| High quality and low bit-rate has been the targets of both speech coding and audio coding. Speech coding offers very low bit-rate, but it focuses on narrow band speech signals. On the other hand, audio coding provides excellent quality, but it is hard to improve compression ratio. Therefore, both of them are searching for novel technology to help them realize the targets.Spectral band extension (SBE) technology is a good solution for the targets mentioned above. This paper reviews some algorithms of spectral band extension technology, including both non-blinding and blinding extensions, and spectral band replication (SBR). One of the most popular methods of spectral band extension is thoroughly studded. Firstly in the thesis, some key technologies related to SBE are described, a set of algorithms about SBR in EAAC+ software are studded. Secondly, based on tests and evaluations of the algorithms, some of the deficiencies of the SBR processing are addressed. Then some new strategies, methods and algorithms of the SBE technology, which will overcome the drawbacks, are designed and tested.The performances of the innovation schemes have shown some improvements and advantages for spectral band extensions. Even they are not always good in any cases, but still have some potential feathers, so further study and investigations about these issues are expected. |
