?? h_264視頻編碼傳輸?shù)膓os特性分析（一） - it專(zhuān)欄.htm
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style="LINE-HEIGHT: 150%">，</SPAN><SPAN style="LINE-HEIGHT: 150%">Video Coding
Layer</SPAN><SPAN style="LINE-HEIGHT: 150%">）和網(wǎng)絡(luò)提取層（</SPAN><SPAN
style="LINE-HEIGHT: 150%">NAL</SPAN><SPAN
style="LINE-HEIGHT: 150%">，</SPAN><SPAN style="LINE-HEIGHT: 150%">Network
Abstraction Layer</SPAN><SPAN
style="LINE-HEIGHT: 150%">）。其中，視頻編碼層獨(dú)立于網(wǎng)絡(luò)，主要包括核心壓縮引擎和塊、宏塊和片的語(yǔ)法句法定義。通過(guò)引入一系列新特性，不但使</SPAN><SPAN
style="LINE-HEIGHT: 150%">H.264</SPAN><SPAN
style="LINE-HEIGHT: 150%">的編碼壓縮效率提升了近</SPAN><SPAN
style="LINE-HEIGHT: 150%">1</SPAN><SPAN
style="LINE-HEIGHT: 150%">倍，而且多種錯(cuò)誤恢復(fù)工具又增強(qiáng)了視頻流的頑健性。網(wǎng)絡(luò)提取層的主要功能是定義數(shù)據(jù)的封裝格式，把</SPAN><SPAN
style="LINE-HEIGHT: 150%">VCL</SPAN><SPAN
style="LINE-HEIGHT: 150%">產(chǎn)生的比特字符串適配到各種各樣的網(wǎng)絡(luò)和多元環(huán)境中。涉及片級(jí)別以上的語(yǔ)法定義，包括獨(dú)立片解碼所要求的數(shù)據(jù)表示，類(lèi)似以往視頻壓縮標(biāo)準(zhǔn)中的圖像和頭部順序數(shù)據(jù)；防止競(jìng)爭(zhēng)的編碼；附加的增強(qiáng)信息以及編碼片的比特字符串。</SPAN></DIV>
<DIV style="TEXT-INDENT: 21pt; LINE-HEIGHT: 150%" align=left><SPAN
style="LINE-HEIGHT: 150%">H.264</SPAN><SPAN
style="LINE-HEIGHT: 150%">從框架結(jié)構(gòu)上將</SPAN><SPAN
style="LINE-HEIGHT: 150%">NAL</SPAN><SPAN
style="LINE-HEIGHT: 150%">與</SPAN><SPAN
style="LINE-HEIGHT: 150%">VCL</SPAN><SPAN
style="LINE-HEIGHT: 150%">分離，主要有兩個(gè)目的：</SPAN></DIV>
<DIV style="TEXT-INDENT: 21pt; LINE-HEIGHT: 150%" align=left><SPAN
style="LINE-HEIGHT: 150%">其一，可以定義</SPAN><SPAN
style="LINE-HEIGHT: 150%">VCL</SPAN><SPAN
style="LINE-HEIGHT: 150%">視頻壓縮處理與</SPAN><SPAN
style="LINE-HEIGHT: 150%">NAL</SPAN><SPAN
style="LINE-HEIGHT: 150%">網(wǎng)絡(luò)傳輸機(jī)制的接口，這樣允許視頻編碼層</SPAN><SPAN
style="LINE-HEIGHT: 150%">VCL</SPAN><SPAN
style="LINE-HEIGHT: 150%">的設(shè)計(jì)可以在不同的處理器平臺(tái)進(jìn)行移植，而與</SPAN><SPAN
style="LINE-HEIGHT: 150%">NAL</SPAN><SPAN
style="LINE-HEIGHT: 150%">層的數(shù)據(jù)封裝格式無(wú)關(guān)；<BR></SPAN><SPAN
style="FONT-SIZE: 10.5pt"> 其二，</SPAN><SPAN
style="FONT-SIZE: 10.5pt">VCL</SPAN><SPAN
style="FONT-SIZE: 10.5pt">和</SPAN><SPAN
style="FONT-SIZE: 10.5pt">NAL</SPAN><SPAN
style="FONT-SIZE: 10.5pt">都被設(shè)計(jì)成工作于不同的傳輸環(huán)境，異構(gòu)的網(wǎng)絡(luò)環(huán)境并不需要對(duì)</SPAN><SPAN
style="FONT-SIZE: 10.5pt">VCL</SPAN><SPAN
style="FONT-SIZE: 10.5pt">比特流進(jìn)行重構(gòu)和重編碼。下面分別就</SPAN><SPAN
style="FONT-SIZE: 10.5pt">VCL</SPAN><SPAN
style="FONT-SIZE: 10.5pt">和</SPAN><SPAN
style="FONT-SIZE: 10.5pt">NAL</SPAN><SPAN
style="FONT-SIZE: 10.5pt">對(duì)于視頻傳輸?shù)?lt;/SPAN><SPAN
style="FONT-SIZE: 10.5pt">QoS</SPAN><SPAN
style="FONT-SIZE: 10.5pt">進(jìn)行分析。</SPAN></DIV>
<DIV style="TEXT-INDENT: 21pt; LINE-HEIGHT: 150%" align=left><SPAN
style="FONT-SIZE: 10.5pt"> </SPAN><SPAN
style="FONT-SIZE: 10.5pt">相關(guān)文檔：《<A
href="http://blog.csdn.net/fengyv/archive/2006/05/08/712985.aspx"><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">關(guān)于</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋體">H.264</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">視頻編碼傳輸?shù)?lt;/SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋體">QoS</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">特性分析（一）</SPAN></A>》</SPAN></DIV>
<DIV style="TEXT-INDENT: 21pt; LINE-HEIGHT: 150%" align=left><SPAN
style="FONT-SIZE: 10.5pt">
《<A href="http://blog.csdn.net/fengyv/archive/2006/05/08/713008.aspx"><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">關(guān)于</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋體">H.264</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">視頻編碼傳輸?shù)?lt;/SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋體">QoS</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">特性分析（二）</SPAN></A>》</SPAN></DIV>
<DIV style="TEXT-INDENT: 21pt; LINE-HEIGHT: 150%" align=left><SPAN
style="FONT-SIZE: 10.5pt">
《<A href="http://blog.csdn.net/fengyv/archive/2006/05/08/713025.aspx"><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">關(guān)于</SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋體">H.264</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">視頻編碼傳輸?shù)?lt;/SPAN><SPAN
lang=EN-US
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋體">QoS</SPAN><SPAN
style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋體; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">特性分析（三）</SPAN></A>》<BR></SPAN>上一篇：《<A
href="http://blog.csdn.net/fengyv/archive/2006/05/08/712631.aspx">H.264/AVC技術(shù)進(jìn)展及其務(wù)實(shí)發(fā)展策略思考</A>》</DIV>
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