Audio coding device, method, and computer-readable recording medium storing program
First Claim
1. An audio coding device comprising:
- a time-to-frequency converter that performs time-to-frequency conversion on each frame of a signal in at least one channel included in an audio signal in a predetermined length of time in order to convert the signal in the at least one channel to a frequency signal;
a complexity calculator that calculates a first value indicating complexity of the frequency signal for each of the at least one channel, based on a spectral power of a frequency bandwidth and a masking threshold representing a power of a lower limit frequency signal of a sound that a listener is able to hear;
a bit allocation controller that;
determines a second value indicating a number of bits to be allocated to each frame of audio signals for each of the at least one channel so that the second value increases as the first value increases,calculates a third value indicating a number of bits that have been required to code each frame of the frequency signal so that reproduced sound quality of a previous frame meets a prescribed criterion, andupdates the second value so that the second value increases as an estimation error indicating an estimated number of error bits that have occurred in the previous frame; and
a coder that codes the frequency signal in each channel so that a number of available bits for each frame of coded audio signals does not exceeds the updated second value.
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Abstract
An audio coding device includes a time-to-frequency converter that performs time-to-frequency conversion on each frame of a signal in at least one channel included in an audio signal in a predetermined length of time in order to convert the signal in the at least one channel to a frequency signal; a complexity calculator that calculates complexity of the frequency signal for each of the at least one channel. The audio further includes a bit allocation controller that determines a number of bits to be allocated to each of at least one channel so that more bits are allocated to the each of the at least one channel as the complexity of the each of at least one channel increases, and increases the number of bits to be allocated as an estimation error in the number; and a coder that codes the frequency signal.
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Citations
19 Claims
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1. An audio coding device comprising:
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a time-to-frequency converter that performs time-to-frequency conversion on each frame of a signal in at least one channel included in an audio signal in a predetermined length of time in order to convert the signal in the at least one channel to a frequency signal; a complexity calculator that calculates a first value indicating complexity of the frequency signal for each of the at least one channel, based on a spectral power of a frequency bandwidth and a masking threshold representing a power of a lower limit frequency signal of a sound that a listener is able to hear; a bit allocation controller that; determines a second value indicating a number of bits to be allocated to each frame of audio signals for each of the at least one channel so that the second value increases as the first value increases, calculates a third value indicating a number of bits that have been required to code each frame of the frequency signal so that reproduced sound quality of a previous frame meets a prescribed criterion, and updates the second value so that the second value increases as an estimation error indicating an estimated number of error bits that have occurred in the previous frame; and a coder that codes the frequency signal in each channel so that a number of available bits for each frame of coded audio signals does not exceeds the updated second value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An audio coding method comprising:
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performing time-to-frequency conversion on each frame of a signal in at least one channel included in an audio signal in a predetermined length of time in order to convert the signal in the at least one channel to a frequency signal; calculating a first value indicating complexity of the frequency signal for each of the at least one channel, based on a spectral power of a frequency bandwidth and a masking threshold representing a power of a lower limit frequency signal of a sound that a listener is able to hear; determining a second value indicating a number of bits to be allocated to each frame of audio signals for each of the at least one channel so that the second value increases as the first value increases; calculating a third value indicating a number of bits that have been required to code each frame of the frequency signal so that reproduced sound quality of a previous frame meets a prescribed criterion; updating the second value so that the second value increases as an estimation error indicating an estimated number of error bits that have occurred in the previous frame increases; and coding the frequency signal in each channel so that a number of available bits for each frame of coded audio signals does not exceeds the updated second value. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A non-transitory, computer-readable recording medium storing an audio coding computer program that causes a computer to execute a process comprising:
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performing time-to-frequency conversion on each frame of a signal in at least one channel included in an audio signal in a predetermined length of time in order to convert the signal in the at least one channel to a frequency signal; calculating a first value indicating complexity of the frequency signal for each of the at least one channel, based on a spectral power of a frequency bandwidth and a masking threshold representing a power of a lower limit frequency signal of a sound that a listener is able to hear; determining a second value indicating a number of bits to be allocated to each frame of audio signals for each of the at least one channel so that the second value increases as the first value increases; calculating a third value indicating a number of bits that have been required to code each frame of the frequency signal so that reproduced sound quality of a previous frame meets a prescribed criterion; updating the second value so that the second value increases as an estimation error indicating an estimated number of error bits that have occurred in the previous frame increases; and coding the frequency signal in each channel so that a number of available bits for each frame of coded audio signals does not exceeds the updated second value. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification