Speech and music signal coder/decoder

• US 6,865,534 B1
• Filed: 06/15/1999
• Issued: 03/08/2005
• Est. Priority Date: 06/15/1998
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ozawa, Kazunori, Murashima, Atsushi
• Primary Examiner(s): McFadden, Susan
• Assistant Examiner(s): Vo, Huyen X.
• Application Number:
  US09/719,826
• Time in Patent Office: 2,093 Days
• Field of Search: 704/219, 704/220, 704/222, 704/223, 704/227, 704/228, 704/229, 704/230, 704/262, 704/264, 704/265, 704/269, 704500-504
• US Class Current: 704/262
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders

Abstract

It is an object of the invention to excellently code a speech and music signal over all of bands in a speech and music signal code decoding apparatus having a band divided constitution. In order to achieve the object, a residue vector is generated by using an inverse filter (230 of FIG. 3) from a difference vector outputted from a first differencer (180 of FIG. 3). A band selecting circuit (250 of FIG. 3) generates n pieces of subvectors by using a component included in an arbitrary band in the residue vector subjected to orthogonal transformation. An orthogonal transformation coefficient quantizing circuit (260 of FIG. 3) quantizes n pieces of the subvectors.

Claims

1. A speech and music signal coder for producing a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal which is provided by adding a first excitation signal corresponding to a first band of an input signal and a second excitation signal corresponding to a second band of the input signal, said linear prediction synthesis filter setting with a linear prediction coefficient calculated on the basis of said input signal, said speech and music signal coder comprising:

reproduction signal generating means for reproducing a first reproduction signal by driving the linear prediction synthesis filter in response to the excitation signal corresponding to the first band;

residual signal generating means for generating a residual signal by driving a linear prediction inverse filter in response to a differential signal indicative of a difference between the input signal and the first reproduction signal and;

coding means for coding a component corresponding to the second band in the residual signal after orthogonal transformation of the component.

7. The speech and music signal coder as claimed in claim 1, wherein:

a pitch prediction filter is used in generating the excitation signal corresponding to the first band of the input signal.

2. A speech and music signal coder for producing a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal which is provided by adding 3 pieces of excitation signals corresponding to 3 pieces of bands, said speech and music signal coder comprising, said linear prediction synthesis filter setting with a linear prediction coefficient calculated on the basis of said input signal, said speech and music signal coder comprising:

reproduction signal generating means for generating a first and a second reproduction signal by driving the linear prediction synthesis filter in response to the excitation signals corresponding to a first one and a second one of the bands; and

coding means for generating a residual signal by driving a linear prediction inverse filter in response to a differential signal indicative of a difference between an added signal produced by adding the first and the second reproduction signals and the input signal and for coding a component corresponding to a third one of the bands in the residual signal after orthogonal transformation of the component.

3. A speech and music signal coder for producing a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal which is provided by adding N pieces of excitation signals corresponding to N pieces of bands, said speech and music signal coder comprising:

reproduction signal generating means for generating a first through an (N−

1)-th reproduction signal by driving the linear prediction synthesis filter in response to the excitation signals corresponding to a first through and (N−

1)-th band; and

N-th coding means for generating a residual signal by driving a linear prediction inverse filter in response to a differential signal indicative of difference between a signal,;

produced by adding the first through the (N−

1)-th reproduction signals and the input signal and for coding a component corresponding to an N-th band in the residual signal after orthogonal transformation of the component.

4. A speech and music signal coder for producing a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal which is provided by adding 2 pieces of excitation signals corresponding to 2 pieces of bands, said speech and music signal coder comprising:

means for calculating a difference of a first coded decoding signal and the input signal; and

coding means for generating a residual signal by driving a linear prediction inverse filter in response to the differential signal and for coding a component corresponding to an arbitrary one of the bands in the residual signal after subjecting the component to orthogonal transformation.

