EP0421444A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Pitch period searching method and circuit for speech code
Assignee: Fujitsu Ltd
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Filing: 1990-10-05
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Granted: —
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Expires: 2010-10-05
Abstract
Abstract Pitch periods for a long term predictor (16) included in a speech codec are searched in two searching stages. In the first searching stage, probable pitch periods are searched skipping a constant number of pitch periods, and in the second searching stage, pitch periods including the pitch period determined in the first searching stage and pitch periods neighboring the pitch period on both sides are searched.
Inventors
- 👤 Yoshinori Tanaka
- 👤 Tomohiko Taniguchi
- 👤 Akira Sasama
- 👤 Yasuji Ohta
- 👤 Fumio Amano
- 👤 Shigeyuki Unagami
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 05:01
CPC Classifications
G; G10; G10L; G10L25/00; G10L25/90
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
108 words
A pitch period searching method for searching pitch periods, which are probable in speech signals, for the most adequate pitch period for a long term predictor (16) included in a speech codec, characterized in that the method comprises the steps of: first searching the probable pitch periods skipping a first number (M) of pitch periods, to find the most adequate pitch period (D₁) among the searched pitch periods, and second searching a second number of pitch periods including said pitch period (D₁) and pitch periods neighboring said pitch period (D₁) on both sides, to find the most adequate pitch period (D₂) among the second number of pitch periods.
Claim 2
Dependent Claim
108 words
A pitch period searching method for searching pitch periods, which are probable in speech signals, for the most adequate pitch period for a long term predictor (16) included in a speech codec, characterized in that the method comprises the steps of: first searching the probable pitch periods skipping a first number (M) of pitch periods, to find the most adequate pitch period (D₁) among the searched pitch periods, and second searching a second number of pitch periods including said pitch period (D₁) and pitch periods neighboring said pitch period (D₁) on both sides, to find the most adequate pitch period (D₂) among the second number of pitch periods.
Claim 3
Dependent Claim
90 words
A searching method as claimed in claim 1, wherein said speech codec further includes a short term predictor (24), and said first and second searching steps comprise the steps of: estimating a total squared prediction error between a speech signal and a predictive signal thereof predicted with said long term predictor (16) and said short term predictor (24), for each searched pitch period, and selecting a pitch period which generates the least total squared prediction error among the searched pitch periods for the most adequate pitch period (D₁ , D₂).
Claim 4
Dependent Claim
45 words
A searching method as claimed in claim 2, wherein said estimating step included in said first searching step comprises a step of smoothing said speech signal and said predictive signal at a time constant corresponding to said first number (M), before calculating said prediction error.
Claim 5
Dependent Claim
150 words
A pitch period searching circuit for searching pitch periods which are probable in speech signals for the most adequate pitch period for a long term predictor (16) included in a speech codec, comprising arithmetic means (30) for estimating suitability of the pitch period, characterized in that the circuit further comprises: searching means (40) for searching the probable pitch periods skipping a first number (M) of pitch periods, to find the most adequate pitch period (D₁) among the searched pitch periods based on estimation by said arithmetic means (30), in response to a first search command, and for searching a second number of pitch periods including said pitch period (D₁) and pitch periods neighboring said pitch period (D₁) on both sides, to find the most adequate pitch period (D₂) among the second number of pitch periods based on estimation by said arithmetic means (30), in response to a second search command.
Claim 6
Dependent Claim
150 words
A pitch period searching circuit for searching pitch periods which are probable in speech signals for the most adequate pitch period for a long term predictor (16) included in a speech codec, comprising arithmetic means (30) for estimating suitability of the pitch period, characterized in that the circuit further comprises: searching means (40) for searching the probable pitch periods skipping a first number (M) of pitch periods, to find the most adequate pitch period (D₁) among the searched pitch periods based on estimation by said arithmetic means (30), in response to a first search command, and for searching a second number of pitch periods including said pitch period (D₁) and pitch periods neighboring said pitch period (D₁) on both sides, to find the most adequate pitch period (D₂) among the second number of pitch periods based on estimation by said arithmetic means (30), in response to a second search command.
Claim 7
Dependent Claim
78 words
A searching circuit as claimed in claim 4, wherein said speech codec further comprises a short term predictor (24), said arithmetic means (30) estimates a total squared prediction error between a speech signal and a predictive signal thereof predicted with said long term predictor (16) and said short term predictor (24), and said searching means (40) select the most adequate pitch period (D₁ , D₂) which generates the least total squared prediction error among the searched pitch periods.
Claim 8
Dependent Claim
82 words
A searching circuit as claimed in claim 5, further comprises two smoothing means (32, 34) for smoothing said speech signal and said predictive signal, respectively, at a time constant corresponding to said first number (M), and two switch means (36, 38) for bypassing said two smoothing means (32, 34), respectively, wherein said searching means (40) open said switch means (36, 38) in response to said first search command, and close said switch means (36, 38) in response to said second search command.
References Cited (Backward Citations)
No citation records indexed.
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