Method and apparatus for encoding and decoding audio information

• US 5,479,562 A
• Filed: 06/18/1993
• Issued: 12/26/1995
• Est. Priority Date: 01/27/1989
• Status: Expired due to Term

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Davidson, Grant A., Fielder, Louis D.
• Primary Examiner(s): Knepper, David D.
• Application Number:
  US08/079,169
• Time in Patent Office: 921 Days
• Field of Search: 395/2, 395/2.1, 395/2.12, 395/2.15, 395/2.33, 395/2.34, 395/2.38, 395/2.39, 381/29-40
• US Class Current: 704/229
• CPC Class Codes: G06T 9/005 Statistical coding, e.g. Huffman, run length coding
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/16 Vocoder architecture
• CPC Class Codes: H04B 1/665 using psychoacoustic properties of the ear, e.g. masking effect

Abstract

The invention relates to formatting encoded audio information in a form suitable for transmission or storage. Audio information is encoded into a binary form, using an invariant number of bits to represent at least some but not all of the encoded information. The information represented by an invariant number of bits is assembled into pre-established positions within a formatted frame.

Claims

1. An encoder for the encoding of audio information comprising signal samples, said encoder comprising

means for receiving said signal samples,

subband means, including adaptive bit allocation means, for generating subband information comprising digital words in response to said signal samples, wherein said adaptive bit allocation means allocates an adaptive number of bits to represent at least a portion of at least some of said digital words, and wherein at least a portion of some of said digital words is represented by an invariant number of bits, and

formatting means for assembling digital information including said digital words into a digital output having a format suitable for transmission or storage, wherein said formatting means places said portion of digital words represented by an invariant number of bits into one or more pre-established positions within a frame of said digital output.

2. An encoder according to claim 1 wherein said formatting means assembles said digital information such that said portion of digital words placed into said one or more pre-established positions is placed ahead of other portions of said digital words within said frame.

3. An encoder according to claim 1 wherein said formatting means places said portion of digital words represented by an invariant number of bits into adjacent positions within said frame.

9. An encoder according to any one of claims 1, 2, 7 or 8 wherein said digital words comprise scaling factors and scaled values, and wherein said portion of digital words to which an adaptive number of bits is allocated constitutes at least a portion of at least some of said scaled values.

4. A decoder of a formatted signal comprising digital words, said decoder comprising

deformatting means for obtaining said digital words from said formatted signal, wherein at least a portion of some of said digital words are represented by an invariant number of bits and at least a portion of at least some of said digital words are represented by an adaptive number of bits, said portion of digital words represented by an invariant number of bits is obtained from one or more pre-established positions within a frame of said formatted signal, and said portion of digital words represented by an adaptive number of bits is obtained from one or more positions within said frame established in response to said portion of subband signals represented by an invariant number of bits,

inverse subband means for generating signal samples in response to said digital words, and

means for sending said signal samples.

5. A decoder according to claim 4 wherein said deformatting means obtains said portion of digital words from said one or more pre-established positions which are ahead of other portions of said digital words within said frame.

6. A decoder according to claim 4 wherein said deformatting means obtains said portion of digital words represented by an invariant number of bits from adjacent positions within said frame.

7. An encoder for the encoding of audio information comprising signal samples, said encoder comprising

means for receiving said signal samples,

subband means, including adaptive bit allocation means, for generating subband information comprising digital words in response to said signal samples, wherein said adaptive bit allocation means allocates an adaptive number of bits to represent at least a portion of at least some of said digital words, and wherein at least a portion of some of said digital words is represented by an invariant number of bits, and

formatting means for assembling digital information including said digital words into a digital output having a format suitable for transmission or storage, wherein said formatting means places said portion of digital words represented by an invariant number of bits into adjacent positions within a frame of said digital output.

8. An encoder according to claim 7 wherein said formatting means assembles said digital information such that said portion of digital words placed into said adjacent positions is placed ahead of other portions of said digital words within said frame.

10. A decoder of a formatted signal comprising digital words, said decoder comprising

deformatting means for obtaining said digital words from said formatted signal, wherein at least a portion of some of said digital words are represented by an invariant number of bits and at least a portion of at least some of said digital words are represented by an adaptive number of bits, said portion of digital words represented by an invariant number of bits is obtained from one or more adjacent positions within a frame of said formatted signal, and said portion of digital words represented by an adaptive number of bits is obtained from one or more positions within said frame established in response to said portion of subband signals represented by an invariant number of bits,

inverse subband means for generating signal samples in response to said digital words, and

means for sending said signal samples.

11. A decoder according to claim 10 wherein said deformatting means obtains said portion of digital words from said one or more adjacent positions which are ahead of other portions of said digital words within said frame.