5. A speech and music signal coder for generating a reproduction signal by driving a linear prediction synthesis filter calculated on the basis of an input signal in response to an excitation signal provided by adding 3 pieces of excitation signals corresponding to 3 pieces of bands, said speech and music signal coder comprising:

means for calculating a differential signal indicative of difference between a signal produced by adding a first and a second coded decoding signal and the input signal; and

coding means for generating a residual signal by driving a linear prediction inverse filter calculated on the basis of the input signal by the differential signal and for coding a component corresponding to an arbitrary band in the residual signal after orthogonal transformation of the component.

6. A speech and music signal coder for producing a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal which is provided by adding N pieces of excitation signals corresponding to N pieces of bands, said speech and music signal coder comprising:

differential signal calculating means for calculating a differential signal indicative of difference between a signal produced by adding a first through an (N−

1)-th coded decoding signal and the input signal; and

N-th coding means for generating a residual signal by driving an inverse filter of the linear prediction synthesis filter on the basis of the input signal in response the differential signal and for coding a component corresponding to an arbitrary band in the residual after orthogonal transformation of the component.

8. A speech and music signal coder comprising:

second input signal generating means for generating a second input signal by down-sampling a first input signal sampled at a first sampling frequency to a second sampling frequency;

first reproduction signal generating means for generating a first reproduction signal by driving a synthesis filter set with a first linear prediction coefficient calculated on the basis of the second input signal in response to an excitation signal;

second reproduction signal generating means for generating a second reproduction signal by up-sampling the first reproduction signal to the first sampling frequency;

third linear prediction coefficient calculating means for calculating a third linear prediction coefficient on the basis of a difference of the first linear prediction coefficient and a second linear prediction coefficient provided by converting a sampling frequency to the first sampling frequency;

residual signal generating means for calculating a fourth linear prediction coefficient on the basis of a sum of the second linear prediction coefficient and the third linear prediction coefficient and for generating a residual signal by driving an inverse filter set with the fourth linear prediction coefficient on the basis of a differential signal indicative of difference between the first input signal and the second reproduction signal; and

coding means for coding a component corresponding to an arbitrary band in the residual signal after orthogonal transformation of the component.

9. A speech and music signal decoder for generating a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal provided by adding an excitation signal corresponding to a first band and an excitation signal corresponding to a second band, said speech and music signal decoder comprising:

excitation signal generating means for generating the excitation signal corresponding to the second band by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation;

second reproduction signal generating means for generating a second reproduction signal by driving the linear prediction synthesis, filter in response to the excitation signal corresponding to the second band;

first reproduction signal generating means for generating a first reproduction signal by driving the linear prediction filter in response to the excitation signal corresponding to the first band; and

speech and music decoded signal generating means for generating speech and music decoded signal by adding the first reproduction signal and the second reproduction signal.

15. A speech and music signal decoder as claimed in claim 9, wherein a pitch prediction filter is used in generating the excitation signal corresponding to the first band.

10. A speech and music signal decoder for generating a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal provided by adding 3 pieces of excitation signals corresponding to a first through a third band, said speech and music signal decoder comprising:

first and second reproduction signal generating means for generating a first and a second reproduction signal by driving the linear prediction filter in response to the excitation signals corresponding to the first and the second bands;

third reproduction signal generating means for generating the excitation signal corresponding to the third band by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation, and for generating a third reproduction signal by driving the linear prediction synthesis filter in response to the excitation signal; and

speech and music decoded signal generating means for generating a speech and music decoded signal by adding the first through the third reproduction signals.

11. A speech and music signal decoder for generating a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal provided by adding N pieces of excitation signals corresponding to first through an N-th band, said speech and music signal decoder comprising:

N-th reproduction signal generating means for generating an excitation signal corresponding to the N-th band by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and for generating an N-th reproduction signal by driving the linear prediction synthesis filter in response to the excitation signal;

first through (N−

1)-th reproduction signal generating means for generating a first through an (N−

1)-th reproduction signal by driving the linear prediction filter in response to the excitation signals corresponding to the first through the (N−

1)-th bands; and

speech and music decoded signal generating means for generating a speech and music decoded signal by adding the first through the N-th reproduction signals.

