Apparatus and method for audio data compression and expansion with reduced block floating overhead

• US RE36,683 E
• Filed: 12/18/1996
• Issued: 05/02/2000
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Tsutsui, Kyoya
• Primary Examiner(s): Hudspeth, David R.
• Assistant Examiner(s): ZINTEL, HAROLD ALBERT
• Application Number:
  US08/767,840
• Time in Patent Office: 1,231 Days
• Field of Search: 395/2.38, 395/2.12, 395/2.13, 395/2.91, 704/229, 704/223, 704/204, 704/500, 704/230, 704/205
• US Class Current: 704/229
• CPC Class Codes: H04B 1/665 using psychoacoustic properties of the ear, e.g. masking effect
• CPC Class Codes: H04B 1/667 using a division in frequency subbands for TV signals H04N19/63

Abstract

A method for compressing a digital audio input signal to provide a recording signal in which the input signal is divided into frames comprising plural samples. Each frame is transformed into a block of spectral coefficients, which are divided into plural bands. For each band, block floating is applied to the spectral coefficients therein; a block floating coefficient is generated; the spectral coefficients are quantized with an adaptive number of bits to provide quantized spectral coefficients; and a word length is generated. Finally, there is added to the recording signal a block of data derived from the block of spectral coefficients and consisting of the quantized spectral coefficients, a main word length and a main block floating coefficient for each band, and a reserve word length at least for each lower frequency band. In a variation, zero bits are allocated to quantize the spectral coefficients in bands higher in frequency than a highest usable band. The block of data consists of the quantized spectral coefficients, at least one word length, and at least one block floating coefficient, for each band up to the highest usable band; and data indicating the number of bands up to the highest usable band.

Claims

1. A method for compressing a digital audio input signal to provide a recording signal, the method comprising the steps of:

dividing the input signal into frames comprising plural samples;

transforming each frame of plural samples into a block of spectral coefficients and dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands, and a lowest frequency band;

applying block floating to the spectral coefficients in each band and generating a block floating coefficient for each band;

quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and generating a word length for each band;

adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band, and

a reserve word length at least for each of the lower frequency bands.

2. The method for compressing a digital audio input signal of claim 1, wherein, the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length at least for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients.

3. [.The method for compressing a digital audio input signal of claim 1, wherein, in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients additionally consists of.]. .Iadd.A method for compressing a digital audio input signal to provide a recording signal, the method comprising the steps of:

dividing the input signal into frames comprising plural samples;

transforming each frame of plural samples into a block of spectral coefficients and dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands, and a lowest frequency band;

applying block floating to the spectral coefficients in each band and generating a block floating coefficient for each band;

quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and generating a word length for each band;

adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band, and a reserve word length at least for each of the lower frequency bands, and .Iaddend.

a reserve block floating coefficient for each of the lower frequency bands.

4. The method for compressing a digital audio input signal of claim 3, wherein

the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the lower frequency bands.

5. The method for compressing a digital audio input signal of claim 1, wherein the step of adding a block of data derived from the block of spectral coefficients to the recording signal includes the step of arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.

6. The method for compressing a digital audio input signal of claim 5, wherein, the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients.

7. [.The method for compressing a digital audio input signal of claim 5, wherein, in the step of adding a block of data derived from the spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consists of:

.]. .Iadd.A method for compressing a digital audio input signal to provide a recording signal, the method comprising the steps of;

dividing the input signal into frames comprising plural samples;

transforming each frame of plural samples into a block of spectral coefficients and dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands, and a lowest frequency band;

applying block floating to the spectral coefficients in each band and generating a block floating coefficient for each band;

quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and generating a word length for each band;

adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

.Iaddend.

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band,

a reserve word length for each of a first number of the lower frequency bands, and

a reserve block floating coefficient for each of a second number of lower frequency bands, the second number of lower frequency bands being less than the first number of lower frequency bands.Iadd., and wherein the step of adding a block of data derived from the block of spectral coefficients to the recording signal includes the step of arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.Iaddend..

8. The method for compressing a digital audio input signal of claim 7, wherein,

the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the first number of lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the second number of lower frequency bands.

