Low-frequency emphasis for LPC-based coding in frequency domain
First Claim
1. Audio decoder for decoding a bitstream based on a non-speech audio signal so as to produce from the bitstream a non-speech audio output signal, the bitstream comprising a quantized spectrum and a plurality of linear predictive coding coefficients, the audio decoder comprising:
- a bitstream receiver configured to extract the quantized spectrum and the linear predictive coding coefficients from the bitstream;
a de-quantization device configured to produce a de-quantized spectrum based on the quantized spectrum;
a low frequency de-emphasizer configured to calculate a reverse processed spectrum based on the de-quantized spectrum, wherein spectral lines of the reverse processed spectrum representing a lower frequency than a reference spectral line are deemphasized; and
a control device configured to control the calculation of the reverse processed spectrum by the low frequency de-emphasizer depending on the linear predictive coding coefficients comprised in the bitstream;
wherein the audio decoder comprises combination of a frequency-time converter and an inverse linear predictive coding filter receiving the plurality of linear predictive coding coefficients comprised in the bitstream, wherein the combination is configured to inverse-filter and to convert the reverse processed spectrum into a time domain in order to output the output signal based on the reverse processed spectrum and on the linear predictive coding coefficients.
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Abstract
The invention provides an audio encoder including a combination of a linear predictive coding filter having a plurality of linear predictive coding coefficients and a time-frequency converter, wherein the combination is configured to filter and to convert a frame of the audio signal into a frequency domain in order to output a spectrum based on the frame and on the linear predictive coding coefficients; a low frequency emphasizer configured to calculate a processed spectrum based on the spectrum, wherein spectral lines of the processed spectrum representing a lower frequency than a reference spectral line are emphasized; and a control device configured to control the calculation of the processed spectrum by the low frequency emphasizer depending on the linear predictive coding coefficients of the linear predictive coding filter.
46 Citations
14 Claims
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1. Audio decoder for decoding a bitstream based on a non-speech audio signal so as to produce from the bitstream a non-speech audio output signal, the bitstream comprising a quantized spectrum and a plurality of linear predictive coding coefficients, the audio decoder comprising:
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a bitstream receiver configured to extract the quantized spectrum and the linear predictive coding coefficients from the bitstream; a de-quantization device configured to produce a de-quantized spectrum based on the quantized spectrum; a low frequency de-emphasizer configured to calculate a reverse processed spectrum based on the de-quantized spectrum, wherein spectral lines of the reverse processed spectrum representing a lower frequency than a reference spectral line are deemphasized; and a control device configured to control the calculation of the reverse processed spectrum by the low frequency de-emphasizer depending on the linear predictive coding coefficients comprised in the bitstream; wherein the audio decoder comprises combination of a frequency-time converter and an inverse linear predictive coding filter receiving the plurality of linear predictive coding coefficients comprised in the bitstream, wherein the combination is configured to inverse-filter and to convert the reverse processed spectrum into a time domain in order to output the output signal based on the reverse processed spectrum and on the linear predictive coding coefficients. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. Method for decoding, by an audio decoder, a bitstream based on a non-speech audio signal so as to produce from the bitstream a non-speech audio output signal, the bitstream comprising a quantized spectrum and a plurality of linear predictive coding coefficients, the method comprising:
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extracting the quantized spectrum and the linear predictive coding coefficients from the bitstream; producing a de-quantized spectrum based on the quantized spectrum; calculating a reverse processed spectrum based on the de-quantized spectrum, wherein spectral lines of the reverse processed spectrum representing a lower frequency than a reference spectral line are deemphasized; and controlling the calculation of the reverse processed spectrum depending on the linear predictive coding coefficients comprised in the bitstream; wherein the audio decoder comprises combination of a frequency-time converter and an inverse linear predictive coding filter receiving the plurality of linear predictive coding coefficients comprised in the bitstream, wherein the combination is configured to inverse-filter and to convert the reverse processed spectrum into a time domain in order to output the output signal based on the reverse processed spectrum and on the linear predictive coding coefficients. - View Dependent Claims (14)
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Specification