span>同<span class="_ _0"></span>时确保每个数据块能够<span class="_ _0"></span>独立解码。这样<span class="_ _0"></span><span class="ff1">,</span>当</div><div class="t m0 x7 h8 y5d ff4 fs4 fc1 sc0 ls0 ws0">用户观看视频时<span class="ff1">,</span>移动<span class="_ _0"></span>智能终端发送网络请求<span class="_ _0"></span><span class="ff1">,</span><span class="fc0">渐进地向<span class="ff1">WE<span class="fc1">B</span></span></span>服<span class="_ _0"></span>务器下载分割后的</div><div class="t m0 x7 h8 y5e ff4 fs4 fc1 sc0 ls0 ws0">视频数据块<span class="ff1">,</span>并会按顺<span class="_ _0"></span>序解码播放视频<span class="_ _0"></span>，由于服务器端存储了<span class="_ _0"></span>不同码率版本的视</div><div class="t m0 x7 h8 y5f ff4 fs4 fc1 sc0 ls0 ws0">频分段<span class="ff1">,</span>用户可随时根<span class="_ _0"></span>据信道带宽的变化情况<span class="_ _0"></span><span class="ff1">,</span>请求不同质量<span class="_ _0"></span>的视频数据<span class="ff1">,</span>实<span class="_ _0"></span>现平</div><div class="t m0 x7 h8 y60 ff4 fs4 fc1 sc0 ls0 ws0">滑播放<span class="ff1">,</span>提高网络资源的利用效率。<span class="ff1"> </span></div><div class="t m0 xa h8 y61 ff4 fs4 fc0 sc0 ls0 ws0">但是，<span class="_ _3"></span>视频播放业务对网络有着严格的要求，<span class="_ _3"></span>由于无线网络带宽资源通常有</div><div class="t m0 x7 h8 y62 ff4 fs4 fc0 sc0 ls0 ws0">限，<span class="_ _6"></span>且不稳定，<span class="_ _6"></span>以及无线信道状况波动等原因将会影响视频数据的传输，<span class="_ _6"></span>造成初</div><div class="t m0 x7 h8 y63 ff4 fs4 fc0 sc0 ls0 ws0">始缓冲峰值速率低，端到端环回时间（<span class="ff1">E2E <span class="_ _5"></span>RTT</span>）长，平均下载速率低，抖动甚</div><div class="t m0 x7 h8 y64 ff4 fs4 fc0 sc0 ls0 ws0">至数据包的丢失等情况，<span class="_ _6"></span>造成初始缓冲时间长，<span class="_ _6"></span>播放过程出现卡顿等问题，<span class="_ _6"></span>影响</div><div class="t m0 x7 h8 y65 ff4 fs4 fc0 sc0 ls0 ws0">到用户对于视频的体验效果。<span class="ff1"> </span></div><div class="t m0 xa h8 y66 ff1 fs4 fc0 sc0 ls0 ws0"> </div><div class="t m0 x7 h8 y67 ff1 fs4 fc0 sc1 ls0 ws0">1.2 <span class="ff4">问题<span class="_ _0"></span>提出</span> </div><div class="t m0 xa h8 y68 ff4 fs4 fc1 sc0 ls0 ws0">对于这种无线网络视频流服务来说，<span class="_ _8"></span>原始视频序列在经过服务器编码以及网</div><div class="t m0 x7 h8 y69 ff4 fs4 fc1 sc0 ls0 ws0">络传输，<span class="_ _3"></span>最后到移动终端进行解码播放的过程中，<span class="_ _3"></span>影响用户体验的主要因素将会</div></div><a class="l" rel='nofollow' onclick='return false;'><div class="d m1"></div></a></div><div class="pi" data-data='{"ctm":[1.611792,0.000000,0.000000,1.611792,0.000000,0.000000]}'></div></div>
<div id="pf5" class="pf w0 h0" data-page-no="5"><div class="pc pc5 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/62bb3b46405aad31f7132f9f/bg5.jpg"><div class="c x0 y1 w2 h0"><div class="t m0 x8 h2 y2 ff1 fs0 fc0 sc0 ls0 ws0">2 </div><div class="t m0 x7 h8 y6a ff4 fs4 fc1 sc0 ls0 ws0">产生在网络传输阶段，<span class="_ _8"></span>又由于用户体验主观表现在<span class="_ _0"></span>初始缓冲等待时间和在视频播</div><div class="t m0 x7 h8 y6b ff4 fs4 fc1 sc0 ls0 ws0">放过程中的卡顿缓冲时间上，<span class="_ _2"></span>因此我们可以通过初始缓冲时延与卡顿时长占比作</div><div class="t m0 x7 h8 y6c ff4 fs4 fc1 sc0 ls0 ws0">为评价用户视频体验的关键指标来定量评价用户体验。<span class="ff1"> </span></div><div class="t m0 xa h8 y6d ff4 fs4 fc1 sc0 ls3 ws0">研究表明影响初始缓冲时延和卡顿时长占比的主要因素有初始缓冲峰值速</div><div class="t m0 x7 h8 y6e ff4 fs4 fc1 sc0 ls0 ws0">率、播放阶段平均下载速率、端到端环回时间（<span class="ff1">E2E <span class="_ _5"></span>RTT</span>）以及视频参数。