Modified discrete cosine transform

About: Modified discrete cosine transform is a research topic. Over the lifetime, 1453 publications have been published within this topic receiving 30211 citations. The topic is also known as: Modified Discrete Cosine Transform, MDCT.

Efficient MDCT Recursive Structure for VLSI Implementation

Abstract: Modified discrete cosine transform (MDCT) is a computationally intensive fundamental processing block for mapping time into frequency in various versions of MPEG audio coding. An efficient algorithm for MDCT computation is a basic requirement to realize low-cost audio codec. This paper introduces a new recursive algorithm and architecture for MDCT. The proposed architecture requires minimum hardware and execution time. Folding of the input sequence is performed multiple times in the subsequent groups which results in a significant reduction in real multiplication and real addition operations. Also, fewer number of execution cycles are required to generate the output through this algorithm. The proposed structure is suitable for parallel VLSI implementation as it is simple, regular and modular.

Spectral shape estimation from mdct coefficients

Abstract: A method, decoder, and program code for controlling a concealment method for a lost audio frame is provided. A first audio frame and a second audio frame of the received audio signal are decoded to obtain modified discrete cosine transform (MDCT) coefficients. Values of a first spectral shape based upon the MDCT coefficients decoded from the first audio frame decoded and values of a second spectral shape based upon MDCT coefficients decoded from the second audio frame decoded are determined, the spectral shapes each comprising a number of sub-bands. The values of the spectral shapes and frame energies of the first audio frame and second audio frame are transformed into representations of FFT based spectral analyses. A transient condition is detected based on the representations of the FFTs. Responsive to detecting the transient condition, the concealment method is modified by selectively adjusting a spectrum magnitude of a substitution frame spectrum.

***WITHDRAWN PATENT AS PER THE LATEST USPTO WITHDRAWN LIST***Orthogonal transform apparatus, orthogonal transform method, orthogonal transform computer program, and audio decoding apparatus

Abstract: An orthogonal transform apparatus computes either one of the real and imaginary components of the quadrature mirror filter coefficient contained in a first subinterval of a plurality of subintervals among which a coefficient sequence containing a plurality of quadrature mirror filter coefficients is divided so that the values of basis functions are symmetrically placed, by computing a sum of products of the plurality of modified discrete cosine transform coefficients and the basis functions corresponding to the subinterval, computes the other one of the real and imaginary components of the quadrature mirror filter coefficient contained in the first subinterval and the real and imaginary components of the quadrature mirror filter coefficient contained in another subintervals by performing a butterfly operation using a computed value produced as a result of the sum of products and computes each quadrature mirror filter coefficient by combining the real component and imaginary component thereof.

Mdct - device method and computer program stored in computer-readable medium for voice conversion using change of mdct energy according to formant change

Abstract: The present invention relates to a device, a method, and a computer program stored in a computer-readable medium for voice conversion using a change of MDCT energy according to a formant change. According to an embodiment of the present invention, the device for voice conversion includes: a reception unit which receives a voice signal; a spectrum envelop extraction unit which extracts a fast Fourier transform spectrum envelope; a formant location transformation unit which seeks a modified fast Fourier transform spectrum envelope (M-FFT SP); a gain obtainment unit which obtains a gain; a modified discrete cosine transform coefficient (MDCT) energy transformation unit which seeks an energy modified MDCT coefficient (EM-MDCT CE) in a log MDCT spectrum; a restoration unit which restores the voice signal to a tone modified signal in a time area; and an amplitude adjusting unit which adjusts an amplitude of the tone modified signal.

An Improvement Method for Data Embedding to Printing Images Based on DCT

Abstract: This paper proposes an improvement method for a data embedding technique to printing images This embedding technique is based on discrete cosine transform (DCT) and pseudo number (PN) sequences In the conventional method, deformations, such as rotation and scaling have given a serious defect to the extraction rate To solve this problem, a new data embedding position and the processing by the resolution of scanner itself are applied The gain control method is also improved From the comparison between the proposed and conventional methods, the improvement of the extraction rate in the proposed method is shown