12. A speech and music signal decoder for generating a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal provided by adding excitation signals corresponding to a first and a second band, said speech and music signal decoder comprising:

reproduction signal generating means for generating an excitation signal by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and for generating a second reproduction signal by driving a linear prediction synthesis filter by the excitation signal; and

speech and music decoded signal generating means for generating a speech and music decoded signal by adding the second reproduction signal and a first reproduction signal from first reproduction signal generating means.

13. A speech and music signal decoder for generating a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal provided by adding excitation signals corresponding to a first through a third band, said speech and music signal decoder comprising:

third reproduction signal generating means for generating the excitation signal by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and for generating a third reproduction signal by driving the linear prediction synthesis filter in response to the excitation signal; and

speech and music signal generating means for generating a speech and music signal by adding a first and a second reproduction signal respectively outputted from first and second reproduction signal generating means.

14. A speech and music signal decoder for generating a reproduction signal by driving a linear prediction synthesis filter in response to an excitation signal provided by adding N pieces of excitation signals corresponding to a first through an N-th band;

N-th reproduction signal generating means for generating the excitation signal by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and for generating an N-th reproduction signal by driving the linear prediction synthesis filter in response to the excitation signal; and

speech and music decoded signal generating means for generating a speech and music decoded signal by adding the N-th reproduction signal and a first through an (N−

1)-th reproduction signal.

16. A speech and music signal decoder comprising:

first reproduction signal generating means for up-sampling a signal provided by driving a first linear prediction synthesis filter in response to a first excitation signal corresponding to a first band to a first sampling frequency and for generating a reproduction signal;

second reproduction signal generating means for generating a second excitation signal corresponding to a second band by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and for generating a second reproduction signal by driving a second linear prediction synthesis filter in response to the second excitation signal; and

speech and music decoded signal by adding the first and the second reproduction signal.

17. A speech and music signal coding/decoding apparatus comprising:

a speech and music signal coder that produces a coded signal by driving a first linear prediction synthesis filter in response to a first excitation signal which is provided by adding a first signal corresponding to a first band of an input signal and a second signal corresponding to a second band of the input signal, said linear prediction synthesis filter being set with a linear prediction coefficient calculated on the basis of said input signal, said speech and music signal coder comprising;

a reproduction signal generating circuit producing a reproduction signal by driving the first linear prediction synthesis filter in response to the first signal corresponding to the first band of the input signal;

a residual signal generating circuit generating a residual signal by driving a linear prediction inverse filter in response to a differential signal indicative of a difference between the first input signal and the reproduction signal; and

a coding circuit coding a component corresponding to the residual signal after orthogonal transformation of the component; and

a speech and music signal decoder that decodes the coded signal of the signal coder by driving a second linear prediction synthesis filter in response to a second excitation signal provided by adding a first signal corresponding to a first band of the second excitation signal and a second signal corresponding to a second band of the second excitation signal, said speech and music signal decoder comprising;

an excitation signal generating circuit generating the second signal corresponding to the second band of the second excitation signal by subjecting a decoding signal and an orthogonal transformation coefficient to orthogonal inverse transformation;

a second reproduction signal generating circuit generating a second reproduction signal by driving the second linear prediction synthesis filter in response to the second excitation signal;

a third reproduction signal generating circuit generating a third reproduction signal by driving the second linear prediction synthesis filter in response to the first signal corresponding to the first band of the second excitation signal; and

a speech and music decoded signal generating circuit generating a speech and music decoded signal by adding the second reproduction signal and the third reproduction signal.

23. A speech and music signal coding/decoding apparatus as claimed in claim 17, wherein:

the speech and music signal coder further comprises a first pitch prediction filter that generates the first signal corresponding to the first band of the input signal; and

the speech and music signal decoder further comprises a second pitch prediction filter that generates the first signal corresponding to the first band of the second excitation signal.

