• Title/Summary/Keyword: TDAC

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Enhanced Spectral Envelope Coding Scheme Using Inter-frame Correlation for G.729.1 (G.729.1 코더에서 프레임 간의 상호상관 관계를 이용한 개선된 스펙트럼 포락 코딩 방법)

  • Cho, Keun-Seok;Sung, Jong-Mo;Hahn, Min-Soo;Kim, Young-Il;Jeong, Sang-Bae
    • Phonetics and Speech Sciences
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    • v.1 no.4
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    • pp.97-103
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    • 2009
  • This paper describes a new algorithm for encoding spectral envelope in the time domain alias cancellation (TDAC) part of G.729.1. The spectral envelope and modified discrete cosine transform (MDCT) coefficients of the weighted code-excited linear predictive (CELP) coding error in lower-band and the higher-band input signal are encoded in the TDAC part. In order to reduce allocation bits for spectral envelope coding, a new algorithm using sub-band correlation between adjacent frames is proposed. In addition, to improve the quality of decoded signals, two bit allocation strategies using reduced bits from the proposed algorithm are proposed. The performance of the proposed algorithm is evaluated in terms of objective quality and bit reduction rates. Experimental results show that the proposed algorithm increases the quality of sounds significantly.

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Fixed-point Error Optimization of AC-3 Decoding Algorithm (AC-3 복호화 알고리듬의 고정 소수점 오차 최적화)

  • 이근섭
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1998.08a
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    • pp.438-441
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    • 1998
  • 최근 미국 내 표준안으로서 많이 사용되고 있는 AC-3 오디오 알고리듬은 그 복잡성으로 인하여 실시간 구현을 위해선 프로세서로 구현하는 것이 적합하다. AC-3 복호화 알고리듬은 많은 부분이 실수연산으로 이루어져 있으므로 소수점을 고려한 연산이 필요한데, 프로세서로 구현할 때는 적은 비용과 빠른 속도로 실수연산을 수행하기 위해서 부동소수점보다는 고정소수점 연산이 유리하다. 그러나 고정소수점 연산시 발생하는 유한 단어길이 효과로 인하여 양자화 오차가 발생하므로 복호화된 오디오 신호의 음질저하를 최소화하기 위해서는 최적화가 필요하다. 본 논문에서는 AC-3 복호화 알고리듬의 부분별 양자화 오차를 분석하고 그 결과 가장 많은 오차를 발생시키는 역 TDAC 변환의 오차를 최적화하였다. Fast TDAC 변환이 FFT로 이루어져 있으므로 고정 소수점 연산시 오차가 적은 FFT 구조를 제안하였다. 제안된 구조를 사용하여 AC-3 고정소수점 복호화기를 C 언어를 사용하여 구현하였으며, AC-3 부동소수점 복호화기와 최종 PCM을 비교하여 그 성능을 평가하였다.

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Improved Time Domain Aliasing Cancellation Filter Bank Based on the Multiple Overlap-add Structure (다중 중첩-합 구조에 기반한 개선된 시간 영역 엘리어싱 제거 필터 뱅크)

  • 유철재;김형명
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.8B
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    • pp.1057-1069
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    • 2001
  • 오디오 부호화 시스템에 널리 쓰이는 시간 영역 엘리어싱 제거(TDAC) 필터 뱅크의 성능 개선을 위하여, 다중 중첩-합 구조를 바탕으로 한 개선된 TDAC 필터 뱅크를 제안하였다. 제안된 구조는 필터 뱅크의 분해 부분과 합성 부분 사이에서 발생하는 양자화 잡음의 효과를 줄이도록 제안되었다. 모의 실험을 통해 같은 양자화 비트 수를 사용하는 경우에 제안한 시스템이 SNR 측면에서 보다 나은 성능을 나타냄을 보였으며, 망 전송 데이터 양을 같게 한 경우에도 제안한 시스템이 더 적은 데이터 양의 블록 단위를 가질 수 있으므로 데이터 망의 혼잡 제어에 있어 보다 유리할 수 있음을 보였다.

