EP1335350A2
Expired / Lapsed
EP
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Pitch extraction methods and systems for speech coding using interpolation techniques
Assignee: Broadcom Corp
•
Filing: 2003-02-04
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Granted: —
•
Expires: 2023-02-04
Abstract
Abstract A method of determining a pitch period of an audio signal using a correlation-based signal derived from the audio signal. The correlation-based signal includes known peaks each corresponding to a respective one of known time lags. The known peaks includes a global maximum peak. The method comprises: (a) determining if a candidate peak among the local peaks exceeds a peak threshold; (b) determining if a candidate time lag corresponding to the candidate peak is within a predetermined range of at least one integer sub-multiple of the time lag corresponding to the global maximum peak; and (c) setting the pitch period equal to the candidate time lag when the determinations of both steps (a) and (b) are true.
Inventors
- 👤 Juin-Hwey Chen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 02:19
CPC Classifications
G; G10; G10L; G10L25/00; G10L25/90
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
118 words
A method of determining a pitch period of an audio signal using a
correlation-based signal derived from the audio signal, the correlation-based signal
including known peaks, each of the peaks corresponding to a respective one of
known time lags, the known peaks including a global maximum peak, comprising: (a) determining if a candidate peak among the local peaks exceeds a
peak threshold; (b) determining if a candidate time lag corresponding to the candidate
peak is within a predetermined range of at least one integer sub-multiple of the
time lag corresponding to the global maximum peak; and (c) setting the pitch period equal to the candidate time lag when the
determinations of both steps (a) and (b) are true.
Claim 2
Dependent Claim
38 words
The method of claim 1, wherein step (a) comprises determining if
the candidate peak among the local peaks (i) exceeds the peak threshold, and (ii) is
within a predetermined time lag range of a previously determined pitch period.
Claim 3
Dependent Claim
15 words
The method of claim 1 or 2, further comprising performing step (a)
before step (b).
Claim 4
Dependent Claim
60 words
The method of claim 1, 2 or 3, further comprising: prior to step (a), determining if the candidate time lag is less than the time
lag corresponding to the global maximum peak; and performing steps (a), (b) and (c) only if the candidate time lag is
determined to be less than the time lag corresponding to the global maximum peak.
Claim 5
Independent Claim
18 words
The method of any preceding claim, wherein the peak threshold is a
fraction of the global maximum peak.
Claim 6
Independent Claim
26 words
The method of any preceding claim, wherein the correlation-based
signal is a Normalized Correlation Square (NCS) signal, and the peaks are peaks of
the NCS signal.
Claim 7
Independent Claim
33 words
The method of any preceding claim, wherein the candidate time lag
corresponding to the candidate peak is within a predetermined time lag range of a
previously determined pitch period of the audio signal
Claim 8
Independent Claim
189 words
A method of determining a pitch period of an audio signal based on
a correlation-based signal derived from the audio signal, the correlation-based
signal including known local peaks each corresponding to a respective known time
lag, the local peaks including a known global maximum local peak, each local
peak corresponding to a known interpolated peak, comprising: (a) receiving a candidate local peak (CLP) indicator having either (i) a first indicator value indicating that a CLP exits among
the local peaks, the CLP corresponding to a time lag within a predetermined range of a
previously determined pitch period of the audio signal, and an interpolated peak exceeding a first peak threshold,
or (ii) a second indicator value indicating that no CLP exists
among the local peaks; (b) if the second indicator value is received, then setting the pitch
period equal to the time lag corresponding to the global maximum local peak; and (c) if the first indicator value is received, and if the CLP is the same as
the global maximum local peak, then setting the pitch period equal to the time lag
corresponding to the global maximum local peak.
Claim 9
Dependent Claim
17 words
The method of claim 8, wherein the first indicator includes the time
lag corresponding to the CLP.
Claim 10
Dependent Claim
143 words
The method of claim 8 or 9, further comprising: (d) if the first indicator value is received, and if the CLP is not the same
as the global maximum local peak, then determining if the time lag corresponding to the CLP is less than the
time lag corresponding to the global maximum local peak; and (e) if the determination of step (d) is true, then (e)(i) determining if the CLP exceeds a second peak threshold,
and (e)(ii) if the CLP exceeds the second peak threshold,
then determining if the time lag corresponding to the CLP is
within a predetermined range of at least one integer sub-multiple of
the time lag corresponding to the global maximum local peak, and (e)(iii) if the determinations of both steps (e)(i) and (e)(ii) are true,
then setting the pitch period equal to the time lag of the CLP.
Claim 11
Dependent Claim
31 words
The method of claim 10 or 11, further comprising: performing steps (e)(ii) and (e)(iii) only when the time lag
corresponding to the CLP is within a predetermined pitch period search range.
