Coding of a speech or music signal with quantization of harmonics components specifically and then residue components

• US 5,806,024 A
• Filed: 12/23/1996
• Issued: 09/08/1998
• Est. Priority Date: 12/23/1995
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ozawa, Kazunori
• Primary Examiner(s): Hudspeth, David R.
• Assistant Examiner(s): Chawan, Vijay B.
• Application Number:
  US08/773,523
• Time in Patent Office: 624 Days
• Field of Search: 704/222, 704/207, 704/223, 704/225, 704/204, 704/206, 704/230, 704/239, 704/218, 704/219, 704/221, 704/216
• US Class Current: 704/222
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/10 the excitation function being a multipulse excitation

Abstract

Harmonics coefficients are estimated in primary coefficients of an orthogonal transform of a speech or a music input signal by using a pitch frequency extracted from the input signal and are quantized into a harmonics code vector. Residue coefficients are calculated by removing the harmonics coefficients from the primary coefficients and quantized into residue code vectors and gain code vectors. It is possible to search harmonics excitation pulses at the harmonics locations for harmonics quantization into the harmonics code vector. On the other hand, it is possible to estimate the harmonics coefficients or excitation pulses by using quantized LSP parameters and to calculate secondary coefficients for use in weighting the harmonics quantization and residue quantization and, if applicable, in excitation pulse search.

Claims

1. A signal encoding method comprising the steps of:

calculating an orthogonal transform of an input signal to produce orthogonal transform coefficients of said orthogonal transform;

extracting a pitch frequency from said input signal;

estimating harmonics locations on said orthogonal transform coefficients by using said pitch frequency to produce harmonics coefficients at said harmonics locations;

quantizing said harmonics coefficients jointly as a representative coefficient into a harmonics code vector representative of a quantized harmonics coefficient; and

quantizing residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said orthogonal transform coefficients;

whereby said input signal is encoded into an output signal comprising a pitch interval of said pitch frequency and indexes indicative of said harmonics code vector, said residue code vectors, and said gain code vectors.

2. A signal encoding method comprising the steps of:

calculating an orthogonal transform of an input signal to produce orthogonal transform coefficients of said orthogonal transform;

extracting a pitch frequency from said input signal;

searching in said input signal a first pulse sequence of primary excitation pulses by repeatedly using said pitch frequency and a second pulse sequence of secondary excitation pulses without using said pitch frequency;

quantizing the excitation pulses of a selected one of said first and said second pulse sequences jointly as a representative pulse into a pulse code vector representative of a quantized representative coefficient; and

quantizing residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said orthogonal transform coefficients;

whereby said input signal is encoded into an output signal comprising a pitch interval of said pitch frequency and indexes indicative of pulse positions of said primary and said secondary excitation pulses, said pulse code vector, said residue code vectors, and said gain code vectors.

3. A signal encoding device comprising:

an orthogonal transform circuit responsive to a device input signal for calculating an orthogonal transform of said device input signal to produce orthogonal transform coefficients of said orthogonal transform;

a pitch extractor for extracting a pitch frequency from said device input signal;

a harmonics estimating circuit responsive to said pitch frequency for estimating harmonics locations in said orthogonal transform coefficients to produce harmonics coefficients at said harmonics locations;

a harmonics quantizer for quantizing said harmonics coefficients jointly as a representative coefficient into a harmonics code vector representative of a quantized representative coefficient; and

a residue quantizer for quantizing residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said orthogonal transform coefficients;

whereby said device input signal is encoded into a device output signal comprising a pitch interval of said pitch frequency and indexes indicative of said harmonics code vector, said residue code vectors, and said gain code vectors.

4. A signal encoding device as claimed in claim 3, wherein said harmonics quantizer quantizes amplitudes of said harmonics coefficients.

5. A signal encoding device as claimed in claim 3, wherein said harmonics quantizer quantizes polarities of said harmonics coefficients.

6. A signal encoding device as claimed in claim 3, wherein said pitch extractor extracts said pitch frequency from each frame of said device input signal.

7. A signal encoding device as claimed in claim 3, wherein said pitch extractor extracts said pitch frequency from orthogonal transform coefficients produced from each frame of said device input signal.

