Scalable speech coding/decoding apparatus, method, and medium having mixed structure
First Claim
1. A scalable speech coding apparatus having a mixed structure, the apparatus comprising:
- a band divider to divide a speech input signal into a low-band signal and a high-band signal according to a specific frequency, and outputting the low-band signal and the high-band signal;
a low-band coder to output a low-band first index by coding the low-band signal, to transmit information required for coding the high-band signal to a high-band coder, and to transmit a error signal obtained from the low-band signal and a signal generated during coding the low-band signal;
a high-band coder to output a high-band second index obtained when the high-band signal is coded by using information received from the low-band coder, and to transmit a second error signal obtained from the high-band signal and a signal generated during coding the high-band signal;
a wide-band coder to obtain a wide-band third index from the first and second error signals using a modified discrete cosine transform (MDCT); and
a bit-stream generator to output a scalable bit-stream composed of the low-band first index received from the low-band coder, the high-band second index received from the high-band coder, and the wide-band third index received from the wide-band coder.
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Abstract
Provided are a scalable wide-band speech coding/decoding apparatus, method, and medium. An input wide-band speech input signal is first divided into a low-band signal and a high-band signal. The divided low-band signal is then coded using a code excited linear prediction (CELP) method. The divided high-band signal is coded using a harmonic method. A signal representing a difference between a synthetic signal obtained from the low-band and the high band, and a signal input to the low-band and the high-band is then coded using a modified discrete cosine transform (MDCT) method. The coded signal is then multiplexed. The multiplexed signal is then output. Accordingly, high quality speech can be achieved for all layers.
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Citations
32 Claims
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1. A scalable speech coding apparatus having a mixed structure, the apparatus comprising:
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a band divider to divide a speech input signal into a low-band signal and a high-band signal according to a specific frequency, and outputting the low-band signal and the high-band signal; a low-band coder to output a low-band first index by coding the low-band signal, to transmit information required for coding the high-band signal to a high-band coder, and to transmit a error signal obtained from the low-band signal and a signal generated during coding the low-band signal; a high-band coder to output a high-band second index obtained when the high-band signal is coded by using information received from the low-band coder, and to transmit a second error signal obtained from the high-band signal and a signal generated during coding the high-band signal; a wide-band coder to obtain a wide-band third index from the first and second error signals using a modified discrete cosine transform (MDCT); and a bit-stream generator to output a scalable bit-stream composed of the low-band first index received from the low-band coder, the high-band second index received from the high-band coder, and the wide-band third index received from the wide-band coder. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A scalable speech coding method having a mixed structure, the method comprising:
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(a) dividing a speech input signal into a low-band signal and a high-band signal according to a specific frequency, and outputting the low-band signal and the high-band signal; (b) generating and outputting a low-band first index by coding the output low-band signal, and outputting specific information required for coding the high-band signal and a first error signal obtained from the low-band signal; (c) coding the output high-band signal by using the specific information, and outputting a high-band second index and a second error signal obtained from the high-band signal; (d) obtaining a wide-band third index from the first and second error signals using a modified discrete cosine transform (MDCT); and (e) outputting a scalable bit-stream composed of the low-band first index, the high-band second index, and the wide-band third index. - View Dependent Claims (8, 9, 10, 11, 12, 25, 26, 27, 28)
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13. A scalable speech decoding apparatus having a mixed structure, the apparatus comprising:
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a bit-stream divider to receive a scalable bit-stream transmitted at a specific transmission rate according to a network condition, and to generate a low-band signal, a high-band signal, and a wide band signal by dividing the scalable bit-stream according to a frequency band used in reproduction; a low-band decoder to receive the low-band signal into which the scalable bitstream is divided by the bit-stream divider, to decode and output the received low-band signal, and to transmit specific information required for decoding a high-band signal among coefficients decoded in a low-band; a high-band decoder to decode and output the high-band signal into which the scalable bit-stream is divided by the bitstream divider, using the specific information; a wide-band decoder to decode the wide-band signal into which the scalable bitstream is divided by the bit-stream divider, and to divide and output the decoded wide-band signal into a low-band signal and a high-band signal according to a specific frequency; and a band combiner to output a wide-band synthetic signal of a combined band using a signal output from the low-band decoder, a signal output from the high-band decoder, the low-band signal output from the wide-band decoder, and the high-band signal output from the wide-band decoder. - View Dependent Claims (14, 15, 16)
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17. A scalable speech decoding method having a mixed structure, the method comprising:
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(a) receiving a scalable bit-stream transmitted at a specific transmission rate according to a network condition, and dividing and outputting the scalable bit-stream into a low-band signal, a high-band signal, and a wide-band signal according to a frequency band used for reproduction; (b) receiving the low-band signal of the scalable bitstream, decoding and outputting the received low-band signal, and outputting information on a pitch signal among coefficients decoded in a low-band; (c) receiving the high-band signal of the scalable bitstream and the pitch signal information, and decoding and outputting the high-band signal by using the pitch signal information; (d) receiving and decoding the wide-band signal of the scalable bitstream, and dividing and outputting the decoded wide-band signal into a low-band signal and a high-band signal according to a specific frequency; and (e) outputting a wide-band synthetic signal of a combined band by using a signal output in (b), a signal output in (c), a low-band signal output in (d), and a high-band signal output in (d). - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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29. A scalable speech coding method having a mixed structure, the apparatus comprising:
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dividing a speech input signal into a low-band signal and a high-band signal according to a specific frequency, and outputting the low-band signal and the high-band signal; outputting a low-band first index by coding a low-band signal, outputting information required for coding a high-band signal, and outputting a first error signal obtained from the low-band signal; outputting a high-band second index obtained when the high-band signal is coded by using the information required for coding a high-band signal, and outputting a second error signal obtained from the high-band signal; obtaining a wide-band third index from the first and second error signals using a modified discrete cosine transform (MDCT); and outputting a scalable bit-stream composed of the low-band first index, the high-band second index, and the wide-band third index. - View Dependent Claims (30)
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31. A scalable speech decoding method having a mixed structure for decoding a scalable bit-stream, the method comprising:
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(a) receiving a low-band signal of the scalable bitstream, decoding and outputting the received low-band signal, and outputting information on a pitch signal among coefficients decoded in a low-band; (b) receiving a high-band signal of the scalable bitstream and the pitch signal information, and decoding and outputting the high-band signal by using the pitch signal information; (c) receiving and decoding a wide-band signal of the scalable bitstream, and dividing and outputting the decoded wide-band signal into a low-band signal and a high-band signal according to a specific frequency; and (d) outputting a wide-band synthetic signal of a combined band by using a signal output in (a), a signal output in (b), a low-band signal output in (c), and a high-band signal output in (c). - View Dependent Claims (32)
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Specification