Scalable audio coding/decoding method and apparatus

• US 6,122,618 A
• Filed: 11/26/1997
• Issued: 09/19/2000
• Est. Priority Date: 04/02/1997
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Sung-hee
• Primary Examiner(s): Hudspeth, David R.
• Assistant Examiner(s): Azad, Abul K.
• Application Number:
  US08/978,877
• Time in Patent Office: 1,028 Days
• Field of Search: 704/222, 704/229, 704/230, 704/500, 704/501, 704/205, 704/209, 704/504
• US Class Current: 704/500
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/035 Scalar quantisation
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
• CPC Class Codes: H04B 1/665 using psychoacoustic properties of the ear, e.g. masking effect
• CPC Class Codes: H04N 19/184 the unit being bits, e.g. of the compressed video stream
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

A scalable audio coding/decoding method and apparatus are provided. The coding method includes the steps of (a) signal-processing input audio signals and quantizing the same for each predetermined coding band, (b) coding the quantized data corresponding to the base layer within a predetermined layer size, (c) coding the quantized data corresponding to the next enhancement layer of the coded base layer and the remaining quantized data uncoded and belonging to the enhancement layer, within a predetermined layer size, and (d) sequentially performing the layer coding steps for all layers, wherein the steps (b), (c) and (d) each include the steps of (e) representing the quantized data corresponding to a layer to be coded by digits of a predetermined same number, and (f) coding the most significant digit sequences composed of most significant digits of the magnitude data composing the represented digital data. The method can accommodate various users'"'"' request and transmission channels, and the complexity of the encoder and decoder can be reduced. Also, according to the performance of decoders or bandwidth/congestion of transmission channels or by users'"'"' request, the bitrate or complexity can be controlled.

Claims

1. A scalable audio coding method for coding audio signals into a layered datastream having a base layer and enhancement layers of a predetermined number, comprising the steps of:

(a) signal-processing input audio signals and quantizing the same for each predetermined coding band;

(b) coding the quantized date corresponding to the base layer within a predetermined layer size;

(c) coding the quantized data corresponding to the next enhancement layer of the coded base layer and the remaining quantized data uncoded and belonging to the coded layer, within a predetermined layer size; and

(d) sequentially performing the layer coding steps for all layers, wherein the steps (b), (c) and (d) each comprise the steps of;

(e) representing the quantized data corresponding to a layer to be coded by digits of a predetermined number; and

(f) coding the most significant digit sequences of most significant digits of the magnitude data of said quantized signal-processing input audio signals.

2. The scalable audio coding method according to claim 1, wherein the steps (e) and (f) are performed sequentially from low frequency to high frequency.

3. The scalable audio coding method according to claim 1, wherein the coding steps (b), (c) and (d) are performed on side information having at least quantization step size information and quantization bit information allotted to each band, by a predetermined coding method.

4. The scalable audio coding method according to claim 1 or 3, wherein the digits in the steps (e) and (f) are bits.

5. The scalable audio coding method according to claim 4, wherein the coding in the step (f) is performed by coupling bits composing the bit sequences into units of bits of a predetermined number.

6. The scalable audio coding method according to claim 4, wherein the predetermined coding method is lossless coding.

7. The scalable audio coding method according to claim 5, wherein the predetermined coding method is lossless coding.

8. The scalable audio coding method according to claim 6 or 7, wherein the lossless coding is Huffman coding.

9. The scalable audio coding method according to claim 6 or 7, wherein the lossless coding is Arithmetic coding.

10. The scalable audio coding method according to claim 1, wherein, when the quantized data is composed of sign data and magnitude data, the step (f) comprises the steps of:

i) coding the most significant digit sequences composed of most significant digits of the magnitude data composing the represented digital data by a predetermined coding method;

ii) coding sign data corresponding to non-zero data among the coded most significant digit sequences;

iii) coding the most significant digit sequences among uncoded magnitude data of the digital data by a predetermined coding method;

iv) coding uncoded sign data among the sign data corresponding to non-zero magnitude data among digit sequences coded in the step (iii); and

v) performing the steps (iii) and (iv) on the respective digits of the digital data.

11. The scalable audio coding method according to claim 10, wherein the step (e) is to represent the digital data as binary data having bits of the same number, and the digits are bits.

12. The scalable audio coding method according to claim 10, wherein the coding steps are performed by coupling bits composing the respective bit sequences for the magnitude data and sign data, into units of bits of a predetermined number.

13. The scalable audio coding method according to claim 11 or 12, wherein the predetermined coding method is Arithmetic coding.

14. The scalable audio coding method according to claim 10, wherein the coding steps (b), (c) and (d) are performed on side information having at least quantization step size information and quantization bit information allotted to each band, by a predetermined coding method.

15. The scalable audio coding method according to claim 1 or 10, wherein quantization is performed by the steps of:

converting the input audio signals of a temporal domain into signals of a frequency domain;

coupling the converted signals as signals of predetermined subbands by time/frequency mapping and calculating a masking threshold at each subband; and

quantizing the signals for each predetermined coding band so that quantization noise of each band is smaller than the masking threshold.

