MPEG-2/4 低複雜度先進音訊編碼演算法最佳化及在StrongARM平台上之實現

Abstract

這篇論文提出一套AAC編碼的最佳化演算法以及在AAC編碼系統中加入資料嵌入演算法的應用。最後將這兩套系統實現在一顆206MHz的32位元定點處理器StrongARM SA-1110上。實驗結果顯示，我們所提出的架構在實驗平台上可執行至少一倍速的壓縮。在AAC 編碼最佳化中，我們移除計算量龐大的長短窗轉換，簡化TNS及M/S立體聲編碼的控制流程，數學函式的簡化運算及較快速的量化模組，在MDCT的實現方式上，也採用了以快速演算法。為了彌補定點化過程中所產生的誤差，我們加入了頻寬控制及動態精確度的MDCT運算等。最後，為了進一步增加AAC檔案的功能性，並在AAC編碼系統中加入資料嵌入的應用。

In this thesis, we present an optimized AAC encoding scheme and also proposed a data embedded method integrated into AAC encoding system. Both of them are finally realized on a 32-bit fixed-point processor, StrongARM SA-1110. Experimental result shows that at least 1 encoding speed is achieved. In the AAC encoding algorithm, we propose several approaches including the removal of block switching, fast MDCT, simplified TNS, simplified M/S stereo coding, mathematical function optimization and fast quantization. To compensate the error caused by fixed-point conversion, a bandwidth control and a dynamic data precision MDCT are applied. Finally, a data embedded method is implemented to further increase its utility.