Claim 12
Dependent Claim
44 words
The method of claim 10 or 11, wherein step (e) further comprises: (e)(iv) if either the determination of step (e)(i) or the determination
of step (e)(ii) is false, then setting the pitch period equal to the time lag of the global
maximum local peak.
Claim 13
Dependent Claim
54 words
The method of claim 10, 11 or 12, further comprising: (f) if the determination of step (d) is false, then (f)(i) determining if the CLP exceeds a third peak
threshold, and (f)(ii) if the CLP exceeds the third peak threshold, then setting the pitch period equal to the time lag
corresponding to the CLP.
Claim 14
Dependent Claim
38 words
The method of claim 13, wherein step (f) further comprises: (f)(iii) if the CLP does not exceed the third peak threshold, then setting the pitch period equal to the time lag corresponding
to the global maximum local peak.
Claim 15
Independent Claim
139 words
A method of determining a pitch period of an audio signal using a
correlation-based signal derived from the audio signal, the correlation-based signal
including known peaks at corresponding known time lags, comprising: (a) searching the correlation-based signal for a first time lag
corresponding to a global maximum interpolated peak of the correlation-based
signal; (b) searching the correlation-based signal for a maximum interpolated
peak corresponding to a second time lag within a predetermined time lag range of a
previously determined pitch period of the audio signal; (c) searching the correlation-based signal for a third time lag; and (d) selecting as a time lag indicative of the pitch period a preferred one
of the first time lag if found in step (a), the second time lag if found in step (b), and the third time lag if found in step (c).
Claim 16
Dependent Claim
61 words
The method of claim 15, wherein step (a) comprises: (a)(i) determining a largest interpolated peak and its corresponding
interpolated time lag around each of at least some of the known peaks; and (a)(ii) selecting the global maximum interpolated peak and the
corresponding first time lag from among the largest interpolated peaks and their
corresponding interpolated time lags determined in step (a)(i).
Claim 17
Dependent Claim
23 words
The method of claim 15 or 16, wherein step (c) comprises: searching the correlation-based signal using an integer multiple time lag
extraction technique.
Claim 18
Dependent Claim
45 words
The method of claim 17, wherein the integer multiple time lag
extraction technique includes searching through interpolated time lags of the
correlation-based signal and checking whether any of the interpolated time lags
corresponds to a sufficiently large known peak near every integer multiple of itself.
Claim 19
Dependent Claim
64 words
The method of any of claim 15 to 18, wherein if a second time lag
was found in step (b), then step (d) comprises selecting the second time lag as the
preferred time lag if the second time lag is (i) less that the first time lag, and (ii) within a predetermined time lag range of an integer sub-multiple of the
first time lag.
Claim 20
Dependent Claim
36 words
The method of any of claim 15 to 19, further comprising: (e) selecting a predetermined time lag if none of the first, second and
third time lags were found in respective steps (a), (b) and (c).
Claim 21
Dependent Claim
139 words
A computer program for determining a pitch period of an audio
signal using a correlation-based signal derived from the audio signal, the
correlation-based signal including known peaks, each of the known peaks
corresponding to a respective one of known time lags, the known peaks including a
global maximum peak, the program, when executed by one or more processors,
causing the one or more processors to perform the steps of: (a) determining if a candidate peak among the local peaks exceeds a
peak threshold; (b) determining if a candidate time lag corresponding to the candidate
peak is within a predetermined range of at least one integer sub-multiple of the
time lag corresponding to the global maximum peak; and (c) setting the pitch period equal to the candidate time lag when the
determinations of both steps (a) and (b) are true.
Claim 22
Dependent Claim
39 words
The computer program of claim 21, wherein step (a) comprises
determining if the candidate peak among the local peaks (i) exceeds the peak
threshold, and (ii) is within a predetermined time lag range of a previously
determined pitch period.
Claim 23
Dependent Claim
20 words
The computer program of claim 21 or 22, wherein the program is
adapted to perform step (a) before step (b).
Claim 24
Dependent Claim
70 words
The computer program of claim 21, 22 or 23, wherein the program
is adapted to perform the further steps of: prior to step (a), determining if the candidate time lag is less than the time
lag corresponding to the global maximum peak; and performing steps (a), (b) and (c) only if the candidate time lag is
determined to be less than the time lag corresponding to the global maximum peak.
Claim 25
Dependent Claim
22 words
The computer program of any of claims 21 to 24, wherein the peak
threshold is a fraction of the global maximum peak.
Claim 26
Dependent Claim
30 words
The computer program of any of claims 21 to 25, wherein the
correlation-based signal is a Normalized Correlation Square (NCS) signal, and the
peaks are peaks of the NCS signal.
