Ogg Vorbis Audio Codec Technology Analysis And Applied To Improve

Digital Audio Coding is one of the most extensively used digital technologies. Due to the individual shortcomings, traditional MPEG-1 Layer III (MP3) technique and a high-performance audio coding technique--Advanced Audio Coding (AAC) have been strongly challenged by a newly developing audio technique: Ogg Vorbis. Vorbis coding algorithm can provide high quality audio compression with advanced Perceptual Coding and Transform Coding technologies; and because of its completely open and non-patent, Vobis has attracted more and more attentions by music industrial and audio users.In this paper, I mainly developed the theory of open-source Ogg Vorbis audio technique including its coding and decoding procedure. The theory was introduced in sections according to different functional modules. After analysis and derivation on one of Vorbis's core process parts, a unified implement structure was presented. Meanwhile, some modifications were made on source-code to improve the audio quality. Finally some experiments were conducted to compare and summarize the coding performance of Ogg Vorbis, MP3 and AAC. The achievement of modifications on source-code was summarized as well.Chapter One briefly introduced current developing status of audio coding techniques and the structure of this paper; then Chapter Two shortly described the history of Ogg Vorbis and its technical process flow; the data process and parameters calculations before Vorbis quantization were discussed in Chapter Three; and the details about Vorbis quantization were shown in Chapter Four; the following Chapter Five researched the process of Vorbis decoding; in Chapter Six, I derived and provided a unified implement structure on MDCT and modified the source-code; Chapter Seven is about some experiments where I compared and analyzed to finally present a summary on Ogg Vorbis encoding performance and the results on code modifications.