以灰色多項式內插法為基礎之時間域錯誤隱藏方法

Temporal Error Concealment Based on Gray Polynomial Interpolation

熊冠傑(Kuan-chieh Hsiung)

指導教授 ： 謝政動

朝陽科技大學/資訊學院/資訊工程系/碩士(2009年)

摘要

今日以封包在網路通道傳送壓縮視訊已經相當普遍。然而，如果封包傳送在易錯的網路通道時，可能會造成封包遺失，進而影響到壓縮視訊的品質。例如，一個封包的遺失可能導致整張畫面不能解碼，也可能會傳遞錯誤到後續畫面。為了解決這個問題，所以在解碼端加入錯誤隱藏方法來解決因封包遺失產生解碼畫面品質不良的問題。也就是說，利用錯誤隱藏方法來修復封包遺失所造成畫面中的錯誤區塊。
本論文提出一個基於灰色多項式內插法(Grey Polynomial Interpolation, GPI)之時域錯誤隱藏方法(Temporal Error Concealment, TEC)，簡稱為TEC/GPI (TEC with GPI)。在TEC/GPI方法中，分為兩個部分：錯誤區塊檢測與錯誤區塊修復。在錯誤區塊檢測方面，我們分為規則錯誤區塊和不規則錯誤區塊的檢測方法，在錯誤區塊修復方法，我們使用邊界匹配演算法(Boundary Matching Algorithm, BMA)在向前和向後去找到可利用的參考畫面中, 再尋找參考區塊。根據錯誤區塊檢測找到錯誤區塊的位置與在前後張參考畫面找到的參考區塊，接著我們就使用TEC/GPI來修復錯誤區塊。
最後，我們以模擬來驗證所提出的TEC/GPI方法，並且與其他相關錯誤隱藏方法進行比較。本論文以H.264為例子進行模擬，結果顯示不論在客觀的PSNR或是主觀的視覺品質方面，平均而言我們所提的TEC/GPI錯誤隱藏方法均優於其他方法。

關鍵字

錯誤隱藏 ； H.264 ； 錯誤區塊檢測 ； 灰色多項式內插法

並列摘要

Nowadays, transmission of compressed video data by packets is quite common over the network channels. However, there is an inevitable problem in the packet-based transmission, that is, packet loss. The packet loss generally affects the visual quality of decoded video significantly. To deal with the problem, the scheme called error concealment is sought. The objective of error concealment is to estimate the blocks in the lost packets through available decoded frames and blocks. By this doing, the error blocks may be concealed and thus the visual quality is enhanced.
The thesis presents a temporal error concealment (TEC) based on grey polynomial interpolation (GPI). The proposed approach is called temporal error concealment with grey polynomial interpolation and abbreviated as TEC/GPI. The proposed TEC/GPI approach consists of two parts: error block detection and error block concealment.
In the error block detection, two types of error blocks are detected: error blocks with regular boundary and with irregular boundary. Once the error blocks are found, then the error block concealment follows. The error block concealment involves two steps. First, locate the boundary of error blocks by the boundary matching algorithm (BMA) to find available frames and blocks which are good for the error concealment. Second, by the good blocks the proposed TEC/GPI is performed to obtain the estimated blocks which are then used to replace the corresponding error blocks.
To verify the proposed TEC/GPI approach, several video files are provided as examples where H.264 is employed and packet loss with various rates is under consideration. The simulation results indicate that the proposed TEC/GPI outperforms the compared scheme in H.264, both in objective and subjective assessments.

並列關鍵字

grey polynomial interpolation ； H.264 ； error concealment ； error block detection

參考文獻

[1] ITU-T Recommendation H.261, Video CODEC for audiovisual services at px64 kbit/s 1993.

[2] ITU-T Recommendation H.263, Video coding for low bit ratecommunication, Version 2 1998.

[3] ISO/IEC 14496-10 and ITU-T Rec.H.264, Advanced Video Coding 2003.

[7] Fan Zhai, Y. Eisenberg, T.N. Pappas, R. Berry, A.K Katsaggelos, “Rate-distortion optimized hybrid error control for real-time packetized video transmission, “IEEE Transactions on Image Processing, Vol. 15, pp. 40-53, Jan. 2006.

[8] Y. Wang and Q.-F. Zhu, “Error control and concealment for video communication: A Review,” Proceedings of IEEE, Vol. 86, No. 5, pp. 974-997, May 1998.