8. A signal encoding device comprising:

a spectral parameter quantizer for quantizing spectral parameters of a device input signal into quantized parameters and for converting said quantized parameters into linear prediction coefficients;

an inverse filter responsive to said linear prediction coefficients for producing an inverse filtered signal;

a first orthogonal transform circuit responsive to said inverse filtered signal for calculating a first orthogonal transform of said device input signal to produce primary coefficients of said first orthogonal transform;

a pitch extractor for extracting a pitch frequency from said device input signal;

a harmonics estimating circuit responsive to said pitch frequency for estimating harmonics locations on said primary coefficients to produce harmonics coefficients at said harmonics locations;

an impulse response calculating circuit for calculating auditorily weighted impulse responses of said linear prediction coefficients to produce an impulse response signal representative of said auditorily weighted impulse responses;

a second orthogonal transform circuit responsive to said impulse response signal for calculating a second orthogonal transform of said impulse response signal to produce secondary coefficients of said second orthogonal transform;

a harmonics quantizer for quantizing said harmonics coefficients jointly as a representative coefficient by using said secondary coefficients into a harmonics code vector representative of a quantized representative coefficient; and

a residue quantizer for quantizing residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said primary coefficients;

whereby said device input signal is encoded into a device output signal comprising indexes indicative of said quantized parameters, said harmonics code vector, said residue code vectors, and said gain code vectors.

9. A signal encoding device as claimed in claim 8, wherein said harmonics quantizer quantizes amplitudes of said primary coefficients.

10. A signal encoding device as claimed in claim 8, wherein said harmonics quantizer quantizes polarities of said primary coefficients.

11. A signal encoding device as claimed in claim 8, wherein said pitch extractor extracts said pitch frequency from each frame of said device input signal.

12. A signal encoding device as claimed in claim 8, wherein said pitch extractor extracts said pitch frequency from the primary coefficients produced from each frame of said device input signal.

13. A signal encoding device comprising:

an orthogonal transform circuit responsive to a device input signal for calculating an input orthogonal transform of said device input signal to produce orthogonal transform coefficients of said orthogonal transform;

a pitch extractor for extracting a pitch frequency from said device input signal;

a pulse searching circuit for repeatedly searching in said device input signal a first pulse sequence of primary excitation pulses by using said pitch frequency and a second pulse sequence of secondary excitation pulses without using said pitch frequency;

a selector for selecting one of said first and said second pulse sequences as a selected sequence of selected excitation pulses that better represents said orthogonal transform coefficients than the other of said first and said second pulse sequences;

a harmonics quantizer for quantizing said selected excitation pulses jointly as a representative pulse into a pulse code vector representative of a quantized representative coefficient; and

a residue quantizer for quantizing residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said orthogonal transform coefficients;

whereby said device input signal is encoded into a device output signal comprising a pitch interval of said pitch frequency and indexes indicative of pulse positions of said selected excitation pulses, said pulse code vector, said residue code vectors, and said gain code vectors.

14. A signal encoding device as claimed in claim 13, wherein said harmonics quantizer quantizes amplitudes of said selected excitation pulses.

15. A signal encoding device as claimed in claim 13, wherein said harmonics quantizer quantizes polarities of said selected excitation pulses.

16. A signal encoding device as claimed in claim 13, wherein said pitch extractor extracts said pitch frequency from each frame of said device input signal.

17. A signal encoding device as claimed in claim 13, wherein said pitch extractor extracts said pitch frequency from the input orthogonal transform coefficients produced from each frame of said device input signal.

18. A signal encoding device comprising:

an orthogonal transform circuit responsive to a device input signal for calculating an input orthogonal transform of said device input signal to produce input orthogonal transform coefficients of said input orthogonal transform;

a pitch extracting circuit for extracting a pitch frequency from each of successive frames of said device input signal and for discriminating said successive frames between a voiced and an unvoiced frame;

a pulse searching circuit for repeatedly searching in said voiced frame a voiced frame pulse sequence of primary excitation pulses by using said pitch frequency and in said unvoiced frame an unvoiced frame pulse sequence of secondary excitation pulses without using said pitch frequency;

a harmonics quantizer for quantizing said primary excitation pulses jointly as a representative pulse into a pulse code vector representative of a quantized representative coefficient; and

a residue quantizer for quantizing residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said orthogonal transform coefficients;

whereby said device input signal is encoded into a device output signal comprising a pitch internal of said pitch frequency, information separately indicative of said voiced and said unvoiced frames, and indexes indicative of pulse positions of said primary and said secondary excitation pulses, said pulse code vector, said residue code vectors, and said gain code vectors.