9. [.The method for compressing a digital audio input signal of claim 1, wherein, in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consists of:

.]. .Iadd.A method for compressing a digital audio input signal to provide a recording signal, the method comprising the steps of;

dividing the input signal into frames comprising plural samples;

transforming each frame of plural samples into a block of spectral coefficients and dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands, and a lowest frequency band;

applying block floating to the spectral coefficients in each band and generating a block floating coefficient for each band;

quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and generating a word length for each band;

adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

.Iaddend.

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band,

a reserve word length for each band, and

a reserve block floating coefficient for each of the lower frequency bands.

10. The method for compressing a digital audio input signal of claim 9, wherein

the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the lower frequency bands.

11. A method for compressing a digital audio input signal to provide a recording signal, the method comprising the steps of:

dividing the input signal into frames comprising plural samples;

transforming each frame of plural samples into a block of spectral coefficients and dividing the block of spectral coefficients into plural bands, the plural bands including a lowest frequency band, and a highest frequency band;

generating block floating parameters;

applying block floating to the spectral coefficients in each band in response to a block floating parameter;

quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in response to a block floating parameter, zero bits being allocated to the spectral coefficients in bands higher in frequency than a highest usable band;

adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

the quantized spectral coefficients for each band up to the highest usable band, there being a number of bands up to the highest useable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest usable band.

12. The method for compressing a digital audio input signal of claim 11, wherein, the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a difference between a number of bits required to provide block floating parameters for each band and a number of bits required to provide block floating parameters for each band up to the highest useable band.

13. The method for compressing a digital audio input signal of claim 11, wherein

the block floating parameters include a word length and a block floating coefficient,

the step of applying block floating includes the step of applying block floating in response to the block floating coefficient,

the step of quantizing the spectral coefficients includes the step of quantizing the spectral coefficients in response to the word length, and

in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block floating parameters in block of data derived from the block of spectral coefficients consist of:

a main word length for each band up to the highest useable band,

a main block floating coefficient for each band up to the highest useable band, and

a reserve word length for each of the lower frequency bands.

14. [.The method for compressing a digital audio input signal of claim 13, wherein in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block floating parameters in block of data derived from the block of spectral coefficients additionally consist of.]. .Iadd.The method for compressing a digital audio input signal of claim 11, wherein

the block floating parameters include a word length and a block floating coefficient,

the step of applying block floating includes the step of applying block floating in response to the block floating coefficient,

the step of quantizing the spectral coefficients includes the step of quantizing the spectral coefficients in response to the word length,

in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block floating parameters in block of data derived from the block of spectral coefficients consist of:

a main word length for each band up to the highest useable band,

a main block floating coefficient for each band up to the highest useable band,

a reserve word length for each of the lower frequency bands, and .Iaddend.

a reserve block floating coefficient for each of the lower frequency bands.

15. The method for compressing a digital audio input signal of claim 13, wherein the step of adding a block of data derived from the block of spectral coefficients to the recording signal includes the step of arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.

16. [.The method for compressing a digital audio input signal of claim 15, wherein,.]. .Iadd.The method for compressing a digital audio input signal of claim 11, wherein

the block floating parameters include a word length and a block floating coefficient,

the step of applying block floating includes the step of applying block floating in response to the block floating coefficient,

the step of quantizing the spectral coefficients includes the step of quantizing the spectral coefficients in response to the word length, and .Iaddend.in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block floating parameters in block of data derived from the block of spectral coefficients consist of:

a main word length for each band up to the highest useable band,

a main block floating coefficient for each band up to the highest useable band,

a reserve word length for each of a first number of the lower frequency bands, and

a reserve block floating coefficient for each of second number of lower frequency bands, the second number of lower frequency bands being less than the first number of lower frequency bands.Iadd., wherein the step of adding a block of data derived from the block of spectral coefficients to the recording signal includes the step of arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.Iaddend..

17. An apparatus for compressing a digital audio input signal to provide a recording signal, the apparatus comprising:

a means for dividing the input signal into frames comprising plural samples;

a means for transforming each frame of plural samples into a block of spectral coefficients and for dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands;

a means for applying block floating to the spectral coefficients in each band and for generating a block floating coefficient for each band;

a quantizing means for quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and for generating a word length for each band;

a means for adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band, and

a reserve word length at least for each of the lower frequency bands.