16. A scalable audio coding method for coding audio signals into a layered datastream having a base layer and enhancement layers of a predetermined number, comprising the steps of:

(a) signal-processing input audio signals and quantizing the same for each predetermined coding band;

(b) coding the quantized data of a first range of frequencies corresponding to the base layer within a predetermined layer size;

(c) coding the quantized data of a second range of frequencies corresponding to the next enhancement layer within a predetermined layer size; and

(d) sequentially performing the layer coding steps for all layers, wherein the steps (b), (c) and (d) each comprise the steps of;

(e) representing the quantized data corresponding to a layer to be coded by digits of a predetermined same number; and

(f) coding the most significant digit sequences composed of most significant digits of the magnitude data composing the represented digital data.

17. The scalable audio coding method according to claim 16, said second range of frequencies includes frequencies different from said first range of frequencies wherein the most significant digits of the quantized data of said frequencies different from said first range of frequencies are coded before coding next significant digits of the quantized data belonging to the corresponding enhancement layer.

18. The scalable audio coding method according to claim 17, wherein the steps (e) and (i) are performed sequentially in the order of lower frequency to higher frequency for the digits having the same degree of significance.

19. The scalable audio coding method according to claim 17, wherein the coding steps (b), (c) and (d) are performed on side information having at least quantization step size information and quantization bit information allotted to each band, by a predetermined coding method.

20. The scalable audio coding method according to claim 18, wherein the digits in the steps (e) and (f) are bits.

21. The scalable audio coding method according to claim 19, wherein the digits in the steps (e) and (f) are bits.

22. The scalable audio coding method according to claim 21, wherein the coding in the step (f) is performed by coupling bits composing the bit sequences into units of bits of a predetermined number.

23. The scalable audio coding method according to claim 21, wherein the predetermined coding method is lossless coding.

24. The scalable audio coding method according to claim 22, wherein the predetermined coding method is lossless coding.

25. The scalable audio coding method according to claim 23, wherein the lossless coding is Huffman coding.

26. The scalable audio coding method according to claim 24, wherein the lossless coding is Huffman coding.

27. The scalable audio coding method according to claim 23, wherein the lossless coding is Arithmetic coding.

28. The scalable audio coding method according to claim 24, wherein the lossless coding is Arithmetic coding.

29. The scalable audio coding method according to claim 16, wherein, when the quantized data is composed of sign data and magnitude data, the step (f) comprises the steps of:

i) coding the most significant digit sequences composed of most significant digits of the magnitude data composing the represented digital data by a predetermined coding method;

ii) coding sign data corresponding to non-zero data among the coded most significant digit sequences;

iii) coding the most significant digit sequences among the not coded magnitude data of the digital data by a predetermined coding method;

iv) coding the not coded sign data among the sign data corresponding to non-zero magnitude data among digit sequences coded in the stop (iii); and

v) performing the steps (iii) and (iv) on the respective digits of the digital date.

30. The scalable audio coding method according to claim 29, wherein the step (e) is to represent the digital data as binary data having bits of the same number, and the digits are bits.

31. The scalable audio coding method according to claim 29, wherein the coding steps are performed by coupling bits composing the respective bit sequences for the magnitude data and sign data, into units of bits of a predetermined number.

32. The scalable audio coding method according to claim 30, wherein the predetermined coding method is Arithmetic coding.

33. The scalable audio coding method according to claim 31, wherein the predetermined coding method is Arithmetic coding.

34. The scalable audio decoding method according to claim 33, said second range of frequencies includes frequencies different from said first range of frequencies wherein the most significant digits of the quantized data of said frequencies different from said first range of frequencies are decoded before decoding next significant digits of the quantized data belonging to the corresponding enhancement layer.

35. The scalable audio coding method according to claim 29, wherein the coding steps (b), (c) and (d) are performed on side information having at least quantization step size information and quantization bit information allotted to each band, by a predetermined coding method.

36. The scalable audio coding method according to claim 16, wherein quantization is performed by the steps of:

converting the input audio signals of a temporal domain into signals of a frequency domain;

coupling the converted signals as signals of predetermined subbands by time/frequency mapping and calculating a masking threshold at each subband; and

quantizing the signals for each predetermined coding band so that quantization noise of each band is smaller than the masking threshold.

37. The scalable audio coding method according to claim 29, wherein quantization is performed by the steps of:

converting the input audio signals of a temporal domain into signals of a frequency domain;

coupling the converted signals as signals of predetermined subbands by time/frequency mapping and calculating a masking threshold at each subband; and

quantizing the signals for each predetermined coding band so that quantization noise of each band is smaller than the masking threshold.

38. A scalable audio decoding method for decoding the coded layered datastream having a base layer and enhancement layers of a predetermined number into audio signals, comprising the steps of:

(a) decoding the coded bass layer of a first range of frequencies, having a predetermined layer size, into the quantized data;

(b) decoding the coded next enhancement layer of a second range of frequencies, having a predetermined layer size, into the quantized data; and

(c) sequentially performing the layer decoding steps for all layers;

(d) dequantizing said quantized data into said audio signals, wherein the steps (a), (b) and (c) each comprise the steps of;

(e) determining the number of the quantization digits of each quantizing band; and

(f) decoding the coded data as the most significant digit sequences, which represents the magnitude of said quantized data, when the number of the quantizing digits of the respective quantization band is equal to a predetermined same number.