19. A signal encoding device comprising:

a spectral parameter quantizing circuit for quantizing spectral parameters of a device input signal into quantized parameters and for converting said quantized parameters into linear prediction coefficients;

an inverse filter responsive to said linear prediction coefficients for producing an inverse filtered signal;

a first orthogonal transform circuit responsive to said inverse filtered signal for calculating a first orthogonal transform of said device input signal to produce primary coefficients of said first orthogonal transform;

a pitch extractor for extracting a pitch frequency from said device input signal;

an impulse response calculating circuit for calculating auditorily weighted impulse responses of said linear prediction coefficients to produce an impulse response signal representative of said auditorily weighted impulse responses;

a second orthogonal transform circuit responsive to said impulse response signal for calculating a second orthogonal transform of said impulse response signal to produce secondary coefficients of said second orthogonal transform;

a pulse searching circuit for repeatedly searching in said device input signal by using said secondary coefficients a first pulse sequence of primary excitation pulses by using said pitch frequency and a second pulse sequence of secondary excitation pulses without using said pitch frequency;

a selector for selecting one of said first and said second pulse sequences as a selected sequence of selected excitation pulses that better represents said first orthogonal transform than the other of said first and said second pulse sequences;

a harmonics quantizer for quantizing by using said second coefficients said selected excitation pulses jointly as a representative pulse into a pulse code vector representative of a quantized representative coefficient; and

a residue quantizer for quantizing by using said secondary coefficients residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said primary coefficients;

whereby said device input signal is encoded into a device output signal comprising indexes indicative of said quantized parameters, pulse positions of said primary and said secondary excitation pulses, said pulse code vector, said residue code vectors, and said gain code vectors.

20. A signal encoding device as claimed in claim 19, wherein said harmonics quantizer quantizes amplitudes of said selected excitation pulses.

21. A signal encoding device as claimed in claim 19, wherein said harmonics quantizer quantizes polarities of said selected excitation pulses.

22. A signal encoding device as claimed in claim 19, wherein said pitch extractor extracts said pitch frequency from each frame of said device input signal.

23. A signal encoding device as claimed in claim 19, wherein said pitch extractor extracts said pitch frequency from the primary coefficients produced from each frame of said device input signal.

24. A signal encoding device comprising:

a spectral parameter quantizing circuit for quantizing spectral parameters of an input signal into quantized parameters and for converting said quantized parameters into linear prediction coefficients;

an inverse filter responsive to said linear prediction coefficients for producing an inverse filtered signal;

a first orthogonal transform circuit responsive to said inverse filtered signal for calculating a first orthogonal transform of said device input signal to produce primary coefficients of said first orthogonal transform;

a pitch extracting circuit for extracting a pitch frequency from each of successive frames of said device input signal and for discriminating said successive frames between a voiced and an unvoiced frame;

an impulse response calculating circuit for calculating auditorily weighted impulse responses of said linear prediction coefficients to produce an impulse response signal representative of said auditorily weighted impulse responses;

a second orthogonal transform circuit responsive to said impulse response signal for calculating a second orthogonal transform of said impulse response signal to produce secondary coefficients of said second orthogonal transform;

a pulse searching circuit for repeatedly searching by using said secondary coefficients in said voiced frame a voiced frame pulse sequence of primary excitation pulses by using said pitch frequency and in said unvoiced frame and unvoiced frame pulse sequence of secondary excitation pulses without using said pitch frequency;

a harmonics quantizer for quantizing by using said secondary coefficients said primary excitation pulses jointly as a representative pulse into a pulse code vector representative of a quantized representative coefficient; and

a residue quantizer for quantizing by using said secondary coefficients residue coefficients into residue code vectors and gain code vectors, said residue coefficients being given by removing said quantized representative coefficient from said primary coefficients;

whereby said device input signal is encoded into a device output signal comprising information separately indicative of said voiced and said unvoiced frames and indexes indicative of said quantized parameters, pulse positions of said primary and said secondary excitation pulses, said pulse code vector, said residue code vectors, and said gain code vectors.