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A Design on the Vector-Processor of 2048 Point MDCT/IMDCT for Digital Audio (디지털 오디오를 위한 2048포인트 MDCT/IMDCT 벡터프로세서 설계)

  • Gu, Dae Seong;Jeong, Yang Gwon;Kim, Jong Bin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.9C
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    • pp.851-859
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    • 2003
  • 최근 사용자들의 멀티채널 선호도는 급속도로 전파되고 있다. MPEG은 동영상 및 음향시스템의 데이터 압축기술을 제공하는데, 현재 각광을 받고있는 것이 디지털 오디오이다. MPEG 표준안은 MPEG-1오디오 알고리즘을 MPEG-2 알고리즘에 동일하게 사용해도 멀티채널 및 5.1채널 사운드륵 제공한다. MDCT(Modified Discrete Cosine Transform)는 TDAC(Time Domain Aliasing Cancellation)에 기반을 두고있는 변형이산 여현 변환을 나타낸 것이다. 본 논문에서는 오디오 부분의 핵심이라 할 수 있는 MDCT/IMDCT(Inverse MDCT) 알고리즘을 최적화하여 효율적인 알고리즘을 제안하였다. 그리고 연산과정에서 중복되는 영역을 묶음으로써 연산에 필요한 계수를 줄였다. 최적화 전에 비해 코사인 계수를 0.5%이하로 최적화하였고, 승산에서 0.098%, 가산에서 0.58% 효율을 보였다. 알고리즘 검증은 C언어를 사용하여 검증하였고, 최적화된 알고리즘을 적용하여 마이크로 프로그램 방식의 하드웨어 구조론 설계하였다.

Low delay window switching modified discrete cosine transform for speech and audio coder (음성 및 오디오 부호화기를 위한 저지연 윈도우 스위칭 modified discrete cosine transform)

  • Kim, Young-Joon;Lee, In-Sung
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.2
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    • pp.110-117
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    • 2018
  • In this paper, we propose a low delay window switching MDCT (Modified Discrete Cosine Transform) method for speech/audio coder. The window switching algorithm is used to reduce the degradation of sound quality in non-stationary trasient duration and to reduce the algorithm delay by using the low delay TDAC (Time Domain Aliasing Cancellation). While the conventional window switching algorithms uses overlap-add with different lengths, the proposed method uses the fixed overlap add length. It results the reduction of algorithm delay by half and 1 bit reduction in frame indication information by using 2 window types. We apply the proposed algorithm to G.729.1 based on MDCT in order to evaluate the performance. The propose method shows the reduction of algorithm delay by half while speech quality of the proposed method maintains same as the conventional method.

Protective effect of Korean diet food groups on lymphocyte DNA damage and contribution of each food group to total dietary antioxidant capacity (TDAC) (한식 식품군의 in vitro 총 항산화능 (TDAC)과 ex vivo DNA 손상 보호효과와의 관련성)

  • Lee, Min Young;Han, Jeong-Hwa;Kang, Myung-Hee
    • Journal of Nutrition and Health
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    • v.49 no.5
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    • pp.277-287
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    • 2016
  • Purpose: This study was performed to compare total phenolic contents, in vitro antioxidant capacity, and reduction effect of Korean food groups on ex vivo DNA damage in human cells and analyze correlations between each indicator. Methods: Vegetable foods in the Korean diet based the results of the KNHANES V-2 (2011) were classified into 10 food groups: cereals, fruits, vegetables, nuts, kimchi, seaweeds, potatoes, mushrooms, legumes, and oils. Eighty-four foods constituted more than 1% of the total intake in each food group and finally designated as vegetable foods in the Korean diet. Total phenolic content of each food group was measured. Further, in vitro antioxidant capacity was measured based on DPPH radical scavenging assay, TEAC assay, and $ORAC_{ROO{\cdot}}$ assay. Ex vivo DNA damage in human lymphocytes was assessed using comet assay. Results: Total phenolic contents of food groups of the Korean diet increased in the order of mushrooms, fruits, vegetables, seaweeds, and kimchi. Meanwhile, antioxidant rankings of food groups as mean values from the three in vitro test methods increased in the order of mushrooms, seaweeds, vegetables, kimchi, and fruits. Protection against ex vivo DNA damage in human lymphocytes was highest in mushrooms, followed by vegetables, fruits, seaweeds, and kimchi. The rankings of the food groups for total phenolic content, in vitro DAC, and ex vivo DNA protection activity were similar, and correlations between each indicator were significantly high. Conclusion: Mushrooms, fruits, vegetables, and seaweeds among the tested food groups in the Korean diet showed high total phenolic contents, in vitro antioxidant capacities, and protection against DNA damage. Correlations between each indicator in terms of total phenolic content, in vitro antioxidant capacity, and ex vivo DNA protection between each food group were found to be particularly high.

