Scalable audio coding/decoding method and apparatus

• US 6,438,525 B1
• Filed: 07/07/2000
• Issued: 08/20/2002
• 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): {haeck over (S)}mits, Ta̅livaldis Ivars
• Assistant Examiner(s): Azad, Abul K.
• Application Number:
  US09/612,630
• Time in Patent Office: 774 Days
• Field of Search: 704/500, 704/501, 704/503, 704/229, 704/230, 704/222
• 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 apparatus for coding audio signals to have layered bitrate data of a predetermined number, comprising:

a quantizing portion for signal-processing input audio signals and directly quantizing the same for each coding band; and

a bit packing portion for generating bitstreams by coding side information corresponding to a base layer and sliced digits of the quantized data, and coding side information corresponding to the next layer of the base layer and uncoded sliced digits of the quantized data, to perform coding on all layers,

wherein the bit packing portion performs the coding by representing the quantized data by binary data having bits of a predetermined number to slice the same into units of bits, and coding the bit-sliced data from the most significant bit sequence to the least significant bit sequence, by a predetermined coding method.

2. The scalable audio coding apparatus according to claim 1, wherein, when side information data is composed of sign data and magnitude data, the bit packing portion collects and codes the magnitude data for the bits having the same significance level among the bit-sliced data, codes uncoded sign data among the sign data corresponding to non-zero magnitude data, the magnitude and sign data coding is performed sequentially from the MSBs to lower significant bits.

3. The scalable audio coding apparatus according to claim 2, wherein, when the bit packing portion collects and codes the bits according to significance, coding is performed by coupling the bits in a predetermined number unit.

4. The scalable audio coding apparatus according to claim 2, wherein the bit packing portion performs coding by either Huffinan coding or Arithmetic coding.

5. The scalable audio coding apparatus according to claim 2, wherein the bit packing portion performs coding sequentially from low frequency components to high frequency components.

6. The scalable audio coding apparatus according to claim 2, wherein the quantizing portion comprises:

a time/frequency mapping portion for converting the input audio signals of a temporal domain into signals of a frequency domain.

7. The scalable audio coding apparatus according to claim 2, wherein the quantizing portion comprises:

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

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

8. The scalable audio coding apparatus according to claim 1, wherein, when the bit packing portion codes the bits according to significance, coding is performed by coupling the bits in a predetermined number unit.

9. The scalable audio coding apparatus according to claim 1, wherein the bit packing portion performs coding by either Huffman coding or Arithmetic coding.

10. The scalable audio coding apparatus according to claim 1, wherein the bit packing portion performs coding sequentially from low frequency components to high frequency components.

11. The scalable audio coding apparatus according to claim 1, wherein the quantizing portion comprises:

a time/frequency mapping portion for converting the input audio signals of a temporal domain into signals of a frequency domain.

12. The scalable audio coding apparatus according to claim 11, wherein the quantizing portion comprises:

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

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

13. A scalable audio decoding method for decoding audio data coded to have layered bitrates, comprising the steps of:

decoding side information having at least quantization step size information and quantization bit information allotted to each band, in the order of creation of the layers in datastreams having layered bitrates, by analyzing the significance of bits composing the datastreams, from upper significant bits to lower significant bits;

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

converting inversely quantized signals into signals of a temporal domain.

14. The scalable audio decoding method according to claim 13, wherein the digits in the decoding step are bits, and the datastreams are bitstreams.

15. The scalable audio decoding method according to claim 14, wherein, when the quantized data is composed of sign data and magnitude data, the decoding step is performed by:

decoding side information having at least quantization step size information and quantization bit information allotted to each band, and the quantized data, in the order of creation of layers in datastreams having layered bitrates, by analyzing the significance of bits composing the datastreams, from upper significant bits to lower significant bits; and

decoding the sign data of the quantized data and combining the same with the decoded magnitude data.

16. The scalable audio decoding method according to claim 14, wherein the decoding step is performed by Arithmetic decoding.

17. The scalable audio decoding method according to claim 14, wherein the decoding step is performed by Huffman decoding.

18. The scalable audio decoding method according to claim 14, wherein the decoding step according to significance is performed in units of vectors comprised of bits of a predetermined number.

19. The scalable audio decoding method according to claim 18, wherein, when the quantized data is composed of sign data and magnitude data, the decoding step is performed by:

decoding side information having at least quantization step size information and quantization bit information allotted to each band, and the quantized data, in the order of creation of layers in datastreams having layered bitrates, by analyzing the significance of bits composing the datastreams, from upper significant bits to lower significant bits; and

decoding the sign data of the quantized data and combining the same with the decoded magnitude data.

20. A scalable audio decoding apparatus for decoding audio data coded to have layered bitrates, comprising:

a bitstream analyzing portion for decoding side information having at least quantization step size information and quantization bit information allotted to each band, and the quantized data, in the order of creation of the layers in layered bitstreams, by analyzing the significance of bits composing the bitstreams, from upper significant bits to lower significant bits;

an inverse quantizing portion for restoring the decoded quantization step size and quantized data into signals having the original magnitudes; and

a frequency/time mapping portion for converting inversely quantized signals into signals of a temporal domain.