在不同的網路環境中進行視訊傳輸，FGS是一個很有用的技術。根據發送端與接收端之間的可用頻寬，FGS可以動態的調整要傳送的影片資料量，使得接收端能得到相對應品質的影片。然而，為了適合網路傳輸，我們通常會利用固定位元速率(CBR)編碼的技術，來壓縮基本的影片(base layer video)。以此技術壓縮的影片，雖然頻寬得到固定，但卻會有品質不穩定的問題。因此，當可用頻寬大於基本的影片資料量時，我們利用FGS可以動態調整影片資料量的特性，提出了三個方法來穩定影片品質。這些方法的目標，是要減小每張影像之間，以及同一張影像不同區域之間品質的差異。第一個方法標記每一層bit-plane的品質等級，讓每張影像在傳送時可以知道要傳送幾層bit-plane才會有相同的影片品質。第二個方法我們改變了block的傳送順序，讓同一張影像之中，品質較低的區域可以比較早提昇其品質。第三個方法我們利用較高品質的影像，來作為壓縮下一張影像的參考，此方法不但能使得頻寬較低時的影像品質得到穩定，而且還可以提昇FGS的壓縮效率。實驗結果證明了上述的方法都有不錯的效果。另外，這些方法的運算量都非常的低，因此上述的方法都可以應用在需要即時編碼與解碼的系統之中。

Fine granularity scalability (FGS) is a useful technique to support video streaming through heterogeneous networks. According to available network bandwidth between the sender and the receiver, the FGS enhancement layer bitstream can be truncated at any point to provide relative video quality. By utilizing the characteristic of enhancement layer bitstream, this thesis proposes three schemes to smooth the quality of FGS video. Our target is to reduce the inter-frame and intra-frame quality variation. We propose to label each bit-plane according to its quality level so that the server can decide how many bit-planes should be transmitted to keep every frame has the same quality. Also, we change the block transmission order according to its sum of DCT residuals. By this approach, the lower quality parts in a frame can be enhanced earlier. We also present a predicting method by referring to the enhancement layer data. This method not only smoothes the video quality at low bitrate but also improve the coding efficiency of FGS. Experimental results show our methods take greatly effects on reducing the inter-frame and intra-frame quality variation. Further, the computational complexity of these three methods is very small so that our methods can be applied to the real time constrained systems.

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[4] Xi Min Zhang; Vetro, A.; Shi, Y.Q.; Huifang Sun; “Constant quality constrained rate allocation for FGS-coded video,” Circuits and Systems for Video Technology, IEEE Transactions on, Volume: 13, Issue: 2, Feb. 2003 Pages: 121 – 130.

[5] Lifeng Zhao; Jong Won Kim; Kuo, C.-C.J.; “Constant quality rate control for streaming MPEG-4 FGS video,” Circuits and Systems, 2002. ISCAS 2002, IEEE International Symposium on, Volume: 4, 26 – 29 May 2002 Pages: IV-544 – IV-547 vol.4.

[6] Won-Sik Cheong; Kyuheon Kim; Gwang Hoon Park; Young Kwon Lim; Yoon Jin Lee; and Jinwoong Kim; “FGS Coding Scheme with Arbitrary Water Ring Scan Order”, ISO/IEC JTC1/SC29/WG11, MPEG01/M7442, July 2001.

[7] Jian Zhou; Huairong Shao; Chia Shen; Ming-Ting Sun; “FGS enhancement layer truncation with minimized intra-frame quality variation,” International Conference on Multimedia and Expo 2003.

[8] Wei Ding; Bede Liu; “Rate control of MPEG video coding and recording by rate-quantization modeling,” Circuits and Systems for Video Technology, IEEE Transactions on, Volume: 6, Issue: 1, Feb. 1996 Pages: 12 – 20.

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[10] Yi-Shin Tung; Ja-Ling Wu; Po-Kang Hsiao; Kan-Li Huang; “An efficient streaming and decoding architecture for stored FGS video,” Circuits and Systems for Video Technology, IEEE Transactions on, Volume: 12 Issue: 8, Aug. 2002 Page(s): 730 – 735.

[11] Hsiang-Chun Huang; Chung-Neng Wang; Tihao Chiang; “A robust fine granularity scalability using trellis-based predictive leak,” Circuits and Systems for Video Technology, IEEE Transactions on, Volume: 12 Issue: 6, June 2002 Page(s): 372 – 385.

[12] Feng Wu; Shipeng Li; Ya-Qin Zhang; “A framework for efficient progressive fine granularity scalable video coding,” Circuits and Systems for Video Technology, IEEE Transactions on, Volume: 11 Issue: 3, March 2001 Page(s): 332 – 344.