H.264 CAVLC管線架構視訊編碼器設計

H.264 CAVLC Video Encoder Design with Pipeline Structure

王夏果(Hsia-Kuo Wang)

指導教授 ： 傅楸善

國立臺灣大學/電機資訊學院/資訊工程學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.00204

摘要

CAVLC的全名為Context-Adaptive Variable Length Coding. Context-Adaptive的意義, 即在於對各種不同的context, 使用不同的table進行encode, 以針對各種情況有效縮短輸出bit stream長度。在H. 264中, CAVLC用於encode integer DCT (Discrete Cosine Transform) 轉換後的matrix係數。首先, CAVLC先擷取出目標matrix的非零coefficient總數、Trailing one (代表以zigzag方式從左上角開始, 反覆掃瞄所有非零coefficient時, 在尾端的+1或-1) 總數、等於0的coefficient總數、各zero run (以zigzag順序掃瞄時, 連續出現的0) 等參數, 作為查表時的index, 而非直接encode所有coefficient. 同時, CAVLC分別針對了不同的block type (4*4, 2*4, 2*2三種block) 設計了不同的table.

本篇論文提出了一種新的設計方式, 以公定規格之CAVLC為基礎, 進一步設計出節省計算時間、儲存空間, 同時具有最小面積之IC晶片。

關鍵字

視訊編碼器 ； 管線架構

並列摘要

This paper proposes a new method of CAVLC (Context Adaptive Variable Length Coding) encoder design. To achieve best hardware utilization, this function is divided into 8 parts: Stage1, nCBuffer, LevelBuffer, writeSE_LEVEL_VLC, writeSE_Total0, writeSE_0Run, Mux_5to1, and OutputUnit. The memory cost is fewer with smaller buffer and carefully reduced lookup tables.
Besides, the two-stage pipelined structure improves the data throughput. Thus, this design is suitable for the real-time H.264/AVC video encoding/decoding on digital cameras.

並列關鍵字

H. 264 ； CAVLC ； Encoder

參考文獻

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[2] C. D. Chien, K. P. Lu, Y. H. Shih, and J. I. Guo, “A High Performance CAVLC Encoder Design for MPEG-4 AVC/H.264 Video Coding Applications”, Proceedings of International Symposium on Circuits and Systems, Island of Kos, Greece, pp. 3838-3841, 2006.

[4] Joint Video Team, “Reference Software JM 12.2,” http://iphome.hhi.de/suehring/tml/, 2007.

[5] ITU, “Advanced Video Coding,” ITU-T Rec. H.264 and ISO/IEC 11496-10, 2003.