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. 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 tonalities, 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 paper, 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.
Click to purchase paper as a non-member or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $33 for non-members and is free for AES members and E-Library subscribers.