EP0599664A2
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EP
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Voice encoder and method of voice encoding
Assignee: NEC Corp
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Filing: 1993-11-29
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Granted: —
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Expires: 2013-11-29
Abstract
Abstract A voice encoder which pauses outputting codewords in accordance with the absence of voice activity. An input aural signal is divided into frames and inputted to the voice encoder. The voice encoder has a voice activity detection circuit for determining at each frame whether voice activity is absent or present, a voice encoding circuit, a background noise update judging circuit for detecting a change in the characteristics of the input aural signal, and a control circuit. If the absence of voice activity is detected, the control circuit causes the frame at that time to be encoded as a background noise frame, and then pauses the operation of the voice encoding circuit. If the presence of voice activity is detected, the operation of the voice encoding circuit is resumed. Furthermore, if the voice encoding circuit is not in operation when a change in the characteristics of the input aural signal is detected, the control circuit causes the voice encoding circuit to encode the frame at that time as a background noise frame and then again stop the operation of the voice encoding circuit. A method of voice encoding is also disclosed.
Inventors
- 👤 Toshihiro C/O Nec Corporation Hayata
- 👤 Yoshihiro C/O Nec Corporation Unno
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 08:56
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/012; G10L19/04; G10L19/16; G10L19/18; G10L19/20; G10L25/00; G10L25/78; G10L25/93
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
112 words
A voice encoder comprising: voice activity detection means for analyzing an input aural signal and judging whether voice activity is absent or present; voice encoding means for encoding the input aural signal; background noise update judging means for detecting a change in the characteristicsof the input aural signal when voice activity is absent; and control means for temporarily stopping operation of the voice encoding means when it is detected that voice activity is absent, and,when a change in the characteristics of the input aural signal is detected by the background noise update judging means, causing the voice encoding means to encode the input aural signal at that time as background noise data.
Claim 2
Dependent Claim
25 words
The voice encoder of claim 1 wherein the input aural signals are divided into frames and inputted, and encoding is carried out frame by frame.
Claim 3
Dependent Claim
40 words
The voice encoder of claim 1 or 2 wherein, when it is detected that voice activity is absent, operation of the voice encoding means is temporarily stopped after encoding the input aural signal at that time as background noise data.
Claim 4
Dependent Claim
24 words
The voice encoder of claim 3 wherein the background noise data is outputted at predetermined time intervals while the absence of voice activity continues.
Claim 5
Dependent Claim
172 words
A voice encoder comprising: input means for inputting an input aural signal divided into frames; synthetic filter coefficient calculation means for analyzing the input aural signal and calculating a synthetic filter coefficient; frame energy calculation means for analyzing the input aural signal and calculating a frame energy value for each of the frames; voice activity detection means for determining whether voice activity is absent or present; voice encoding means for encoding the input aural signal frame by frame based on the synthetic filter coefficient and the frame energy value; background noise update judging means for detecting a change in the characteristics of the input aural signal when voice activity is absent; and control means for temporarily stopping the operation of the voice encoding means when it is detected that voice activity is absent, and,when a change in the characteristics of the input aural signal is detected by the background noise update judging means, causing the voice encoding means to encode the input aural signal at that time as a background noise frame.
Claim 6
Dependent Claim
31 words
The voice encoder of claim 5 wherein the voice activity detection means determines whether voice activity is absent or present based on the synthetic filter coefficient and the frame energy value.
Claim 7
Dependent Claim
41 words
The voice encoder of claim 5 or 6 wherein the background noise update judging means detects a change in the characteristics of the input aural signal based on at least one of the synthetic filter coefficient and the frame energy value.
Claim 8
Dependent Claim
43 words
The voice encoder of claim 5, 6 or 7 wherein, when it is detected that voice activity is absent, the operation of the voice encoding means is temporarily stopped after encoding the input aural signal at that time as the background noise frame.
Claim 9
Dependent Claim
28 words
The voice encoder of any of claims 5 to 8 wherein the background noise frame is outputted at predetermined time intervals while the absence of voice activity continues.
Claim 10
Dependent Claim
61 words
The voice encoder of claim 7 wherein the background noise update judging means compares a current frame and a previously outputted background noise frame, and judges that a change has occurred in the characteristics of the input aural signal if the change of at least one of the synthetic filter coefficient and the frame energy value exceeds a predetermined threshold value.
Claim 11
Dependent Claim
51 words
The voice encoder of claim 7 or 10 wherein it is judged that a change has occurred in the input aural signal if the ratio of the frame energy value of the current frame to the frame energy value of the previously outputted background noise frame deviates from a predetermined range.
Claim 12
Dependent Claim
67 words
The voice encoder of claim 7, 10 or 11 wherein it is judged that a change has occurred in the characteristics of the input aural signal if the area of the difference between the spectral characteristics shown by the synthetic filter coefficient of the current frame and the spectral characteristics shown by the synthetic filter coefficient of the previously outputted background noise frame exceeds a predetermined value.
Claim 13
Dependent Claim
64 words
The voice encoder of Claim 2 or of any of Claims 5 to 12 wherein judgment of the absence or presence of voice activity is carried out at each of the frames, and wherein operation of the voice encoding means is resumed if it is judged that voice activity is present when the operation of the voice encoding means is in a rest state.
Claim 14
Independent Claim
88 words
A method of voice encoding comprising: analyzing an input aural signal and judging whether voice activity is absent or present; encoding the input aural signal; detecting a change in the characteristics of the input aural signal when voice activity is absent; and wherein encoding is temporarily stopped when it is detected that voice activity is absent, and, when a change in the characteristics of the input aural signal is detected when voice activity is absent, the input aural signal at that time is encoded as background noise data.
Claim 15
Independent Claim
131 words
A method of voice encoding comprising: inputting an input aural signal divided into frames; analyzing the input aural signal and calculating a synthetic filter coefficient; analyzing the input aural signal and calculating a frame energy value for each of the frames; determining whether voice activity is absent or present; encoding the input aural signal frame by frame based on the synthetic filter coefficient and the frame energy value; detecting a change in the characteristics of the input aural signal when voice activity is absent; and wherein encoding is temporarily stopped when it is detected that voice activity is absent, and, when a change in the characteristics of the input aural signal is detected when voice activity is absent, the input signal at that time is encoded as a background noise frame.
References Cited (Backward Citations)
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