Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Review Article An Overview of the Coding Standard MPEG-4 Audio Amendments 1 and 2: HE-AAC, SSC, and HE-AAC v2 | Hindawi Publishing Corporation EURASIP Journal on Audio Speech and Music Processing Volume 2009 Article ID 468971 21 pages doi 2009 468971 Review Article An Overview of the Coding Standard MPEG-4 Audio Amendments 1 and 2 HE-AAC SSC and HE-AAC v2 A. C. den Brinker 1 J. Breebaart 1 P. Ekstrand 2 J. Engdegard 2 F. Henn 2 K. Kjorling 2 W. Oomen 3 and H. Purnhagen2 1 Philips Research Laboratories High Tech Campus 36 5656 AE Eindhoven The Netherlands 2Dolby Sweden AB Gavlegatan 12 A 11330 Stockholm Sweden 3Philips Applied Technologies Eindhoven High Tech Campus 5 5656 AE Eindhoven The Netherlands Correspondence should be addressed to A. C. den Brinker Received 29 September 2008 Accepted 24 February 2009 Recommended by James Kates In 2003 and 2004 the ISO IEC MPEG standardization committee added two amendments to their MPEG-4 audio coding standard. These amendments concern parametric coding techniques and encompass Spectral Band Replication SBR Sinusoidal Coding SSC and Parametric Stereo PS . In this paper we will give an overview of the basic ideas behind these techniques and references to more detailed information. Furthermore the results of listening tests as performed during the final stages of the MPEG-4 standardization process are presented in order to illustrate the performance of these techniques. Copyright 2009 A. C. den Brinker et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. Introduction The MPEG-2 Audio coding standard was released in 1997 and has successfully found its way into the market. Later MPEG-4 Audio Version 1 and Version 2 were issued in mid 1999 and early 2000 respectively. These versions have adopted the MPEG-2 AAC coder including several extensions to it. In addition several other components like speech coders HVXC and CELP and a .