ADAPTIVE AUDIO CODEC SYSTEM, METHOD AND ARTICLE

• US 20170330572A1
• Filed: 05/10/2016
• Published: 11/16/2017
• Est. Priority Date: 05/10/2016
• Status: Active Grant

• Current Assignee: Immersion Networks
• Original Assignee: Immersion Services, LLC
• Inventors: Johnston, James D., White, Stephen
• Granted Patent: US 10,756,755 B2
• Time in Patent Office: Days
• CPC Class Codes: G10L 19/0017 Lossless audio signal coding; Perfect reconstruction of coded audio signal by transmission of coding error G10L19/24 takes precedence
• CPC Class Codes: G10L 19/04 using predictive techniques
• CPC Class Codes: H03M 7/3046 adaptive, e.g. adaptive differential pulse code modulation [ADPCM]

Abstract

An encoder generates quantized signal words based on a difference signal. The encoder includes an adaptive quantizer. A step size applied by the adaptive quantizer is generated in a feedback loop and based on a loading factor and quantized signal words generated by the adaptive quantizer. The encoder includes coding circuitry which generates code words based on quantized signal words generated by the adaptive quantizer. The coding circuitry generates an escape code in response to a quantized signal word not being associated with a corresponding coding code word.

Claims

1. An apparatus, comprising:

an encoder configured to generate quantized signal words based on a difference signal and including;

an adaptive quantizer, wherein a step size applied by the adaptive quantizer is generated in a feedback loop and based on a loading factor and quantized signal words generated by the adaptive quantizer; and

a decoder configured to generate a prediction signal and having an inverse quantizer and a predictor circuit; and

coding circuitry configured to generate code words based on quantized signal words generated by the adaptive quantizer, wherein the coding circuitry is configured to generate an escape code in response to a quantized signal word not being associated with a corresponding coding code word.

2. The apparatus of claim 1 wherein the coding circuitry is configured to generate an escape code in response to at least one of:

an end of a signal channel; and

an end of a signal to be encoded.

3. The apparatus of claim 1 wherein the coding circuitry is configured to use Huffman coding to generate the code words.

4. The apparatus of claim 1 wherein the feedback loop is configured to generate the step size according to:

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

5. The apparatus of claim 1 wherein the feedback loop is configured to generate the step size according to:

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

6. A method, comprising:

encoding a signal, the encoding including;

generating quantized signal words based on a difference signal, wherein a quantization step size is determined in a feedback loop based on a loading factor and the generated quantized signal words;

generating a prediction signal based on the generated quantized signal words;

generating the difference signal based on the signal to be encoded and the prediction signal; and

generating code words based on the quantized signal words, wherein the generating code words includes generating an escape code in response to a quantized signal word not being associated with a corresponding coding code word.

7. The method of claim 6, comprising:

generating an escape code in response to at least one of;

an end of a signal channel of the signal to be encoded; and

an end of the signal to be encoded.

8. The method of claim 6, comprising:

using Huffman coding to generate the code words.

9. The method of claim 6, comprising:

determining the quantization step size according to;

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

10. The method of claim 6, comprising:

determining the quantization step size according to;

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

11. A non-transitory computer-readable medium having contents which configure signal processing circuitry to encode a signal, the encoding comprising:

generating quantized signal words based on a difference signal, wherein a quantization step size is determined in a feedback loop based on a loading factor and the generated quantized signal words;

generating a prediction signal based on the generated quantized signal words;

generating the difference signal based on the signal to be encoded and the prediction signal; and

generating code words based on the quantized signal words, wherein the generating code words includes generating an escape code in response to a quantized signal word not being associated with a corresponding coding code word.

12. The non-transitory computer-readable medium of claim 11 wherein the encoding comprises:

generating an escape code in response to at least one of;

an end of a signal channel of the signal to be encoded; and

an end of the signal to be encoded.

13. The non-transitory computer-readable medium of claim 11 wherein the encoding comprises:

using Huffman coding to generate the code words.

14. The non-transitory computer-readable medium of claim 11 wherein the encoding comprises:

determining the quantization step size according to;

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

15. The non-transitory computer-readable medium of claim 11 wherein the encoding comprises:

determining the quantization step size according to;

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

16. A system, comprising:

means for generating quantized signal words based on a difference signal, wherein a quantization step size is determined based on a loading factor and the generated quantized signal words;

means for generating a prediction signal based on the generated quantized signal words;

means for generating the difference signal based on the signal to be encoded and the prediction signal; and

means for generating code words based on the quantized signal words, wherein the generating code words includes generating an escape code in response to a quantized signal word not being associated with a corresponding coding code word.

