在 MPEG 及 AC-3 音訊壓縮之設計

Abstract

ISO MPEG 1/2 及 Dolby AC-3 兩個標準廣泛應用於網路無線通訊多媒體系統及電影工業. 本論文將針對MPEG-1/2 and AC-3的模組提出設計. 音訊壓縮器如 MPEG-1/2 及 AC-3 均由濾波器組, 音響心理學模型,位元分配器, 立體聲矩陣及量化器等模組所構成. 本論文將針對以上模組提出設計方法. 首先, 簡介並歸納使用於ISO MPEG 1/2 及 Dolby AC-3 的各式濾波器組並提出一個單一的快速演算法. 在音響心理學模型部分, 提出以混合式濾波器組取代原來MPEG的頻率分析器以獲得快速計算. 在位元分配器及量化器部分,提出有效率的MPEG 及 AC-3位元分配器. 本論文同時對於立體聲的音響心理壓縮提出方法以達到更好的音訊壓縮品質

ISO MPEG 1/2 and Dolby AC-3 are widely used in the network, wireless, multimedia system and video industry. This dissertation studies the design of audio standards: MPEG-1/2 and AC-3. The perceptual audio coder like MPEG-1/2 and AC-3 can be analyzed through filterbank, psychoacoustic model, stereo matrix, bit allocation/ quantization, and packing block. This dissertation considers the design for the filterbank, psychoacoustic model, stereo matrix, and bit allocation/ quantization. This dissertation summarizes the filterbanks adopted in coding standards and presents a unified fast algorithm for these filter banks. On the psychoacoustic models, the hybrid filterbank is proposed to replace to original frequency analyzer for MPEG audio standards to have efficient computing. On the bit allocation, we analyze the issues in bit allocation and present the efficient method. This dissertation also studies the stereo irrelevancy and presents the new method to achieve good quality.