Scalable audio coding/decoding method and apparatus without overlap of information between various layers

• US 6,108,625 A
• Filed: 04/02/1998
• Issued: 08/22/2000
• Est. Priority Date: 04/02/1997
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Yeon-bae
• Primary Examiner(s): Voeltz, Emanuel Todd
• Assistant Examiner(s): SOFOCLEOUS, MICHAEL D
• Application Number:
  US09/053,664
• Time in Patent Office: 873 Days
• Field of Search: 704/229, 704/230, 704/205
• US Class Current: 704/229
• 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 comprise the steps of: (i) obtaining gamut bit allocation information representing the number of bits of the quantized data corresponding to the respective subbands belonging to a layer to be coded; (ii) obtaining the number of bits allocated to the respective subbands within each subband size of the layers; (iii) generating an index representing the presence of quantized data for predetermined frequency components forming the subbands for the quantized data corresponding to the number of allocated bits; and (iv) generating bitstreams by coding the quantized data corresponding to the gamut bit allocation information, quantization step size, index and number of bits allocated to the respective subbands, by a predetermined coding method.

Claims

1. A computer usable medium having computer readable program code means embodied therein for coding audio signals into a layered datastream having a base layer and a predetermined number of enhancement layers, the computer readable program code means in said computer usable medium comprising:

(a) computer readable program code means for causing a computer to effect signal-processing of input audio signals and quantizing the same for each predetermined coding band;

(b) computer readable program code means for causing a computer to effect coding of the quantized data corresponding to the base layer within a predetermined layer size;

(c) computer readable program code means for causing a computer to effect coding of 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) computer readable program code means for causing a computer to effect sequentially performance of the layer coding steps for all layers, wherein the computer readable program code means (b), (c) and (d) each comprise;

(i) computer readable program code means for causing a computer to effect obtaining gamut bit allocation information representing the number of bits of the quantized data corresponding to the respective subbands belonging to a layer to be coded;

(ii) computer readable program code means for causing a computer to effect obtaining the number of bits allocated to the respective subbands within each subband size of the layers;

(iii) computer readable program code means for causing a computer to effect generating an index representing the presence of quantized data for predetermined frequency components forming the subbands for the quantized data corresponding to the number of allocated bits; and

(iv) computer readable program code means for causing a computer to effect generating bitstreams by coding the quantized data corresponding to the gamut bit allocation information, quantization step size, index and number of bits allocated to the respective subbands, by a predetermined coding method.

2. The computer usable medium according to claim 1, wherein the quantized data corresponding to the number of allocated bits is quantized from the most significant bit to the least significant bit.

3. The computer usable medium according to claim 2, wherein coding of the quantized data corresponding to the number of allocated bits is performed in the computer readable program code means (iv) by coupling the quantized data in units of bits of a predetermined number.

4. The computer usable medium according to claim 2, wherein the number of allocated bits in the computer readable program code means (ii) is one bits, and the computer readable program code means (iv) is to generate the gamut bit allocation information and index as bitstreams by a predetermined coding method.

5. The computer usable medium according to claim 1, wherein the predetermined coding method is lossless coding.

6. The computer usable medium according to claim 5, wherein the lossless coding is Huffman coding.

7. The computer usable medium according to claim 5, wherein the lossless coding is Arithmetic coding.

8. The computer usable medium according to claim 1, wherein the computer readable program code means(a) comprises:

computer readable program code means for causing a computer to effect converting the input audio signals of a temporal domain into signals of a frequency domain;

computer readable program code means for causing a computer to effect coupling the converted signals as signals of predetermined subbands by time/frequency mapping and calculating a masking threshold at each subband; and

computer readable program code means for causing a computer to effect quantizing the signals for each predetermined coding band so that quantization noise of each band is smaller than the masking threshold.

9. A computer usable medium having computer readable program code means embodied therein for decoding audio data coded to have layered bitrates, the computer readable program code means in said computer usable medium comprising:

computer readable program code means for causing a computer to effect decoding gamut bit allocation information for each subband of a base layer, representing the number of bits of quantized data of the respective subbands belonging to the base layer, index representing the presence of data for predetermined frequency components of the quantized data corresponding to the number of bits allocated to the respective subbands, quantization step size and the quantized data, in the generated order of the layers of the bitstreams, decoding being performed by obtaining the number of bits allocated to the subbands belonging to each layer and decoding the quantized data corresponding to the number of allocated bits referring to the index;

computer readable program code means for causing a computer to effect restoring the decoded quantization step size and quantized data into signals having the original magnitudes; and

computer readable program code means for causing a computer to effect converting dequantized signals of a frequency domain into signals of a temporal domain.

