隨著網路技術快速的發展、網路頻寬的增加，在網際網路上傳輸多媒體的應用越來越廣泛且受到重視。傳統視訊壓縮方法的目標是要在一固定的位元率對畫面視覺效果作最佳化。然而，在網際網路上每個使用者的頻寬都不一樣而且有效頻寬會隨著時間變化，因此傳統視訊壓縮方法並不適用於網際網路上的傳輸。為了能夠應付頻寬的變化，視訊位元流 (video bitstream) 即使因為網路頻寬的限制而被截斷也必須能夠由收到的部分位元流解碼回視訊畫面且接到的位元數越多，相對的畫質也就越好。這個特性也就是所謂的精緻可伸縮性 (fine granularity scalability)。
目前MPEG委員會採用將量化後的差值作數位餘弦轉換再對位元平面作編碼 (bitplane coding)。在本篇論文中，我們提出以嵌入式量化器 (embedded quantizer) 為基底的編碼方法來達成精緻可伸縮性。嵌入式量化器的主要概念是將餘弦轉換過的係數經過一次量化後，將此量化過的數值分割為好幾個部分，再對每個部分個別作編碼。如果每個部分都能夠被接收到而且正確解碼的話，那整體的表現就會跟沒有經過分割是一樣的。

本篇論文中對此以嵌入式量化器為基底的編碼方法作探討及模擬。此方法可以確實達成精緻可伸縮性，雖然編碼效能僅僅趨近於目前MPEG委員會所採用的方法。我們相信如果進一步對此編碼方法作位元流結構 (bitstream syntax) 作最佳化的話，其編碼效能必能有所增進。

In recent years, the need of transmitting multimedia contents over TCP/IP on the Internet is growing rapidly. The conventional video compression techniques are concentrated on optimizing the coding performance at a given bitrate. However, these video coding techniques are not suitable for multimedia streaming over the Internet due to the bandwidth differences of heterogeneous networks and the bandwidth variations with time. In order to transmit multimedia contents over the Internet, the bitstream should be partially decodable at any bitrate to reconstruct a video signal with the optimized quality at that bitrate. This is the objective of fine granularity scalability (FGS) video coding techniques in the Amendment of MPEG-4.
The bitplane coding of the DCT residues was adopted by the MPEG committees. In this thesis, we propose an embedded-quantizer based encoder to achieve fine granularity scalability. The concept of embedded-quantizer is to quantize the DCT coefficients once, and then separate the quantized coefficients into several parts and code each separated part individually. If all separated parts can be received and decoded, the performance will be the same as if there were no separation.

The performance of the embedded-quantizer based encoder is evaluated. We proved that this structure could achieve fine granularity scalability although the performance is merely approaching the structure provided by FGS reference software. We believe that its performance could be better if the bitstream syntax was optimized.

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