A new approach for channel equalization without guard interval using polyphase matrices. - In: PIMRC 2005, ISBN 978-3-8007-2909-8, (2005), insges. 5 S.
A comparison of integer fast Fourier transforms for lossless coding. - In: IEEE International Symposium on Communications and Information Technology, 2004, (2004), S. 1069-1073
The lifting scheme-based integer fast Fourier transform (IntFFT), an integer approximation of the FFT, is reversible. When it is used for lossless coding applications, the computational complexity and approximation error increase due to realization of the trivial butterflies by three lifting steps. Since the error appears as a "noise floor" and it limits the lossless coding efficiency, it is desirable to reduce not only the computational complexity but also the noise floor level as much as possible. This survey presents two schemes to realize an improved IntFFT in terms of the number of arithmetic operations and the level of the noise floor. The first scheme is based on employment of two/three lifting step schemes with combined rounding operations, and the second one is the multidimensional lifting (MDL) scheme. The improvement is shown by comparing the number of arithmetic operations and rounding operations to compute the IntFFT and also by comparing levels of the noise floor. In addition, an improvement in lossless coding efficiency due to the reduced noise floor can be predicted by observing the reduced estimated entropy of the IntFFT coefficients.
https://doi.org/10.1109/ISCIT.2004.1413884
Approximation error analysis for transform-based lossless audio coding. - In: IEEE Global Telecommunications Conference workshops, 2004, GlobeCom workshops 2004, (2004), S. 595-599
The integer modified discrete cosine transform (IntMDCT), an integer approximation of the MDCT, is a reversible transform realized by the lifting scheme and thus is a useful transform for lossless audio coding. Because of the integer approximation, however, the approximation error appears as a "noise floor" in the transform domain and limits the lossless coding efficiency. In this paper, a theoretical analysis of the approximation error of the IntMDCT is discussed. The result is then used to design a simple test filter applied to each rounding operation of the IntMDCT in such a way that the error spectrum is shaped towards the low frequencies. As a result, especially when the spectral energy of an input signal is concentrated in the low frequency domain, the lossless coding efficiency is improved.
https://doi.org/10.1109/GLOCOM.2004.1378032
Improved integer transforms using multi-dimensional lifting. - In: 2004 IEEE International Conference on Acoustics, Speech, and Signal Processing, (2004), S. II-1005-II-1008
Recently lifting-based integer transforms have received much attention, especially in the area of lossless audio and image coding. The usual approach is to apply the lifting scheme to each Givens rotation. Especially in the case of long transform sizes in audio coding applications, this leads to a considerable approximation error in the frequency domain. This paper presents a multidimensional lifting approach for reducing this approximation error. In this approach, large parts of the transform are calculated without rounding operations, only the output is rounded and added. The new approach is applied and evaluated for both the integer modified discrete cosine transform (IntMDCT) and the integer fast Fourier transform (IntFFT).
https://doi.org/10.1109/ICASSP.2004.1326430
Improved lossless audio coding using the noise-shaped IntMDCT. - In: 2004 IEEE 11th Digital Signal Processing Workshop, 2004 and the 3rd IEEE Signal Processing Education Workshop, (2004), S. 356-360
This paper discusses approximation noise shaping to improve the efficiency of the integer modified discrete cosine transform (IntMDCT)-based lossless audio codec. The scheme is applied to rounding operations associated with lifting steps to shape the noise spectrum towards the low frequency bands. In this paper, constraints on the noise shaping filter and a design procedure with the constraints are discussed. Several noise shaping filters are designed and experimental results showing the improvement are presented.
https://doi.org/10.1109/DSPWS.2004.1437975
A guideline to audio codec delay. - In: Full set of convention papers presented at the 116th AES convention, (2004), Paper 6062
Ultra low delay audio coding with constant bit rate. - In: Convention papers, 117th convention, (2004), Paper 6197
Improved integer transforms for lossless audio coding. - In: Conference record of the Thirty-Seventh Asilomar Conference on Signals, Systems & Computers, (2003), S. 2119-2123
Lifting scheme based integer transforms are very powerful tools to construct lossless coding schemes. These transforms such as the integer fast fourier transform (IntFFT) and the integer modified discrete cosine transform (IntMDCT) are integer approximations of the original floatingpoint transforms, and hence there is an approximation error in the transform domain. This paper will propose structures for improved integer transforms in terms of improved approximation accuracy and computational efficiency. Experimental results will show that clear improvements in these two points are achieved in lossless audio coding.
https://doi.org/10.1109/ACSSC.2003.1292354
Fine grain scalable perceptual and lossless audio coding based on IntMDCT. - In: 2003 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics proceedings, (2003), S. 50
D-08
The paper presents an embedded fine grain audio coding scheme. The enabling technology for this combined perceptual and lossless audio coding approach is the integer modified discrete cosine transform (IntMDCT), which is an integer approximation of the MDCT based on the lifting scheme. It maintains the perfect reconstruction property and therefore enables efficient lossless coding in the frequency domain. The close approximation of the MDCT also allows a perceptual coding scheme to be built based on the IntMDCT. A bitsliced arithmetic coding technique is applied to the IntMDCT values. Together with the encoded shape of the masking threshold, a perceptually hierarchical bitstream is obtained, containing several stages of perceptual quality and extending to lossless operation when transmitted completely. A concept of encoding subslices is presented in order to obtain a fine adaptation to the masking threshold, especially in the range of perceptually transparent quality.
https://doi.org/10.1109/ASPAA.2003.1285813
Fine grain scalable perceptual and lossless audio coding based on IntMDCT. - In: 2003 IEEE International Conference on Acoustics, Speech, and Signal Processing, (2003), S. V-445-V-448
This papers presents an embedded fine grain scalable perceptual and lossless audio coding scheme. The enabling technology for this combined perceptual and lossless audio coding approach is the integer modified discrete cosine transform (IntMDCT), which is an integer approximation of the MDCT based on the lifting scheme. It maintains the perfect reconstruction property and therefore enables efficient lossless coding in the frequency domain. The close approximation of the MDCT also allows us to build a perceptual coding scheme based on the IntMDCT. In this paper a bitsliced arithmetic coding technique is applied to the IntMDCT values. Together with the encoded shape of the masking threshold a perceptually hierarchical bitstream is obtained, containing several stages of perceptual quality and extending to lossless operation when transmitted completely. A concept of encoding subslices is presented in order to obtain a fine adaptation to the masking threshold especially in the range of perceptually transparent quality.
https://doi.org/10.1109/ICASSP.2003.1200002