• Proceedings of the KAIS Fall Conference
• /
• 2010.05a
• /
• pp.269-272
• /
• 2010

In this paper, we propose the computation reduction methods of delta pitch search that is used in G.723.1 vocoder. In order to decrease the computational amount in delta pitch search the characteristic of proposed algorithms is as the following. First, scheme to reduce the computation amount in delta pitch search uses NAMDF. Developed the second scheme is the skipping technique of lags in pitch searching by using the threshold value. By doing so, we can reduce the computational amount of pitch searching more than 64% with negligible quality degradation.

• Speech Sciences
• /
• v.11 no.3
• /
• pp.165-172
• /
• 2004

In this paper, we propose the computational complexity reduction methods of delta pitch search that is used in G.723.1 vocoder. In order to decrease the computational complexity in delta pitch search the characteristic of proposed algorithms is as the following. First, scheme to reduce the computational complexity in delta pitch search uses NAMDF. Developed the second scheme is the skipping technique of lags in pitch searching by using the threshold value. By doing so, we can reduce the computational amount of pitch searching more than 64% with negligible quality degradation.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1994.06c
• /
• pp.214-217
• /
• 1994

The major drawback in the Code Excited Linear Prediction type vocoders is their large computational requirements. In this paper, a simple method is proposed to reduce the pitch searching time in the pitch filter almost without degradation of quality. On the basis of the observational regularity of the correlation function of speech, only the limited numbers of pitch lags are considered to be an optimum pitch. This is done by skipping the negative envelope side of the correlation function and limiting the maximum number of lags to be considered preliminarily. By doing so, we can reduce the computational time of pitch searching more than 51% with negligible quality degradation. In addition to that, by combining that method with the conventional delta search technique, we can reduce the computational time requirements more than 60% without serious lowering the speech quality in segmental SNR measure compared to the conventional full search method.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.119-122
• /
• 2004

G.723.1은 저 전송률 환경에서 고 음질을 제공하여 주고 있으나 CELP형 부호화기가 갖는 합성에 의한 분석(Analysis by Synthesis)방식의 구조로 인해 많은 처리 시간과 계산량을 요구하게 된다. 본 논문에서는 G.723.1에 대해 NAMDF함수를 적용하여 델타 피치 검색과정의 계산량을 줄여 부호화기의 전체 계산량을 감소시키는 방법을 제안하였다. 기존의 피치 검출 알고리즘에서 피치 검출을 위해 사용하고 있는 자기상관함수는 곱셈 연산에서 발생하는 bit의 dynamic range가 커서 나눗셈 연산에서도 과도한 연산량을 필요로 한다. 따라서, 이러한 계산량의 감소를 위해 기존의 자기상관함수 대신 계산량을 감소하기 위하여 NAMDF 방법을 적용하였고 추가된 skipping 기법을 사용하였다. 계산량 감소율 측면에서는 약 $64\%$의 감소율을 보였고 기존의 방법과 제안한 방법간의 피치 pitch contour은 원음성의 피치 contour와 유사하였고, 음질 평가에서도 기존의 G.723.1 부호화기 합성음과 유사한 길과를 얻을 수 있었다.