運用碼率失真函數於分散式視訊編碼系統 之區塊模式選擇

隨著科技不斷的進步，使用者對於多媒體的需求也會有所不同，有些編碼端需求是成本低廉、低耗電量以及資料即時傳輸，為了符合此類系統的需求，分散式訊源處理 (Distributed Source Coding, DSC) 常被提出以解決此類問題，若應用於視訊處理上，即稱為分散式視訊處理 (Distributed Video Coding, DVC)，本篇論文在探討區塊模式選擇，先前Threshold-based DVC是利用絕對值誤差總和(Sum of Absolute Difference, SAD) 和變異數 (Variance)，設下門檻值當成模式判斷的依據，只可選擇兩種區塊編碼模式，分別是Intra mode和WZ mode，但如何準確的選擇區塊模式，一直是尚未徹底討論的議題。本篇論文利用Rate-distortion (R-D) function當成模式選擇的依據，並且加以改善，除了修正 Rate 與 Distortion 計算方式，也討論Lagrange multiplier參數的設定，目的是為了調整碼率和失真之間的關係，除了保有Threshold-based DVC兩種編碼模式 (Intra 與 WZ)，另外還提出了Skip mode，三種編碼模式分別透過各自的R-D function所計算的數值作比較，可以得到較合理的區塊模式選擇，相對於Threshold-based DVC，可以得到較佳的編碼效能， R-D function區塊模式選擇相較於Threshold-based區塊模式選擇，可節省了2.61% 的碼率，解碼複雜度也可大幅降低。

關鍵字

區塊模式選擇；位元與失真函數；分散式視訊編碼； Wyner-Ziv 理論

並列摘要

Distributed Source Coding (DSC) is one of famous techniques to meet requirements of low-cost and low-power encoder in some emerging techniques. This architecture applied for multimedia technology is called Distributed Video Coding (DVC). Accurate block mode decision is one of essential schemes to improve the coding performance. The threshold-based DVC applies three conditions to determine the block mode (Intra/WZ modes). No matter the low-rate or high-rate scenario, the threshold-based DVC uses fixed block mode decision. In this thesis, we proposed Rate-Distortion function(R-D function) for block mode decision along with a new Skip mode. We calculate the cost of three block mode by the corresponding R-D functions and determine the block mode with the minimum cost criteria. The R-D function DVC can perform about 2.61% rate reduction, or about 0.17 dB quality gain, compared with the threshold-based DVC. Moreover, the decoding throughput can be increased .

並列關鍵字

Block Mode Decision ； Rate Distortion Function ； Distributed Video Coding ； Wyner-Ziv theorem

參考文獻

[1] D. Slepian, and J. K. Wolf, “Noiseless Coding of Correlated Information Sources,” IEEE Transaction on Information Theory, Vol. 19, No. 4, pp. 471-480, July 1973.

[2] D. Wyner, J. Ziv, “The Rate-Distortion Function for Source Coding with Side Information at The Decoder,” IEEE Transaction on Information Theory, Vol. 22, No. 1, pp. 1-10, January 1976.

[3] C. Pang, O. C. Au, J. Dai, and F. Zou, “Frame Complexity Guided Lagrange Multiplier Selection for H.264 Intra-Frame Coding,” IEEE Signal Process. Lett., vol. 18, no. 12, December, 2011.

[4] X. Jing, L. P. Chau, and W. C. Siu,"Frame Complexity-Based Rate-Quantization Model for H.264/AVC Intraframe Rate Control," IEEE Signal Process.Lett .Vol. 15,pp.373 -376, 2008.

[6] Kubasov, J. Nayak, and C. Guillemot, "Optimal Reconstruction in Wyner-ziv Coding with Multiple Side Information," Multimedia Signal Processing(MMSP),pp.183-186,October.2007

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運用碼率失真函數於分散式視訊編碼系統之區塊模式選擇

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