Claim 27
Dependent Claim
37 words
The computer program of any of claims 21 to 26, wherein the
candidate time lag corresponding to the candidate peak is within a predetermined
time lag range of a previously determined pitch period of the audio signal.
Claim 28
Dependent Claim
159 words
A computer program for determining a pitch period of an audio
signal using a correlation-based signal derived from the audio signal, the
correlation-based signal including known peaks at corresponding known time lags,
the programs when executed by one or more processors, causing the one or more
processors to perform the steps of: (a) searching the correlation-based signal for a first time lag
corresponding to a global maximum interpolated peak of the correlation-based
signal; (b) searching the correlation-based signal for a maximum interpolated
peak corresponding to a second time lag within a predetermined time lag range of a
previously determined pitch period of the audio signal; (c) searching the correlation-based signal for a third time lag; and (d) selecting as a time lag indicative of the pitch period a preferred one
of the first time lag if found in step (a), the second time lag if found in step (b), and the third time lag if found in step (c).
Claim 29
Dependent Claim
62 words
The computer program of claim 28, wherein step (a) comprises: (a)(i) determining a largest interpolated peak and its corresponding
interpolated time lag around each of at least some of the known peaks; and (a)(ii) selecting the global maximum interpolated peak and the
corresponding first time lag from among the largest interpolated peaks and their
corresponding interpolated time lags determined in step (a)(i).
Claim 30
Dependent Claim
24 words
The computer program of claim 28 or 29, wherein step (c)
comprises: searching the correlation-based signal using an integer multiple time lag
extraction technique.
Claim 31
Dependent Claim
46 words
The computer program of claim 30, wherein the integer multiple
time lag extraction technique includes searching through interpolated time lags of
the correlation-based signal and checking whether any of the interpolated time lags
corresponds to a sufficiently large known peak near every integer multiple of itself.
Claim 32
Dependent Claim
65 words
The computer program of any of claims 28 to 31, wherein if a
second time lag was found in step (b), then step (d) comprises selecting the second
time lag as the preferred time lag if the second time lag is (i) less that the first time lag, and (ii) within a predetermined time lag range of an integer sub-multiple of the
first time lag.
Claim 33
Dependent Claim
46 words
The computer program of any of claims 28 to 32, wherein the
program is adopted to perform the further step of: (e) selecting a predetermined time lag if none of the first, second and
third time lags were found in respective steps (a), (b) and (c).
Claim 34
Dependent Claim
15 words
A computer readable medium carrying the computer program of any
of claims 21 to 33.
Claim 35
Independent Claim
154 words
An apparatus for determining a pitch period of an audio signal using
a correlation-based signal derived from the audio signal, the correlation-based
signal including known peaks at corresponding known time lags, comprising: a first module for searching the correlation-based signal for a first time lag
corresponding to a global maximum interpolated peak of the correlation-based
signal; a second module for searching the correlation-based signal for a maximum
interpolated peak corresponding to a second time lag within a predetermined time
lag range of a previously determined pitch period of the audio signal; a third module for searching the correlation-based signal for a third time
lag; and a fourth module for selecting as a time lag indicative of the pitch period a
preferred one of the first time lag if found by the first module, the second time lag if found by the second module, and the third time lag if found by the third module.
Claim 36
Dependent Claim
58 words
The apparatus of claim 35, wherein the first module is configured
to: determine a largest interpolated peak and its corresponding interpolated
time lag around each of at least some of the known peaks; and select the global maximum interpolated peak and the corresponding first
time lag from among the largest interpolated peaks and their corresponding
interpolated time lags.
Claim 37
Dependent Claim
26 words
The apparatus of claim 35 or 36, wherein the third module is
configured to search the correlation-based signal using an integer multiple time lag
extraction technique.
Claim 38
Dependent Claim
45 words
The apparatus of claim 37, wherein the integer multiple time lag
extraction technique includes searching through interpolated time lags of the
correlation-based signal and checking whether any of the interpolated time lags
corresponds to a sufficiently large known peak near every integer multiple of itself.
Claim 39
Independent Claim
68 words
The apparatus of any of claims 35 to 38, wherein if a second time
lag was found by the second module, then the fourth module is configured to select
the second time lag as the preferred time lag if the second time lag is (i) less that the first time lag, and (ii) within a predetermined time lag range of an integer sub-multiple of the
first time lag.
Claim 40
Independent Claim
41 words
The apparatus of any of claims 35 to 39, wherein the fourth module
is configured to select a predetermined time lag if none of the first, second and
third time lags were found by the respective first, second and third modules.
References Cited (Backward Citations)
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