由于</div><div class="t m0 x7 h8 y6f ff4 fs4 fc0 sc0 ls0 ws0">无线宽带网络资源有限，<span class="_ _2"></span>并且网络侧变量会在很大程度上影响视频的播放质量与</div><div class="t m0 x7 h8 y70 ff4 fs4 fc0 sc0 ls0 ws0">用户的体验效果，<span class="_ _0"></span>所以为了提高视频播<span class="_ _0"></span>放流畅度、便于优化网<span class="_ _0"></span>络视频观看体验，</div><div class="t m0 x7 h8 y71 ff4 fs4 fc0 sc0 ls0 ws0">对网络侧变量<span class="_ _9"></span><span class="fc1">（初始缓冲峰值速率、<span class="_ _10"></span>播放阶段平均下载速率、<span class="_ _9"></span><span class="ff1">E2E <span class="_ _6"></span>RTT)<span class="_ _0"></span><span class="ff4">与用户体</span></span></span></div><div class="t m0 x7 h8 y72 ff4 fs4 fc1 sc0 ls0 ws0">验评价变量<span class="_ _9"></span>（初始缓冲时延、<span class="_ _9"></span>卡顿时长占比）<span class="_ _9"></span>之间展开研究，<span class="_ _9"></span>这将有利于提高网</div><div class="t m0 x7 h8 y73 ff4 fs4 fc1 sc0 ls0 ws0">络侧服务质量，带来更好的视频体验效果<span class="fc0">。<span class="ff1"> </span></span></div><div class="t m0 x7 h8 y74 ff1 fs4 fc0 sc0 ls0 ws0"> </div><div class="t m0 x7 h8 y75 ff1 fs4 fc0 sc1 ls0 ws0">1.3 <span class="ff4">要解<span class="_ _0"></span>决的问题</span> </div><div class="t m0 x7 h8 y76 ff1 fs4 fc0 sc0 ls0 ws0"> 1. <span class="_ _5"></span><span class="ff4">通过实验数据，<span class="fc1">建立初始缓冲时延与网络侧变量（初始缓冲峰值速率，</span></span></div><div class="t m0 x7 h8 y77 ff4 fs4 fc1 sc0 ls0 ws0">播放阶段平均下载速率，<span class="ff1">E2E RTT)</span>之间的函数关系。<span class="ff1"> </span></div><div class="t m0 xa h8 y78 ff1 fs4 fc1 sc0 ls0 ws0">2. <span class="_ _5"></span><span class="ff4 fc0">通过实验数据，<span class="fc1">建立卡顿时长占比与网络侧变量（初始缓冲峰值速率，</span></span></div><div class="t m0 x7 h8 y79 ff4 fs4 fc1 sc0 ls0 ws0">播放阶段平均下载速率，<span class="ff1">E2E RTT)</span>之间的函数关系。<span class="ff1"> </span></div><div class="t m0 xa h8 y7a ff1 fs4 fc1 sc0 ls0 ws0">3. <span class="_ _5"></span><span class="ff4">验证模型的可用性，检验模型的正确性，并提出如何匹配网络带宽和视</span></div><div class="t m0 x7 h8 y7b ff4 fs4 fc1 sc0 ls0 ws0">频质量，使用户观看平滑流畅的视频，提高用户视频体验的相关改进意见。<span class="ff1"> </span></div><div class="t m0 x7 h8 y7c ff1 fs4 fc0 sc1 ls0 ws0"> </div><div class="t m0 xc h3 y7d ff4 fs1 fc0 sc1 ls0 ws0">二、问题分析<span class="ff1"> </span></div><div class="t m0 xa h8 y7e ff4 fs4 fc0 sc0 ls0 ws0">问题<span class="_ _d"> </span><span class="ff1">1<span class="_ _d"> </span></span>分析：<span class="_ _11"></span>首先对初始缓冲加载阶段进行了解，<span class="_ _11"></span>之后对实验数据进行筛选，</div><div class="t m0 x7 h8 y7f ff4 fs4 fc0 sc0 ls0 ws0">结合<span class="_ _7"> </span><span class="ff1">matlab<span class="_ _7"> </span></span>软件并利用插值拟合、皮尔森相关性等分析方法，寻找初始缓冲时</div><div class="t m0 x7 h8 y80 ff4 fs4 fc0 sc0 ls0 ws0">延与网络侧变量之间的关系，<span class="_ _3"></span>进而建立简单函数关系并逐步拓展，<span class="_ _3"></span>对模型进行误</div><div class="t m0 x7 h8 y81 ff4 fs4 fc0 sc0 ls0 ws0">差分析，<span class="_ _3"></span>寻找产生误差的可能原因并逐步优化改进模型，<span class="_ _3"></span>得出优化后的初始缓冲</div><div class="t m0 x7 h8 y82 ff4 fs4 fc0 sc0 ls0 ws0">时延映射模型，并检验模型的正确性、合理性，最后讨论模型的优缺点。<span class="ff1"> </span></div><div class="t m0 xa h8 y83 ff4 fs4 fc0 sc0 ls0 ws0">问题<span class="_ _d"> </span><span class="ff1">2<span class="_ _d"> </span></span>分析：<span class="_ _3"></span>首先通过查阅相关资料，<span class="_ _3"></span>分析实验数据得出了影响卡顿时长占</div><div class="t m0 x7 h8 y84 ff4 fs4 fc0 sc0 ls0 ws0">比的网络端因子，<span class="_ _0"></span>然后从不同角度出发<span class="_ _0"></span>建立了两个模型并在模<span class="_ _0"></span>型之间进行优选，</div></div></div><div class="pi" data-data='{"ctm":[1.611792,0.000000,0.000000,1.611792,0.000000,0.000000]}'></div></div>
