Additive sinusoidal synthesis is a popular technique for applications like sound synthesis or very low bit rate parametric audio decoding. In this paper, different algorithms for the efficient synthesis of sinusoids on general purpose CPUs as found in today’s PCs are investigated. Fast algorithms for time domain synthesis of constant and linearly changing frequencies are presented and compared to frequency domain synthesis approaches. Execution time and accuracy (SNR) of the algorithms are reported for different CPU types. Finally, the algorithms are implemented in a fast MPEG-4 HILN parametric audio decoder in order to evaluate their performance in a real world application.

Download

Parametric stereo coding in combination with a State-of-the-Art coder for the underlying monaural audio signal results in the most ef cient coding scheme for stereo signals at very low bit rates available today. This paper reviews those aspects of the parametric stereo paradigm that are important for audio coding applications. A complete parametric stereo coding system is presented, which was recently standardized in MPEG-4 Audio. Using complex modulated lter banks, it allows implementation with low computational complexity. The system is backward compatible and enables high quality stereo coding at total bit rate of 24 kbit/s when used in combination with aacPlus.

Download