18. A speech and music signal coding/decoding apparatus comprising:

a speech and music signal coder that produces a coded signal by driving a first linear prediction synthesis filter in response to a first excitation signal which is provided by adding 3 pieces of excitation signals corresponding to 3 pieces of bands, said first linear prediction synthesis filter being set with a linear prediction coefficient calculated on the basis of an input signal, said speech and music signal coder comprising;

a first reproduction signal generating circuit generating a first and a second reproduction signal by driving the first linear prediction synthesis filter in response to the excitation signals corresponding to a first one and a second one of the bands; and

a coding circuit generating a residual signal by driving a linear prediction inverse filter in response to a differential signal indicative of a difference between an added signal produced by adding the first and the second reproduction signals and the input signal and coding a component corresponding to a third one of the bands in the residual signal after orthogonal transformation of the component; and

a speech and music signal decoder that decodes the coded signal of the signal coder by driving a second linear prediction synthesis filter in response to a second excitation signal provided by adding 3 pieces of excitation signals corresponding to a first through a third band, said speech and music signal decoder comprising;

a second reproduction signal generating circuit generating a third and a fourth reproduction signal by driving the second linear prediction filter in response to the second excitation signals corresponding to the first and the second bands;

a third reproduction signal generating circuit generating the second excitation signal corresponding to the third band by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation, and generating a fifth reproduction signal by driving the second linear prediction synthesis filter in response to the second excitation signal; and

a speech and music decoded signal generating circuit generating a speech and music decoded signal by adding the third through the fifth reproduction signals.

19. A speech and music signal coding/decoding apparatus comprising:

a speech and music signal coder that produces a coded signal by driving a first linear prediction synthesis filter in response to a first excitation signal which is provided by adding N pieces of excitation signals corresponding to N pieces of bands of an input signal, said speech and music signal coder comprising;

a first reproduction signal generating circuit generating a first through an (N−

1)-th first reproduction signal by driving the first linear prediction synthesis filter in response to the first excitation signals corresponding to a first through an (N−

1)-th band; and

an N-th coding circuit generating a residual signal by driving a linear prediction inverse filter in response to a differential signal indicative of a difference between a signal produced by adding the first through the (N−

1)-th first reproduction signals and the input signal and coding a component corresponding to an N-th band in the residual signal after orthogonal transformation of the component; and

a speech and music signal decoder that decodes the coded signal of the signal coder by driving a second linear prediction synthesis filter in response to a second excitation signal provided by adding N pieces of excitation signals corresponding to first through an N-th band, said speech and music signal decoder comprising;

an N-th reproduction signal generating circuit generating a reproduction signal corresponding to the N-th band by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and generating an N-th reproduction signal by driving the second linear prediction synthesis filter in response to the second excitation signal;

a first through (N−

1)-th second reproduction signal generating circuit generating a first through an (N−

1)-th second reproduction signal by driving the second linear prediction synthesis filter in response to the second excitation signals corresponding to the first through the (N−

1)-th bands; and

a speech and music decoded signal generating circuit generating a speech and music decoded signal by adding the first through the (N−

1)-th second reproduction signals.

20. A speech and music signal coding/decoding apparatus comprising:

a speech and music signal coder that produces a coded signal by driving a first linear prediction synthesis filter in response to a first excitation signal which is provided by adding 2 pieces of excitation signals corresponding to 2 pieces of bands, said speech and music signal coder comprising;

a difference circuit calculating a difference of a first coded decoding signal and an input signal; and

a coding circuit generating a residual signal by driving a linear prediction inverse filter in response to the differential signal and coding a component corresponding to an arbitrary one of the bands in the residual signal after subjecting the component to orthogonal transformation; and

a speech and music signal decoder that decodes the coded signal of the signal coder by driving a second linear prediction synthesis filter in response to a second excitation signal provided by adding excitation signals corresponding to a first and a second band, said speech and music signal decoder comprising;

a reproduction signal generating circuit generating a first reproduction signal by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and generating a second reproduction signal by driving a third linear prediction synthesis filter by the first reproduction signal; and

a speech and music decoded signal generating circuit generating a speech and music decoded signal by adding the second reproduction signal and the first reproduction signal from reproduction signal generating circuit.

