WO2004066162A2 - Calculation of a modified discrete cosine transform - Google Patents
Calculation of a modified discrete cosine transform Download PDFInfo
- Publication number
- WO2004066162A2 WO2004066162A2 PCT/EP2003/014930 EP0314930W WO2004066162A2 WO 2004066162 A2 WO2004066162 A2 WO 2004066162A2 EP 0314930 W EP0314930 W EP 0314930W WO 2004066162 A2 WO2004066162 A2 WO 2004066162A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- cosine
- input signal
- values
- length
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
- G06F17/147—Discrete orthonormal transforms, e.g. discrete cosine transform, discrete sine transform, and variations therefrom, e.g. modified discrete cosine transform, integer transforms approximating the discrete cosine transform
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
Definitions
- the invention relates to digital signal processing, and more particularly to the computation of an MDCT.
- the MDCT can be calculated either directly in a double loop or using an FFT. Since the latter involves transformation of a signal length that is the double of the original length N, and some data copying, the former is - dependent on the processor used - faster for shorter MDCT block lengths. Especially the MDCT of MPEG 1/2 Layer III has a length of
- a problem to be solved by the invention is performing an MDCT that requires a reduced amount of computing power and memory. This problem is solved by the method disclosed in claim 1.
- a corresponding computer program product implementing such method is disclosed in claim 5.
- An electronic cir- cuit that utilises this method is disclosed in claim 6, and a corresponding codec is disclosed in claim 10.
- the invention facilitates reducing the number of multiplications and additions in the loop of the direct calculation of the MDCT by a factor of 2', for the expense of N/2 additional additions, with N being the length of a processing or transform block for sample values of the input signal.
- the invention enables to calculate an MDCT by performing only N ⁇ /4 multiplications for transforming a digital input signal of length N. This is accomplished by first generating an intermediate signal based on the input signal . For the generation of the intermediate signal, additions and sub- tractions only are required, which are far less computationally expensive than multiplications.
- a cosine table is used for calculating the MDCT.
- the cosine table requires a number of N 2 /2 cosine values only such that a relatively small memory can be used for the implementation of the invention.
- the invention is particularly advantageous for audio and/or video codecs, such as MPEG 1/2 layer III, ATRAC, AAC and others .
- the invention enables to construct an audio and/or video consumer device, such as an MPEG player or a DVD player, with reduced processing power and memory requirements .
- the inventive method is suited for performing a modified discrete cosine transform of a digital input signal of length N, the method including the steps of: generating an intermediate signal of length N/2 based on said input signal; performing a number of N 2 /4 multiplications of data values of the intermediate signal with cosine values to generate an transformed output signal .
- the inventive electronic circuit performs a modified discrete cosine transform of a digital input signal of length N, the electronic circuit including: a cosine table having a number of N 2 /4 cosine values; - means for generating an intermediate signal of length N/2 based on said input signal, and for multiplication of the data values of said intermediate signal so as to generate a modified discrete cosine transformed output signal.
- FIG. 2 block diagram of a preferred implementation of an electronic circuit in accordance with the invention.
- a digital input signal is provided in step 100.
- the digital input signal has a block length of N, i.e. the digital input signal in each case has a number of N data values .
- an intermediate signal is calculated in step 102.
- the intermediate signal has a length of N/2.
- an MDCT is calculated based on the intermediate signal that has been determined in step 102.
- the intermediate signal has a length of N/2, a number of N 2 /4 multiplications are required to calculate the MDCT on the basis of the intermediate signal.
- the MDCT transformed signal is output for further processing.
- Fig. 2 shows a simplified block diagram of an electronic circuit 200 receiving the input signal x.
- This circuit can be implemented on a single chip. It has a processing unit 202, a program memory 204 and a memory 206 for storing a cosine table 208.
- Program code for performing 'the calculation of the intermediate signal (cf. step 102 of Fig. 1) and for calculating the MDCT (cf. step 104 of Fig. 1) is stored in the program memory 204.
