Speech audio encoding device, speech audio decoding device, speech audio encoding method, and speech audio decoding method
First Claim
1. A speech/audio coding apparatus, comprising:
- a receiver that receives a time-domain speech input signal;
a memory; and
a processor thattransforms a time-domain speech input signal into a frequency-domain spectrum;
divides a frequency region of the spectrum in an extended band into a plurality of bands; and
sets a limited band for a respective divided band, when a difference between a first frequency with a first maximum amplitude in a spectrum of the divided band in a preceding frame and a second frequency with a second maximum amplitude in a spectrum of the divided band in a current frame is below a threshold, a width of the limited band in the current frame being narrower than the divided band and the limited band including the first frequency for encoding the spectrum in the limited band in the current frame for transmitting to a decoder side, and not for encoding a spectrum outside the limited band within its respective divided band in the current frame.
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Abstract
A speech/audio coding apparatus and method is provided. The number of encoding bits allocated to encoding of extended-band spectrum is reduced while degradation of sound quality in the extended band is suppressed. A band compression unit creates combinations of sub-band spectra in pairs of two samples each in order from a low-range side in a band compression target sub-band, selects a spectrum having a large absolute-value amplitude among the combinations, and arranges the selected spectrum close to the low-range side on a frequency axis. A number-of-units recalculation unit redistributes bits saved in the sub-band for which band compression was performed to a low range outside the extended band, and redistributes the number of units on the basis of the redistributed bits.
12 Citations
12 Claims
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1. A speech/audio coding apparatus, comprising:
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a receiver that receives a time-domain speech input signal; a memory; and a processor that transforms a time-domain speech input signal into a frequency-domain spectrum; divides a frequency region of the spectrum in an extended band into a plurality of bands; and sets a limited band for a respective divided band, when a difference between a first frequency with a first maximum amplitude in a spectrum of the divided band in a preceding frame and a second frequency with a second maximum amplitude in a spectrum of the divided band in a current frame is below a threshold, a width of the limited band in the current frame being narrower than the divided band and the limited band including the first frequency for encoding the spectrum in the limited band in the current frame for transmitting to a decoder side, and not for encoding a spectrum outside the limited band within its respective divided band in the current frame. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A speech/audio coding method, comprising:
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transforming a time-domain speech input signal into a frequency-domain spectrum; dividing a frequency region of the spectrum in an extended band into a plurality of bands; and setting a limited band for a respective divided band, when a difference between a first frequency with a first maximum amplitude in a spectrum of the divided band in a preceding frame and a second frequency with a second maximum amplitude in a spectrum of the divided band in a current frame is below a threshold, a width of the limited band in the current frame being narrower than the divided band, and the limited band including the first frequency for encoding the spectrum in the limited band in the current frame for transmitting to a decoder side, and not for encoding a spectrum outside the limited band within its respective divided band in the current frame. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification