Claims
- 1. A method of synthesizing speech, comprising the steps of:
- receiving a pitch lag;
- retrieving an adaptive codebook excitation signal from an adaptive codebook using the pitch lag;
- receiving an adaptive codebook gain;
- scaling the adaptive codebook excitation signal using the adaptive codebook gain to generate a scaled adaptive codebook excitation signal;
- receiving a fixed excitation signal;
- receiving a fixed excitation gain;
- scaling the fixed excitation signal using the fixed excitation gain to generate a scaled fixed excitation signal;
- combining the scaled adaptive codebook excitation signal and the scaled fixed excitation signal to generate an excitation signal having a first word length;
- receiving an overall gain signal of the excitation signal; and
- scaling the excitation signal using the overall gain signal to generate a scaled excitation signal having a second word length greater than the first word length.
- 2. The method of claim 1, wherein the first word length comprises eight (8) bits and the second word length comprises sixteen (16) bits.
- 3. The method of claim 1, wherein the adaptive codebook excitation signal, adaptive codebook gain, fixed excitation signal, and fixed excitation gain comprise the first word length.
- 4. The method of claim 3, wherein the first word length comprises eight (8) bits and the second word length comprises sixteen (16) bits.
- 5. The method of claim 3, wherein the scaled adaptive codebook excitation signal and the scaled fixed excitation signal comprise the first word length.
- 6. The method of claim 5, wherein the first word length comprises eight (8) bits and the second word length comprises sixteen (16) bits.
- 7. The method of claim 1, further comprising the steps of:
- receiving an LPC coefficients signal; and
- synthesizing the scaled excitation signal using the LPC coefficients signal to generate a synthesized signal.
- 8. The method of claim 1, wherein the LPC coefficients are reflection coefficients.
- 9. The method of claim 7, wherein the LPC coefficients signal and the synthesized signal comprise the second word length.
- 10. The method of claim 9, wherein the first word length comprises eight (8) bits and the second word length comprises sixteen (16) bits.
- 11. A code-excited linear prediction (CELP) synthesizer, comprising:
- an excitation node operable to receive an excitation signal having a first word length;
- an overall gain node operable to receive an overall gain signal of the excitation signal; and
- the overall gain node operable to scale the excitation signal using the overall gain signal to generate a scaled excitation signal having a second word length greater than the first word length.
- 12. The CELP synthesizer of claim 11, wherein the first word length comprises eight (8) bits and the second word length comprises sixteen (16) bits.
- 13. The CELP synthesizer of claim 11, further comprising:
- an adaptive codebook excitation node operable to receive an adaptive codebook excitation signal;
- an adaptive codebook gain node operable to receive an adaptive codebook gain and to scale the adaptive codebook excitation signal using the adaptive codebook gain to generate a scaled adaptive codebook excitation signal;
- a fixed excitation node operable to receive a fixed excitation signal;
- a fixed excitation gain node operable to receive a fixed excitation gain and to scale the fixed excitation signal using the fixed excitation gain to generate a scaled fixed excitation signal; and
- an adder operable to combine the scaled adaptive codebook excitation signal and the scaled fixed excitation signal to generate the excitation signal.
- 14. The CELP synthesizer of claim 13, wherein the adaptive codebook excitation signal, adaptive excitation gain, scaled adaptive codebook excitation signal, fixed excitation signal, fixed excitation gain, and scaled fixed excitation signal comprise the first word length.
- 15. The CELP synthesizer of claim 13, further comprising:
- an adaptive codebook, comprising:
- a plurality of entries each containing previous excitation samples;
- a pointer operable to identifying an entry containing an oldest previous excitation sample;
- the adaptive codebook operable to overwrite the identified entry with a current excitation sample; and
- the adaptive codebook operable to shift the pointer to identify another entry containing a next oldest previous excitation sample.
- 16. The CELP synthesizer of claim 11, further comprising:
- a linear predictive coding (LPC) filter operable to receive a reflection coefficients signal;
- the LPC filter operable to receive the scaled excitation signal; and
- the LPC filter operable to synthesize the scaled excitation signal using the reflection coefficients to generate a synthesized signal.
Parent Case Info
This application claims priority under 35 USC .sctn.119(e) (1) of provisional application No. 60/034,169 filed Jan. 02, 1997.
Non-Patent Literature Citations (1)
Entry |
Wilfrid LeBlanc, Christine Liu amd Vishu Viswanathan, "An Enhanced Full Rate Speech Coder for Digital Cellular Applications," IEEE 1996, pp. 1-4. |