臺灣博碩士論文加值系統

Big Blue Button是一個開放源視訊會議的軟體，這個軟體內有多種功能，如:桌面分享、視訊分享、音訊分享、PPT或PDF分享…等等。Big Blue Button採用Adobe的Screen Video Codec2(簡稱SVC2)桌面分享視訊壓縮規範來進行桌面分享。
本論文在不改變SVC2串流格式下，是針對該軟體進行改進，改進方法，包括了畫面變化偵測機制的改進、畫面重傳時機的選擇、色彩量化的使用、畫面縮小演算法的改進、畫面擷取管線化(pipeline)的使用、畫面擷取的型態轉型函數之更換等機制。實驗結果證明本論文提出的方法在圖框率與頻寬的使用上皆可獲得改善。

Big Blue Button (BBB) is open-source software for video-conferencing, which provides sharing functions for desktop, video, audio, PPT and PDF, etc. For the desktop sharing, BBB adopts an encoder tailored to the Screen Video Codec 2(SVC2) of Adobe’s standard.
The goal of this work is to improve the encoder performance of BBB desktop sharing, while keeping the output video stream conforming to SVC2. This work improves BBB in many aspects, including detection of frame change, decision of frame replenishment, quantization of color, reduction of frame scaling complexity, pipeline structure of screen capture, type conversion of the capture frames. Experiment results shows the frame rate and bandwidth is improved by our proposed method.

目 錄
摘 要 i
ABSTRACT ii
誌 謝 iii
目 錄 iv
表目錄 vi
圖目錄 viii
第一章 緒論 1
1.1 研究動機與目的 1
1.2 研究方法 3
1.3 研究貢獻 3
1.4 論文組織架構 4
第二章 相關背景知識 5
2.1 Big Blue Button相關介紹 5
2.1.1 BBB中桌面分享介紹 10
2.1.2 Key Frame與Inter Frame 10
2.1.3 流程介紹與流程圖 11
2.1.4 區塊處理 14
2.1.5 SVC2顏色量化 19
2.1.6 資料編碼格式 22
2.1.7 FLV檔案格式以及結構 24
第三章 本論文提出之修改方法 27
3.1 改善頻寬的方法 27
3.1.1 門檻值 27
3.1.2 逐點檢查 28
3.1.3 顏色量化 30
3.2 改善圖框率的方法 31
3.2.1 轉換型態 31
3.2.2 縮放方法修改 31
3.2.3 等待時間 32
3.2.4 管線化 33
第四章 實驗結果與討論 35
4.1 實驗環境 35
4.2 測試數據介紹 35
4.3 測試圖框率的方法 35
4.4 頻寬測試軟體(Wireshark) 36
4.5 測試方法 37
4.6 結果分析 38
第五章 結論 54
參考文獻 55

[1]S. Ichimura and Y. Matsushita, "Lightweight Desktop-Sharing System for Web Browsers," Third International Conference on Information Technology and Applications, 2005, pp. 136-141
[2]G. Kiss, “Using web conference system during the consultation hours”, 7th IEEE International Symposium on Applied Computational Intelligence and Informatics, 2012, Timisoara, Romania, 2012.
[3]G. Kiss, “Comparison of traditional and web-based education – case study ‘BigBlueButton’ ”, Proceedings of the 2012 International Symposium on Information Technology in Medicine and Education, Hokkaido, Japan, IEEE Catalog Number: CFP1253E-PRT ISBN:978-1-4673-2016-8, pp: 224-227, IEEE Xplore digital library Digital Object Identifier:10.1109/ITiME.2012.6291286, 2012.
[4]Adler32,[online] http://en.wikipedia.org/wiki/Adler-32
[5]BigBlueButton,[online] http://bigbluebutton.org/
[6]BigBlueButton Desktop Share,[online] https://code.google.com/p/bigbluebutton/wiki/ArchitectureOverview#Desktop_Sharing
[7]FLV File Format,[online] http://www.adobe.com/content/dam/Adobe/en/devnet/flv/pdfs/video_file_format_spec_v10.pdf
[8]Wireshark,[online] http://www.wireshark.org/
[9]Red5,[online] https://code.google.com/p/red5/