18. The apparatus for compressing a digital audio input signal of claim 17, wherein, the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients.

19. [.The apparatus for compressing a digital audio input signal of claim 17, wherein, the block of data derived from the block of spectral coefficients additionally consists of.]. .Iadd.An apparatus for compressing a digital audio input signal to provide a recording signal, the apparatus comprising:

a means for dividing the input signal into frames comprising plural samples;

a means for transforming each frame of plural samples into a block of spectral coefficients and for dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands;

a means for applying block floating to the spectral coefficients in each band and for generating a block floating coefficient for each band;

a quantizing means for quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and for generating a word length for each band;

a means for adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

the quantized spectral coefficients;

a main word length for each band,

a main block floating coefficient for each band,

a reserve word length at least for each of the lower frequency bands, and .Iaddend.

a reserve block floating coefficient for each of the lower frequency bands.

20. The apparatus for compressing a digital audio input signal of claim 19, wherein, the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the lower frequency bands.

21. The apparatus for compressing a digital audio input signal of claim 17, wherein the adding means includes a means for arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.

22. The apparatus for compressing a digital audio input signal of claim 21, wherein,

the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients.

23. [.The apparatus for compressing a digital audio input signal of claim 21, wherein the block of data derived from the block of spectral coefficients consists of:

.]. .Iadd.An apparatus for compressing a digital audio input signal to provide a recording signal, the apparatus comprising;

a means for dividing the input signal into frames comprising plural samples;

a means for transforming each frame of plural samples into a block of spectral coefficients and for dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands;

a means for applying block floating to the spectral coefficients in each band and for generating a block floating coefficient for each band;

a quantizing means for quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and for generating a word length for each band;

a means for adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

.Iaddend.

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band,

a reserve word length for each of a first number of the lower frequency bands, and

a reserve block floating coefficient for each of a second number of lower frequency bands, the second number of lower frequency bands being less than the first number of lower frequency bands.Iadd., and wherein the adding means includes a means for arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.Iaddend..

24. The apparatus for compressing a digital audio input signal of claim 23, wherein, the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the first number of lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the second number of lower frequency bands.

25. [.The apparatus for compressing a digital audio input signal of claim 17, wherein the block of data derived from the block of spectral coefficients consists of:

.]. .Iadd.An apparatus for compressing a digital audio input signal to provide a recording signal, the apparatus comprising;

a means for dividing the input signal into frames comprising plural samples;

a means for transforming each frame of plural samples into a block of spectral coefficients and for dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands;

a means for applying block floating to the spectral coefficients in each band and for generating a block floating coefficient for each band;

a quantizing means for quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and for generating a word length for each band;

a means for adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

.Iaddend.

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band,

a reserve word length for each band, and

a reserve block floating coefficient for each of the lower frequency bands.

26. The apparatus for compressing a digital audio input signal of claim 25, wherein the quantizing means quantizes the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the lower frequency bands.

27. An apparatus for compressing a digital audio input signal to provide a recording signal, the apparatus comprising:

a means for dividing the input signal into frames comprising plural samples;

a means for transforming each frame of plural samples into a block of spectral coefficients and for dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands, and a lowest frequency band;

a means for generating block floating parameters;

a block floating means for applying block floating to the spectral coefficients in each band in response to a block floating parameter;

a quantizing means for quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in response to a block floating parameter, the quantizing means allocating zero bits to the spectral coefficients in bands higher in frequency than a highest usable band;

a means for adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients consisting of;

the quantized spectral coefficients for each band up to the highest usable band, there being a number of bands up to the highest useable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest usable band.

28. The apparatus for compressing a digital audio input signal of claim 27, wherein the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent a difference between a number of bits required to provide block floating parameters for each band and a number of bits required to provide block floating parameters for each band up to the highest useable band.

29. The apparatus for compressing a digital audio input signal of claim 27, wherein

the block floating parameters include a word length and a block floating coefficient,

the block floating means applies block floating in response to the block floating coefficient,

the quantizing means quantizes the spectral coefficients in response to the word length, and

the block floating parameters in block of data derived from the block of spectral coefficients consist of:

a main word length for each band up to the highest useable band,

a main block floating coefficient for each band up to the highest useable band, and

a reserve word length for each of the lower frequency bands.