- Cosine table 208 has a number of N 2 /2 cosine value entries which are used by the processing unit 202 when the program code of program memory 208 is executed in order to perform the required multiplications with the cosine values to obtain the MDCT transformed output signal y.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Computational Mathematics (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- Data Mining & Analysis (AREA)
- Algebra (AREA)
- Software Systems (AREA)
- General Engineering & Computer Science (AREA)
- Databases & Information Systems (AREA)
- Discrete Mathematics (AREA)
- Complex Calculations (AREA)
- Compression, Expansion, Code Conversion, And Decoders (AREA)
- Compression Or Coding Systems Of Tv Signals (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/542,481 US20060036666A1 (en) | 2003-01-18 | 2003-12-29 | Method, circuit, codec and computer program product for performing a modified discrete cosine transform |
JP2004566818A JP2006513496A (en) | 2003-01-18 | 2003-12-29 | Method, circuit, codec and computer program product for performing modified discrete cosine transform |
EP03808289A EP1584046A2 (en) | 2003-01-18 | 2003-12-29 | Calculation of a modified discrete cosine transform |
BR0317988-5A BR0317988A (en) | 2003-01-18 | 2003-12-29 | Computer program method, circuit, codec, and product for effecting modified discrete cosine transform |
AU2003303770A AU2003303770A1 (en) | 2003-01-18 | 2003-12-29 | Calculation of a modified discrete cosine transform |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP03090016.1 | 2003-01-18 | ||
EP03090016A EP1445706A1 (en) | 2003-01-18 | 2003-01-18 | Method, apparatus, and computer program for performing a modified discrete cosine transform |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2004066162A2 true WO2004066162A2 (en) | 2004-08-05 |
WO2004066162A3 WO2004066162A3 (en) | 2005-01-13 |
Family
ID=32605379
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2003/014930 WO2004066162A2 (en) | 2003-01-18 | 2003-12-29 | Calculation of a modified discrete cosine transform |
Country Status (8)
Country | Link |
---|---|
US (1) | US20060036666A1 (en) |
EP (2) | EP1445706A1 (en) |
JP (1) | JP2006513496A (en) |
KR (1) | KR20050100620A (en) |
CN (1) | CN100429645C (en) |
AU (1) | AU2003303770A1 (en) |
BR (1) | BR0317988A (en) |
WO (1) | WO2004066162A2 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5646960A (en) * | 1992-09-28 | 1997-07-08 | Sony Corporation | Inverse modified discrete cosine transform signal transforming system |
US20020106020A1 (en) * | 2000-02-09 | 2002-08-08 | Cheng T. C. | Fast method for the forward and inverse MDCT in audio coding |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL8601183A (en) * | 1986-05-12 | 1987-12-01 | Philips Nv | DISCRETE COSINUS TRANSFORMATION DEVICE. |
JP3349421B2 (en) * | 1998-01-30 | 2002-11-25 | 三洋電機株式会社 | Audio data compression / decompression device and digital filter |
US6721708B1 (en) * | 1999-12-22 | 2004-04-13 | Hitachi America, Ltd. | Power saving apparatus and method for AC-3 codec by reducing operations |
US7035332B2 (en) * | 2001-07-31 | 2006-04-25 | Wis Technologies, Inc. | DCT/IDCT with minimum multiplication |
-
2003
- 2003-01-18 EP EP03090016A patent/EP1445706A1/en not_active Withdrawn
- 2003-12-29 KR KR1020057013178A patent/KR20050100620A/en not_active Application Discontinuation
- 2003-12-29 WO PCT/EP2003/014930 patent/WO2004066162A2/en active Application Filing
- 2003-12-29 BR BR0317988-5A patent/BR0317988A/en not_active IP Right Cessation
- 2003-12-29 US US10/542,481 patent/US20060036666A1/en not_active Abandoned
- 2003-12-29 CN CNB200380108939XA patent/CN100429645C/en not_active Expired - Fee Related
- 2003-12-29 JP JP2004566818A patent/JP2006513496A/en active Pending
- 2003-12-29 AU AU2003303770A patent/AU2003303770A1/en not_active Abandoned
- 2003-12-29 EP EP03808289A patent/EP1584046A2/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5646960A (en) * | 1992-09-28 | 1997-07-08 | Sony Corporation | Inverse modified discrete cosine transform signal transforming system |
US20020106020A1 (en) * | 2000-02-09 | 2002-08-08 | Cheng T. C. | Fast method for the forward and inverse MDCT in audio coding |
Also Published As
Publication number | Publication date |
---|---|
EP1445706A1 (en) | 2004-08-11 |
CN100429645C (en) | 2008-10-29 |
CN1739104A (en) | 2006-02-22 |
AU2003303770A1 (en) | 2004-08-13 |
AU2003303770A8 (en) | 2004-08-13 |
BR0317988A (en) | 2005-12-06 |
KR20050100620A (en) | 2005-10-19 |
JP2006513496A (en) | 2006-04-20 |
US20060036666A1 (en) | 2006-02-16 |
EP1584046A2 (en) | 2005-10-12 |
WO2004066162A3 (en) | 2005-01-13 |
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