| 摘要: | 隨著網路頻寬的增加以及安控產業的發展，傳統上要觀看安控系統所生成之歷史影像回放資料必需於Client端安裝客製化套件或使用IE ActiveX技術將播放器外掛元件嵌入運行之瀏覽器執行程序內，拜HTML5瀏覽器技術的進步，目前針對影音封裝格式已經可支援到以MPEG-4格式封裝H.264與AAC codec影音壓縮資料後直接於瀏覽器上直接播放。透過前端Media Server以RTSP協定溝通之網路攝影機，將封裝於RTP封包Payload內視頻與音頻封包分離出來後根據ISO/IEC 14496-12 Base Media File Format規範打包成MPEG-4檔。然而，實務上會發現不同廠牌之攝影機在Video與Audio的codec與profile都選擇相同的條件下，有些錄影檔透過網頁瀏覽器原生HTML5播放器直接開啟會產生無法播放問題。後來透過工具分析MPEG-4封裝結構內之Moov Box，針對不同種類網路攝影機所產生之錄製封裝結果，發現Moov box結構下之stts box資訊會因在某種條件因素下產生不合適之資訊，該資訊的存在對於傳統使用獨立播放器（例如VLC Player）播放沒有問題，但是將該檔案透過HTML5瀏覽器播放器播放時則會出現無法播放之異常。本研究共截取2020年總市占率占7成以上攝影機廠牌如海康、大華、安迅士、晶睿、奇偶、利凌部分型號設備進行驗證，透過本研究的修正流程可調整前述有問題的Moov Box內容，以達到單一平台兼容處理不同廠牌攝影機串流問題。;With the increase of network bandwidth and the development of the security control industry, traditionally, to view the historical video playback data generated by the security control system, it is necessary to install a customized package on the client side or use IE ActiveX technology to embed the external components of the player. In the browser execution program, thanks to the advancement of HTML5 browser technology, the video and audio packaging format can support H.264 and AAC codec video and audio compression data in MPEG-4 format and then directly play on the browser. The IP camera that communicates with the RTSP protocol through the front-end Media Server separates the video and audio packets encapsulated in the RTP packet payload and packs them into MPEG-4 files according to the ISO/IEC 14496-12 Base Media File Format specification. However, in practice, it is found that under the condition that the codec and profile of video and audio are the same for cameras of different brands, some video files can not be played when they are opened directly through the native HTML5 player of the web browser. Later, using tools to analyze the Moov Box in the MPEG-4 packaging structure, according to the recording and packaging results produced by different types of network cameras, it was found that the stts box information under the Moov box structure would produce inappropriate information under certain conditions. The existence of this information is no problem for traditional use of independent players （such as VLC Player） to play, but when the file is played through HTML5 browser players, there will be an exception that cannot be played. In this study, some models of camera manufacturers, such as Hikvision, Dahua, Axis, Vivotek, Geovision, and LILIN, which accounted for more than 70% of the market share in 2020, were used for verification. The above-mentioned can be corrected through the correction process of this study. The content of the Moov Box in question can be compatible with a single platform to handle the streaming problem of different brands of cameras. |
