參數化空間音訊編解碼器的研究及其即時軟體實作

Abstract

數位家庭是未來資訊產業最重要的趨勢，由DVD 多聲道劇院音訊開始，相 信多聲道且低位元率的音訊必定是下一世代消費性電子需求的主流。除此之外， 也有愈來愈多新的多聲道音訊的應用產生，例如手持式的裝置或是車用系統，甚 至是數位音訊的廣播服務。這些新的應用都非常需要有一個好的音訊壓縮的方法 來達到多聲道、高品質且低位元率的需求。 事實上傳統的音效壓縮方式通常會隨著聲道的數目成等比例的增加，而以往 對多聲道音訊壓縮的演算法的位元率還是比單聲道音訊高得多，所以一種新的多 聲道音訊壓縮的演算法因應而生，那就是－參數化空間音訊編解碼演算法。參數 化空間音訊編解碼演算法能夠將多聲道的音訊做非常好的壓縮，使得位元率機乎 和單聲道音訊相同。 本論文將會深入研究探討參數化空間音訊編解碼演算法，在論文的前半部會 探討包括在空間聽覺上的學術背景以及各種參數化空間音訊編解碼演算法之間 的不同。而在論文的後半部會針對低複雜度、高音訊品質的參數化空間音訊編解 碼演算法的實做方式做深入討論。

The trend of information technology (IT) converges toward the digital home, driven by the DVD movie multi-channel audio sound, next generation digital multimedia content with high quality but low bit-rate multi-channel audio is surely to be the main stream in the near future. Furthermore, lots of the new multi-channel audio applications emerged in these years. For example, mobile applications, portable devices, automotive applications, such as car audio playback setups even digital audio broadcasting services, drive the demand of multichannel audio playback. A carefully designed audio coding mechanism which minimizes transmission costs or provides cost-efficient storage and gains best surround performance is therefore, of interest. In fact, the complexity of the traditional audio coding schemes scale with the number of audio channels, and the bitrate of legacy multi-channel coding techniques are still considerable higher than mono signal. Under this circumstance, a new imperative evolution of the digital audio coding scheme, the Parametric Spatial Audio Coding, is proposed. The Parametric Spatial Audio Coding is a promising approach which enables the transmission of multi-channel audio signals at data rates close to the rates used for the representation of mono or stereo (or more) audio signals. A thorough investigation of Parametric Spatial Audio Coding including spatial hearing backgrounds, differences between Parametric Spatial Audio Coding algorithms will be illustrated in the former part of this thesis. In the later part, it will present a detail discussion on low complexity with satisfactory listening quality implementation of a Parametric Spatial Audio Coding scheme.