Implementation of MDCT core in Digital-Audio with Micro-program type vector processor

  • Ku Dae Sung;Choi Hyun Yong;Ra Kyung Tae;Hwang Jung Yeun;Kim Jong Bin
    • Proceedings of the IEEK Conference
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    • 2004.08c
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    • pp.477-481
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    • 2004
  • High Quality CD, OAT audio requires that large amount of data. Currently, multi channel preference has been rapidly propagated among latest users. The MPEG(Moving Picture Expert Group) is provides data compression technology of sound and image system. The MPEG standard provides multi channel and 5.1 sounds, using the same audio algorithm as MPEG-l. And MPEG-2 audio is forward and backward compatible. The MDCT (Modified Discrete Cosine Transform) is a linear orthogonal lapped transform based on the idea of TDAC(Time Domain Aliasing Cancellation). In this paper, we proposed the micro-program type vector processor architecture a benefit in MDCT/IMDCT of MPEG-II AAC. And it's reduced operating coefficient by overlapped area to bind. To compare original algorithm with optimized algorithm that cosine coefficient reduced $0.5\%$multiply operating $0.098\%$ and add operating 80.58\%$. Algorithm test is used C-language then we designed hardware architecture of micro-programmed method that applied to optimized algorithm. This processor is 20MHz operation 5V.

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Fixed-point Optimization of a Multi-channel Digital Hearing Aid Algorithm (다중 채널 디지털 보청기 알고리즘의 고정 소수점 연산 최적화)

  • Lee, Keun Sang;Baek, Yong Hyun;Park, Young Chul
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.2 no.2
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    • pp.37-43
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    • 2009
  • In this study, multi-channel digital hearing aid algorithm for low power system is proposed. First, MDCT(Modified Discrete Cosine Transform) method converts time domain of input speech signal into frequency domain of it. Output signal from MDCT makes a group about each channel, and then each channel signal adjusts a gain using LCF(Loudness Compensation Function) table depending on hearing loss of an auditory person. Finally, compensation signal is composed by TDAC and IMDCT. Its all of process make progress 16-bit fixed-point operation. We use fast-MDCT instead of MDCT for reducing system complexity and previously computed tables instead of log computation for estimating a gain. This algorithm evaluate through computer simulation.

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Implementation of filterbank for MPEG-2 AAC decoder with VHDL (VHDL을 이용한 MPEG-2 AAC 복호화기 필터뱅크의 구현)

  • 우광희;차형태
    • Proceedings of the IEEK Conference
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    • 2000.06d
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    • pp.178-181
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    • 2000
  • In this paper, we present the implementation of filterbank for MPEG-2 Advanced Audio Coding (AAC) decoder with VHDL. The filterbank of AAC employs a technique called time-domain aliasing cancellation (TDAC). In order to make the algorithm more efficiently, we decompose and reorganize the filterbank algorithm lot the high speed decoding process and lower computational cost. And we make this filterbank algorithm to be used with other modules of AAC decoder in parallel processing.

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A Study on the Dynamic Window Switching MDCT for Enhanced AC-3 Audio Filterbank (다이나믹 윈도우 스위칭기법을 적용한 AC-3 오디오 필터뱅크의 성능향상에 관한 연구)

  • 김준성
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1998.06e
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    • pp.23-26
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    • 1998
  • This paper presents a technique to enhance TDAC in the AC-3 algorithm. To reduce block boundary noise without decreasing the performance of transform coding, new special window adopted. They improves the defect of the AC-3 algorithm that could not properly cancel aliasing in the tansient period. In addition, a fast MDCT calculation algorithm based on a fast Fourier Transform, is adopted.

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