Transform and subband coding of audio signals

Background

Most of the current audio codecs decompose the input signal into spectral components. These spectral components can then be coded more efficiently than the full bandwidth input signal. The quantization is controlled by a psychoacoustic model so that the audibility of the resulting distortions is kept minimal. Subsequent entropy coding aims at a minimization of the resulting bit rate.

Goal

The individual components are to be optimized in order to increase the coding efficiency of the overall system.

Approach

Focus is given on the following topics:

• Optimization of filter banks and transforms
• Psychoacoustic models
• Quantization and coding

References

• O. Niemeyer, B. Edler, "Detection and Extraction of Transients for Audio Coding", 120th AES Convention, Paris, May 2006.
• W. Nogueira, A. Giese, B. Edler, A. Büchner, "Wavelet Packet Filterbank for Speech Processing Strategies in Cochlear Implants," IEEE International Conference on Acoustics, Speech, and Signal Processing, Toulouse, May 2006.
• N. Meine, B. Edler, "Improved Quantization and Lossless Coding for Subband Audio Coding," 118th AES Convention, Barcelona, May 2005.
• O. Niemeyer, B. Edler, "Efficient Coding of Excitation Patterns Combined with a Transform Audio Coder," 118th AES Convention, Barcelona, May 2005.
• W. Nogueira, A. Buechner, B. Edler, "Fundamental Frequency Coding in NofM Strategies for Cochlear Implants," 118th AES Convention, Barcelona, May 2005.
• G. Schuller, B. Edler, A. Doser, "A Method for Alias Reduction in Cascaded Filter Banks," 9th IEEE DSP Workshop, Hunt, TX, Oct. 2000.
• F. Baumgarte, B. Edler, "Ein Psychophysiologisches Gehörmodell zur Nachbildung von Wahrnehmungsschwellen für die Audiocodierung," DFG-Abschlußkolloquium, München, Okt. 2000.
• B. Edler, C. Faller, G. Schuller, "Perceptual Audio Coding Using a Time-Varying Linear Pre- and Post-Filter," 109th AES Convention, Los Angeles, Sep. 2000.
• B. Edler, G. Schuller, "Audio Coding Using a Psychoacoustic Pre- and Post-Filter," IEEE International Conference on Acoustics, Speech, and Signal Processing, Istanbul, June 2000.