Synthesis subband filter in MPEG-II audio decoding

Details Synthesis subband filter in MPEG-II audio decoding Synthesis subband filter in MPEG-II audio decoding

1998-08-03

2001-03-06

Dorvil, Richemond (Department: 2641)

Data processing: speech signal processing, linguistics, language

Speech signal processing

For storage or transmission

C704S201000, C704S236000, C704S258000, C704S269000, C704S268000

Reexamination Certificate

active

06199039

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an MPEG-II audio decoder, and in particular to the synthesis subband filter in the MPEG-II audio decoder.
BACKGROUND OF THE INVENTION
The ISO MPEG-II audio standard has developed a world-wide standard audio coding algorithm, which can significantly reduce the requirements of transmission bandwidth and data storage with low distortion. With the recent advances in VLSI and ATM networking technology, the low-cost MPEG-II audio decoder in real-time system becomes more essential for multimedia applications.
The MPEG-II audio coding standard is an extension of MPEG-I. Emphasis of the new activity is on multichannel and multilingual audio and on an extension of the existing standard to lower sampling frequencies and lower bit rates. In addition, backward compatibility is a key aspect to ensure the existing two channel decoders will still be able to decode compatible stereo information from five multichannel signals. This implies the provision of compatibility matrices, using adequate inverse matrix coefficients.
The MPEG-II decoding flow chart is shown in FIG.
1
. Also, within the synthesis subband filter, the inverse Modified Discrete Cosine Transform (IMDCT) V
i
of a sequence S
k
(where N
i
is the cosine function defined in equation (1), below), and the inverse Pseudo Quadrature Mirror Filter (IPQMF) U
ij
(defined as a function of IMDCT V
i
, where D
i
is a standard windowing coefficient as defined the MPEG standard ISO CO 11172-3) will be realized, as shown in FIG.
2
. The IMDCT module makes the perfect reconstruction feasible as a polyphase QMF transform kernel. The IPQMF module can be further decomposed into four functions, such as: shifting, rearranging, windowing and partial summation. According to the computation power analysis for MPEG-II audio decoding in Table 1, the computation load synthesis subband filter illustrated in
FIG. 2
depends to a great extent on the realization of IMDCT module, while the IPQMF also induces substantial computation and some data arrangement. Moreover, the inverse quantization (IQ) and multichannel (MC) modules although occupying little of the computational load of the whole process, present some data access and arrangement issues which make the decoding flow more uncompact.
TABLE 1
Classification
Function
MOPS
1)
IQ
Degrouping
0.88
Requantization
1.44
Rescalzation
0.96
3.28
MC
Dematrixing
0.576
Denormalization
1.44
2.016
Synthesis
IMDCT
61.44
Subband Filter
IPQMF
19.22
81.36
Total
86.656
1)
MOPS: Million Operations per Second
SUMMARY OF THE INVENTION
In the present invention, we present a novel MPEG-II audio decoder, which is capable of decoding MPEG-II standard multichannel audio bitstreams for Layer I and II. This invention is also intended to show an efficient data arrangement and memory configuration for low complexity and low cost applications.


REFERENCES:
Tsung-Han Tsai, Liang-Gee Chen and Yuan-Chen Liu, “A Novel MPEG-2 Audio Decoder with Efficient Data Arrangement and Memory Configuration” Jun. 1997.
Tsung-Han Tsai, Thou-Ho Chen and Liang-Gee Chen, “An MPEG Audio Decoder Chip”, IEEE Nov. 1995.
Tsung-Han Tsai, Thou-Ho Chen and Liang-Gee Chen, Design and VLSI Implementation of MPEG Audio Decoder, Jun. 1995.
Tsung-Han Tsai, Liang-Gee Chen and Ruei-Xi Chen, “Implementation Strategy of MPEG-II Audio Decoder and Efficient Multichannel Architecture”, IEEE Nov. 1997.

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