21. A speech and music signal coding/decoding apparatus comprising:

a speech and music signal coder that produces a coded signal by driving a first linear prediction synthesis filter in response to an excitation signal provided by adding 3 pieces of excitation signals corresponding to 3 pieces of bands of an input signal, said speech and music signal coder comprising;

a difference circuit calculating a differential signal indicative of difference between a signal produced by adding a first and a second coded decoding signal and the input signal; and

a coding circuit generating a residual signal by driving a linear prediction inverse filter calculated on the basis of the input signal and the differential signal, and coding a component corresponding to an arbitrary band in the residual signal after orthogonal transformation of the component; and

a speech and music signal decoder that decodes the coded signal of the signal coder by driving a second linear prediction synthesis filter in response to a second excitation provided by adding excitation signals corresponding to a first through a third band, said speech and music signal decoder comprising;

a first reproduction signal generating circuit generating a first reproduction signal by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation;

a second reproduction signal generating circuit generating a second reproduction signal by driving the second linear prediction synthesis filter in response to the first reproduction signal; and

a speech and music signal generating circuit generating a speech and music signal by adding the first and a second reproduction signals generated by the first and second reproduction signal generating circuit.

22. A speech and music signal coding/decoding apparatus comprising:

a speech and music signal coder that produces a coded signal by driving a first linear prediction synthesis filter in response to a first excitation signal which is provided by adding N pieces of excitation signals corresponding to N pieces of bands of an input signal, said speech and music signal coder comprising;

a differential signal calculating circuit calculating a differential signal indicative of difference between a signal produced by adding a first through an (N−

1)-th coded decoding signal and the input signal; and

an N-th coding circuit generating a residual signal by driving an inverse filter of the first linear prediction synthesis filter on the basis of the input signal in response the differential signal and coding a component corresponding to an arbitrary band in the residual signal after orthogonal transformation of the component; and

a speech and music signal decoder that decodes the coded signal of the signal coder by driving a second linear prediction synthesis filter in response to a second excitation signal provided by adding N pieces of excitation signals corresponding to a first through an N-th band;

said speech and music signal decoder comprising;

an N-th reproduction signal generating circuit generating a first reproduction signal by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and generating an N-th reproduction signal by driving the second linear prediction synthesis filter in response to the first reproduction signal; and

a speech and music decoded signal generating circuit generating a speech and music decoded signal by adding the N-th reproduction signal and a first through an (N−

1)-th reproduction signal.

24. A speech and music signal coding/decoding apparatus comprising:

a speech and music signal coder comprising;

an input signal generating circuit generating an input signal by down-sampling a sampling signal sampled at a first sampling frequency to a second sampling frequency;

a first reproduction signal generating circuit generating a first reproduction signal by driving a synthesis filter set with a first linear prediction coefficient calculated on the basis of the input signal in response to a first excitation signal;

a second reproduction signal generating circuit generating a second reproduction signal by up-sampling the first reproduction signal to the first sampling frequency;

a linear prediction coefficient calculating circuit calculating a first linear prediction coefficient on the basis of a difference between a second linear prediction coefficient and a third linear prediction coefficient provided by converting a sampling frequency to the first sampling frequency;

a residual signal generating circuit calculating a fourth linear prediction coefficient on the basis of a sum of the third linear prediction coefficient and the first linear prediction coefficient and generating a residual signal by driving an inverse filter set with a fourth linear prediction coefficient calculated on the basis of a differential signal indicative of difference between the sampling signal and the second reproduction signal; and

a coding circuit coding a component corresponding to an arbitrary band in the residual signal after orthogonal transformation of the component; and

a speech and music signal decoder comprising;

a third reproduction signal generating circuit up-sampling a signal provided by driving a second linear prediction synthesis filter in response to a second excitation signal corresponding to a first band to a third sampling frequency and generating a third reproduction signal;

a fourth reproduction signal generating circuit generating a second excitation signal corresponding to a second band by subjecting a decoded orthogonal transformation coefficient to orthogonal inverse transformation and generating a fourth reproduction signal by driving a third linear prediction synthesis filter in response to the second excitation signal; and

a speech and music decoded signal generating circuit generating a speech and music decoded signal by adding the third and the fourth reproduction signal.