VOICE CODING DEVICE, VOICE DECODING DEVICE AND THEIR METHODS
First Claim
1. A speech coding apparatus comprising:
- a first layer coding section that encodes components in a lower band of an input speech signal and acquires first layer encoded data, the lower band being lower than a predetermined frequency;
a deciding section that decides whether or not there are the components in the lower band of the speech signal; and
a second layer coding section that, if there are the components in the lower band of the speech signal, encodes components in a higher band of the speech signal using the components in the lower band of the speech signal and acquires second layer encoded data, the higher band being equal to or higher than the predetermined frequency, and that, if there are not the components in the lower band of the speech signal, encodes the components in the higher band of the speech signal using a predetermined signal allocated in the lower band of the speech signal and acquires second layer encoded data.
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Accused Products
Abstract
It is an object to disclose a voice coding device, etc. in which the deterioration of a voice quality of a decoded signal can be reduced in the case that low frequency domain components of a spectrum are used for coding high frequency domain components and that no low frequency domain components exist. In this voice coding device, a frequency domain transform unit (101) generates an input spectrum from an input voice signal, a first layer coding unit (102) codes a lower frequency domain portion of the input spectrum to generate first layer coded data, a first layer decoding unit (103) decodes the first layer coded data to generate a first layer decoded spectrum, a lower frequency domain component judging unit (104) judges if there are low frequency domain components of the first layer decoded spectrum, and a second decoding unit (105); codes high frequency domain components of the input spectrum to generate second layer coded data in the case that the low frequency domain components exist and codes high frequency domain components by using a predetermined signal disposed in the low frequency domain components to generate second layer coded data in the case that the low frequency domain components do not exist.
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Citations
10 Claims
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1. A speech coding apparatus comprising:
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a first layer coding section that encodes components in a lower band of an input speech signal and acquires first layer encoded data, the lower band being lower than a predetermined frequency; a deciding section that decides whether or not there are the components in the lower band of the speech signal; and a second layer coding section that, if there are the components in the lower band of the speech signal, encodes components in a higher band of the speech signal using the components in the lower band of the speech signal and acquires second layer encoded data, the higher band being equal to or higher than the predetermined frequency, and that, if there are not the components in the lower band of the speech signal, encodes the components in the higher band of the speech signal using a predetermined signal allocated in the lower band of the speech signal and acquires second layer encoded data. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A speech decoding apparatus comprising:
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a first layer decoding section that decodes a first layer encoded data acquired by encoding components in a lower band of a speech signal, the lower band being lower than a predetermined frequency; a deciding section that decides whether or not there are the components in the lower band of the speech signal; and a second layer decoding section that decodes second layer encoded data acquired by encoding components in a higher band of the speech signal, using the components in the lower band of the speech signal if there are the components in the lower band of the speech signal, the higher band being equal to or higher than the predetermined frequency, and that decodes the second layer encoded data acquired by encoding the components in the higher band of the speech signal, using a predetermined signal allocated in the lower band of the speech signal if there are not the components in the lower band of the speech signal.
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9. A speech coding method comprising:
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a first step of encoding components in a lower band of an input speech signal and acquiring first layer encoded data, the lower band being lower than a predetermined frequency; a second step of deciding whether or not there are the components in the lower band of the speech signal; and a third step of, if there are the components in the lower band of the speech signal, encoding components in a higher band of the speech signal using the components in the lower band of the speech signal and acquiring second layer encoded data, the higher band being equal to or higher than the predetermined frequency, and, if there are not the components in the lower band of the speech signal, encoding the components in the higher band of the speech signal using a predetermined signal allocated in the lower band of the speech signal and acquiring second layer encoded data.
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10. A speech decoding method comprising:
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a first step of decoding a first layer encoded data acquired by encoding components in a lower band of a speech signal, the lower band being lower than a predetermined frequency; a second step of a deciding whether or not there are the components in the lower band of the speech signal; and a third step of decoding second layer encoded data acquired by encoding components in a higher band of the speech signal, using the components in the lower band of the speech signal if there are the components in the lower band of the speech signal, the higher band being equal to or higher than the predetermined frequency, and decoding the second layer encoded data acquired by encoding the components in the higher band of the speech signal, using a predetermined signal allocated in the lower band of the speech signal if there are not the components in the lower band of the speech signal.
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Specification