12. A decoder according to any one of claims 4, 5, 10 or 11 wherein said digital words comprise scaling factors and scaled values, and wherein said portion of digital words represented by an adaptive number of bits constitutes at least a portion of at least some of said scaled values.

13. An encoder for the encoding of audio information comprising signal samples, said encoder comprising

means for receiving said signal samples,

subband means for generating, in response to said signal samples, subband signals comprising scaling factors and associated scaled values, and

formatting means for assembling digital information including said subband signals into a digital output having a format suitable for transmission or storage, wherein said formatting means places said scaling factors into adjacent positions within a frame of said digital output.

14. An encoder according to claim 13 wherein said subband means generates subband signals comprising one or more blocks of scaled values, each block comprising one or more scaled values associated with a respective scaling factor.

15. An encoder according to claim 14 wherein said subband means generates subband signals comprising two or more sets of respective blocks of scaled values, wherein a respective block of scaled values in each set is associated with a respective common scaling factor.

16. An encoder according to claim 13 wherein said subband means generates subband signals comprising two or more sets of respective scaled values, wherein a respective scaled value in each set is associated with a respective common scaling factor.

21. An encoder according to any one of claims 13 through 20 wherein said subband means generates subband signals represented in a floating-point form, wherein said scaling factors are exponents and said scaled values are mantissas.

22. An encoder according to any one of claims 13 through 20 wherein said formatting means assembles said digital information such that scaling factors placed into said adjacent positions are placed ahead of said scaled values within said frame.

17. An encoder for the encoding of audio information comprising signal samples, said encoder comprising

means for receiving said signal samples,

subband means for generating, in response to said signal samples, subband signals comprising scaling factors and associated scaled values, and

formatting means for assembling digital information including said subband signals into a digital output having a format suitable for transmission or storage, wherein said formatting means places said scaling factors into one or more pre-established positions within a frame of said digital output.

18. An encoder according to claim 17 wherein said subband means generates subband signals comprising one or more blocks of scaled values, each block comprising one or more scaled values associated with a respective scaling factor.

19. An encoder according to claim 18 wherein said subband means generates subband signals comprising two or more sets of respective blocks of scaled values, wherein a respective block of scaled values in each set is associated with a respective common scaling factor.

20. An encoder according to claim 17 wherein said subband means generates subband signals comprising two or more sets of respective scaled values, wherein a respective scaled value in each set is associated with a respective common scaling factor.

23. A decoder of a formatted signal including subband signals comprising scaling factors and scaled values, said decoder comprising

deformatting means for deriving said subband signals by obtaining said scaling factors from adjacent positions within a frame of said formatted signal and by obtaining said scaled values from said formatted signal,

inverse subband means for generating signal samples in response to said derived subband signals, and

means for sending said signal samples.

24. A decoder according to claim 23 wherein said deformatting means obtains subband signals comprising one or more blocks of scaled values, each block comprising one or more scaled values associated with a respective scaling factor.

25. A decoder according to claim 24 wherein said deformatting means obtains subband signals comprising two or more sets of respective blocks of scaled values, wherein a respective block of scaled values in each set is associated with a respective common scaling factor.

26. A decoder according to claim 23 wherein said deformatting means obtains subband signals comprising two or more sets of respective scaled values, wherein a respective scaled value in each set is associated with a respective common scaling factor.

31. A decoder according to any one of claims 23 through 30 wherein said deformatting means obtains subband signals represented in a floating-point form, wherein said scaling factors are exponents and said scaled values are mantissas.

32. A decoder according to any one of claims 23 through 30 wherein said deformatting means obtains said scaling factors from said adjacent positions ahead of said scaled values within said frame.

27. A decoder of a formatted signal including subband signals comprising scaling factors and scaled values, said decoder comprising

deformatting means for deriving said subband signals by obtaining said scaling factors from one or more pre-established positions within a frame of said formatted signal and by obtaining said scaled values from said formatted signal,

inverse subband means for generating signal samples in response to said derived subband signals, and

means for sending said signal samples.

28. A decoder according to claim 27 wherein said deformatting means obtains subband signals comprising one or more blocks of scaled values, each block comprising one or more scaled values associated with a respective scaling factor.

29. A decoder according to claim 28 wherein said deformatting means obtains subband signals comprising two or more sets of respective blocks of scaled values, wherein a respective block of scaled values in each set is associated with a respective common scaling factor.

30. A decoder according to claim 27 wherein said deformatting means obtains subband signals comprising two or more sets of respective scaled values, wherein a respective scaled value in each set is associated with a respective common scaling factor.