17. The system of claim 16 wherein the means for generating code words generates an escape code in response to at least one of:

an end of a signal channel of the signal to be encoded; and

an end of the signal to be encoded.

18. The system of claim 16 wherein the means for generating code words uses Huffman coding to generate code words.

19. The system of claim 16 wherein the means for generating quantized signal words determines the quantization step size according to:

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

20. The system of claim 16 wherein the means for generating quantized signal words determines the quantization step size according to:

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

21. The system of claim 16, comprising:

means for decoding code words generated by the means for generating code words.

22. An apparatus, comprising:

decoding circuitry configured to generate quantized signal words based on code words included in a bit stream, wherein the decoding circuitry is configured to respond to an escape code in the bit stream indicative of a quantized signal word being included in the bit stream;

an inverse quantizer, wherein a step size applied by the inverse quantizer is generated in a feedback loop and based on a loading factor and quantized signal words received by the inverse quantizer from the decoding circuitry; and

a predictor circuit coupled to the inverse quantizer.

23. The apparatus of claim 22 wherein the coding circuitry is configured to respond to at least one of:

an escape code indicating an end of a signal channel; and

an escape code indicating an end of a signal to be encoded.

24. The apparatus of claim 22 wherein the coding circuitry is configured to use Huffman coding to generate the quantized signal words.

25. The apparatus of claim 22 wherein the feedback loop is configured to generate the step size according to:

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

26. The apparatus of claim 22 wherein the feedback loop is configured to generate the step size according to:

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

27. A method, comprising:

generating quantized signal words based on code words included in a bit stream, the generating quantized signal words including responding to an escape code in the bit stream indicative of a quantized signal word being included in the bit stream;

inverse quantizing the generated quantized signal words, wherein a step size applied in the inverse quantizing is determined in a feedback loop and based on a loading factor and the generated quantized signal words; and

generating a prediction signal based on the generated quantized signal words.

28. The method of claim 27 wherein the generating quantized signal words includes responding to at least one of:

an escape code indicating an end of a signal channel; and

an escape code indicating an end of a signal to be encoded.

29. The method of claim 27 wherein the generating quantized signal words includes using Huffman coding.

30. The method of claim 27 wherein the feedback loop determines the step size according to:

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

31. The method of claim 27 wherein the feedback loop determines the step size according to:

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

32. A non-transitory computer-readable medium having contents which configure signal processing circuitry to decode a signal, the decoding including:

generating quantized signal words based on code words included in a bit stream, the generating quantized signal words including responding to an escape code in the bit stream indicative of a quantized signal word being included in the bit stream;

inverse quantizing the generated quantized signal words, wherein a step size applied in the inverse quantizing is determined in a feedback loop and based on a loading factor and the generated quantized signal words; and

generating a prediction signal based on the generated quantized signal words.

33. The non-transitory computer-readable medium of claim 32 wherein the generating quantized signal words includes responding to at least one of:

an escape code indicating an end of a signal channel; and

an escape code indicating an end of a signal to be encoded.

34. The non-transitory computer-readable medium of claim 32 wherein the generating quantized signal words includes using Huffman coding.

35. The non-transitory computer-readable medium of claim 32 wherein the feedback loop determines the step size according to:

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

36. The non-transitory computer-readable medium of claim 32 wherein the feedback loop determines the step size according to:

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

37. A system, comprising:

means for generating quantized signal words based on code words included in a bit stream, the generating quantized signal words including responding to an escape code in the bit stream indicative of a quantized signal word being included in the bit stream;

means for inverse quantizing the generated quantized signal words, wherein a step size applied in the inverse quantizing is determined in a feedback loop and based on a loading factor and the generated quantized signal words; and

means for generating a prediction signal based on the generated quantized signal words.

38. The system of claim 37 wherein the generating quantized signal words includes responding to at least one of:

an escape code indicating an end of a signal channel; and

an escape code indicating an end of a signal to be encoded.

39. The system of claim 37 wherein the generating quantized signal words includes using Huffman coding.

40. The system of claim 37 wherein the feedback loop determines the step size according to:

d_n+1=β

d_n+m(c_n/L_factor),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

41. The system of claim 37 wherein the feedback loop determines the step size according to:

d_n+1=max(β

d_n+m(c_n/L_factor),d_min),

where c_n is a current quantized signal word, d_n corresponds to a current step size in a log domain, L_factor is the loading factor, m(c_n/L_factor) is a log multiplier selected based on the current quantized signal c_n and the loading factor L_factor, β

is a leakage coefficient, d_min is a threshold step size in the log domain, and d_n+1 corresponds to a step size in the log domain to be applied to a next quantized signal word c_n+1.

42. The system of claim 37, comprising:

means for generating a decoded signal based on inverse quantized signal words and the prediction signal.