10. The computer usable medium according to claim 9, wherein decoding the quantized data in the decoding process is performed from the most significant bit to lower significant bits.

11. The computer usable medium according to claim 9, wherein decoding the quantized data in the decoding process is performed in units of vectors of bits of a predetermined number.

12. The computer usable medium according to claim 9, wherein the decoding step is performed by Arithmetic decoding.

13. The computer usable medium according to claim 9, wherein the decoding step is performed by Huffman decoding.

14. A computer usable medium having embodied thereon a computer program for coding audio signals into a layered datastream having a base layer and a predetermined number of enhancement layers, the computer program being executable by a machine to perform:

(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 comprise the steps of;

(i) obtaining gamut bit allocation information representing the number of bits of the quantized data corresponding to the respective subbands belonging to a layer to be coded;

(ii) obtaining the number of bits allocated to the respective subbands within each subband size of the layers;

(iii) generating an index representing the presence of quantized data for predetermined frequency components forming the subbands for the quantized data corresponding to the number of allocated bits; and

(iv) generating bitstreams by coding the quantized data corresponding to the gamut bit allocation information, quantization step size, index and number of bits allocated to the respective subbands, by a predetermined coding method.

15. The computer usable medium according to claim 14, wherein the quantized data corresponding to the number of allocated bits is quantized from the most significant bit to the least significant bit.

16. The computer usable medium according to claim 15, wherein coding of the quantized data corresponding to the number of allocated bits is performed in (iv) by coupling the quantized data in units of bits of a predetermined number.

17. The computer usable medium according to claim 15, wherein the number of allocated bits in (ii) is one bit, and (iv) is to generate the gamut bit allocation information and index as bitstreams by a predetermined coding method.

18. The computer usable medium according to claim 14, wherein as part of (a) the computer program being executable by a machine to perform:

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.

19. A computer usable medium having embodied thereon a computer program for decoding audio data coded to have layered bitrates, the computer program being executable by a machine to perform:

decoding gamut bit allocation information for each subband of a base layer, representing the number of bits of quantized data of the respective subbands belonging to the base layer, index representing the presence of data for predetermined frequency components of the quantized data corresponding to the number of bits allocated to the respective subbands, quantization step size and the quantized data, in the generated order of the layers of the bitstreams, decoding being performed by obtaining the number of bits allocated to the subbands belonging to each layer and decoding the quantized data corresponding to the number of allocated bits referring to the index;

restoring the decoded quantization step size and quantized data into signals having the original magnitudes; and

converting dequantized signals of a frequency domain into signals of a temporal domain.

20. The computer readable medium according to claim 19, wherein decoding the quantized data in the decoding step is performed from the most significant bit to lower significant bits.

21. The computer readable medium according to claim 19, wherein decoding the quantized data in the decoding step is performed in units of vectors of bits of a predetermined number.

22. A computer usable medium having embodied thereon a computer program for coding audio signals into a layered datastream having a base layer and a predetermined number of enhancement layers, the computer program executable by a machine to perform:

(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;

(i) obtaining gamut bit allocation information representing the number of bits of the quantized data corresponding to the respective subbands belonging to a layer to be coded;

(ii) obtaining the number of bits allocated to the respective subbands within each subband size of the layers;

(iii) generating an index representing the presence of quantized data for predetermined frequency components forming the subbands for the quantized data corresponding to the number of allocated bits; and

(iv) generating bitstreams by coding the quantized data corresponding to the gamut bit allocation information, quantization step size, index and number of bits allocated to the respective subbands, by a predetermined coding method.

23. The computer usable medium according to claim 22, wherein 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.

24. The computer usable medium according to claim 23, wherein the quantized data corresponding to the number of allocated bits is quantized from the most significant bit to the least significant bit.

25. The computer usable medium according to claim 24, wherein coding of the quantized data corresponding to the number of allocated bits is performed in the step (iv) by coupling the quantized data in units of bits of a predetermined number.

26. The computer usable medium according to claim 24, wherein the number of allocated bits in the step (ii) is one bits, and the step (iv) is to generate the gamut bit allocation information and index as bitstreams by a predetermined coding method.

27. The computer usable medium according to claim 23, wherein the predetermined coding method is lossless coding.

28. The computer usable medium according to claim 27, wherein the lossless coding is Huffman coding.

29. The computer usable medium according to claim 27, wherein the lossless coding is Arithmetic coding.

30. The computer usable medium according to claim 23, wherein the step (a) additionally comprises 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.