33. An encoding method for the encoding of audio information comprising signal samples, said encoding method comprising

receiving said signal samples,

generating subband information comprising digital words in response to said signal samples, and allocating an adaptive number of bits to represent at least a portion of at least some of said digital words, and wherein at least a portion of some of said digital words is represented by an invariant number of bits, and

assembling digital information including said digital words into a digital output having a format suitable for transmission or storage, and placing said portion of digital words represented by an invariant number of bits into one or more pre-established positions within a frame of said digital output.

34. An encoding method according to claim 33 wherein said assembling places said portion of digital words represented by an invariant number of bits into adjacent positions within said frame.

38. An encoding method according to claim 33 or 37 wherein said generating generates digital words comprising scaling factors and scaled values, and wherein said portion of digital words to which an adaptive number of bits is allocated constitutes at least a portion of at least some of said scaled values.

35. A decoding method of a formatted signal comprising digital words, said decoding method comprising

obtaining said digital words from said formatted signal, wherein at least a portion of some of said digital words are represented by an invariant number of bits and at least a portion of at least some of said digital words are represented by an adaptive number of bits, said portion of digital words represented by an invariant number of bits is obtained from one or more pre-established positions within a frame of said formatted signal, and said portion of digital words represented by an adaptive number of bits is obtained from one or more positions within said frame established in response to said portion of subband signals represented by an invariant number of bits,

generating signal samples in response to said digital words, and

sending said signal samples.

36. A decoding method according to claim 35 wherein said portion of digital words represented by an invariant number of bits is obtained from adjacent positions within said frame.

40. A decoding method according to claim 35 or 39 wherein said digital words comprise scaling factors and scaled values, and wherein said portion of digital words represented by an adaptive number of bits constitutes at least a portion of at least some of said scaled values.

37. An encoding method for the encoding of audio information comprising signal samples, said encoding method comprising

receiving said signal samples,

generating subband information comprising digital words in response to said signal samples, and allocating an adaptive number of bits to represent at least a portion of at least some of said digital words, and wherein at least a portion of some of said digital words is represented by an invariant number of bits, and

assembling digital information including said digital words into a digital output having a format suitable for transmission or storage, and placing said portion of digital words represented by an invariant number of bits into adjacent positions within a frame of said digital output.

39. A decoding method of a formatted signal comprising digital words, said decoding method comprising

obtaining said digital words from said formatted signal, wherein at least a portion of some of said digital words are represented by an invariant number of bits and at least a portion of at least some of said digital words are represented by an adaptive number of bits, said portion of digital words represented by an invariant number of bits is obtained from one or more adjacent positions within a frame of said formatted signal, and said portion of digital words represented by an adaptive number of bits is obtained from one or more positions within said frame established in response to said portion of subband signals represented by an invariant number of bits,

generating signal samples in response to said digital words, and

sending said signal samples.

41. An encoding method for the encoding of audio information comprising signal samples, said encoding method comprising

receiving said signal samples,

generating, in response to said signal samples, subband signals comprising scaling factors and associated scaled values, and

assembling digital information including said subband signals into a digital output having a format suitable for transmission or storage, and placing said scaling factors into adjacent positions within a frame of said digital output.

43. An encoding method according to claim 41 or 42 wherein said generating generates subband signals comprising one or more blocks of scaled values, each block comprising one or more scaled values associated with a respective scaling factor.

44. An encoding method according to claim 41 or 42 wherein said generating generates subband signals comprising two or more sets of respective scaled values, wherein a respective scaled value in each set is associated with a respective common scaling factor.

42. An encoding method for the encoding of audio information comprising signal samples, said encoding method comprising

receiving said signal samples,

generating, in response to said signal samples, subband signals comprising scaling factors and associated scaled values, and

assembling digital information including said subband signals into a digital output having a format suitable for transmission or storage, and placing said scaling factors into one or more pre-established positions within a frame of said digital output.

45. A decoding method of a formatted signal including subband signals comprising scaling factors and scaled values, said decoding method comprising

deriving said subband signals by obtaining said scaling factors from adjacent positions within a frame of said formatted signal and by obtaining said scaled values from said formatted signal,

generating signal samples in response to said derived subband signals, and

sending said signal samples.

47. A decoding method according to claim 45 or 46 wherein said subband signals comprise one or more blocks of scaled values, each block comprising one or more scaled values associated with a respective scaling factor.

48. A decoding method according to claim 45 or 46 wherein said subband signals comprise two or more sets of respective scaled values, wherein a respective scaled value in each set is associated with a respective common scaling factor.

46. A decoding method of a formatted signal including subband signals comprising scaling factors and scaled values, said decoding method comprising

deriving said subband signals by obtaining said scaling factors from one or more pre-established positions within a frame of said formatted signal and by obtaining said scaled values from said formatted signal,

generating signal samples in response to said derived subband signals, and

sending said signal samples.