标题: | MPEG-4 HE-AAC 中之高频调整模组设计 Design for High Frequency Adjustment Module in MPEG-4 HE-AAC |
作者: | 杨咏成 Yung-Cheng Yang 刘启民 Chi-Min Liu 资讯科学与工程研究所 |
关键字: | 高频调整;HE-AAC;HF adjustment |
公开日期: | 2005 |
摘要: | 高频调整模组是MPEG-4 HE-AAC中的核心模组,其目标在于回复高频重建讯号的音调度,使其如同原始讯号一般。两个决定性的问题为,如何准确的测量讯号的音调度,与如何决定共用的控制参数。控制参数之计算与音调度相关,其值将决定在解码端的增益大小与额外补偿之能量大小,换句话说,重建讯号的品质直接受到高频调整模组的影响。 本论文提出一有效率的方法来测量子频带讯号的音调度,使用线性预测并基于Levinson-Durbin演算法以自动调整预测等级,使其符合不同的讯号内容。进而探讨因控制参数之共用所造成的音讯失真,并提出如何有效地决定控制参数之方法。 High frequency adjustment module is the kernel module of spectral band replication (SBR) in MPEG-4 HE-AAC. The objective of high frequency adjustment is to recover the tonality of reconstructed high frequency signal as the original tonality. There are two crucial issues, the accurate measurement of tonality and the decision of shared control parameters. Control parameters, which are extracted according to signal tonality, will be used to determine gain control and energy level of additional components in decoder part. In other words, the quality of the reconstructed signal will be directly related to the high frequency adjustment module. In this thesis, an efficient method based on Levinson-Durbin algorithm is proposed to measure the tonality by linear prediction approach with adaptive orders to fit the different subband contents. Furthermore, the artifact due to the sharing of control parameter is investigated and the efficient decision criterion of control parameter is proposed. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT009317568 http://hdl.handle.net/11536/78780 |
显示于类别: | Thesis |
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