30. [.The apparatus for compressing a digital audio input signal of claim 29, wherein the block floating parameters in block of data derived from the block of spectral coefficients additionally consist of.]. .Iadd.The apparatus for compressing a digital audio input signal of claim 27, wherein

the block floating parameters include a word length and a block floating coefficient,

the block floating means applies block floating in response to the block floating coefficient,

the quantizing means quantizes the spectral coefficients in response to the word length, and

the block floating parameters in block of data derived from the block of spectral coefficients consist of:

a main word length for each band up to the highest useable band,

a main block floating coefficient for each band up to the highest useable band,

a reserve word length for each of the lower frequency bands, and .Iaddend.

a reserve block floating coefficient for each of the lower frequency bands.

31. The apparatus for compressing a digital audio input signal of claim 29, wherein the adding means includes a means for arranging the quantized spectral coefficients sequentially in the block of data derived from the spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.

32. [.The apparatus of claim 31, wherein the block floating parameters in block of data derived from the block of spectral coefficients consist of:

.]. .Iadd.The apparatus for compressing a digital audio input signal of claim 27, wherein

the block floating parameters include a word length and a block floating coefficient,

the block floating means applies block floating in response to the block floating coefficient,

the quantizing means quantizes the spectral coefficients in response to the word length, and

the block floating parameters in block of data derived from the block of spectral coefficients consist of;

.Iaddend.

a main word length for each band up to the highest useable band,

a main block floating coefficient for each band up to the highest useable band,

a reserve word length for each of a first number of lower frequency bands.Iadd., and .Iaddend.

a reserve block floating coefficient for each of a second number of the lower frequency bands, the second number of the lower frequency bands being less than the first number of the lower frequency bands.Iadd., and

wherein the adding means includes a means for arranging the quantized spectral coefficients sequentially in the block of data derived from the spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band.Iaddend.. .Iadd.

33. An apparatus for decompressing a compressed digital signal, comprising:

an error detection circuit for generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band us to a highest usable band, there being a number of bands up to the highest usable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

a block floating coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

a word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.

34. The apparatus of claim 33, wherein the inverse orthogonal transform circuit comprises:

an inverse modified discrete cosine transformer. .Iaddend..Iadd.35. The apparatus of claim 33, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.36. The apparatus of claim 33, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal. .Iaddend..Iadd.37. The apparatus of claim 36, wherein the plurality of synthesizers comprises;

a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.38. A method for decompressing a compressed digital signal, comprising the steps of;

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

43. the time domain. .Iaddend..Iadd.69. The method of claim 68, wherein the step of transforming comprises the step of:

inverse orthogonally transforming. .Iaddend..Iadd.70. The method of claim 68, wherein the step of transforming comprises the step of;

inverse orthogonal transforming restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.71. The method of claim 70, further comprising the step of;

combining each of the inverse orthogonally transformed restored spectral

37. Iaddend..Iadd.44. The apparatus of claim 43, wherein the inverse orthogonal transform circuit comprises:

an inverse modified discrete cosine transformer. .Iaddend..Iadd.45. The apparatus of claim 43, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.46. The apparatus of claim 43, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal. .Iaddend..Iadd.47. The apparatus of claim 46, wherein the plurality of synthesizers comprises;

44. coefficients to generate an output signal. .Iaddend..Iadd.72. The method of claim 71, wherein the step of combining comprises the step of:

inverse quadrature mirror filtering. .Iaddend..Iadd.73. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method stems comprising;

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

45. the time domain. .Iaddend..Iadd.74. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method steps comprising:

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, and

block floating parameters for each band up to the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

46. the time domain. .Iaddend..Iadd.75. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method steps comprising:

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band, and data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.76. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method steps comprising;

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

47. the time domain. .Iaddend..Iadd.77. A method for compressing a digital audio input signal to provide a recording signal, the method comprising the step of:

dividing the input signal into frames comprising plural samples;

transforming each frame of plural samples into a block of spectral coefficients and dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands, and a lowest frequency band;

applying block floating to the spectral coefficients in each band and generating a block floating coefficient for each band;

quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and generating a word length for each band;

adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients comprising;

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band,

a reserve word length at least for each of the lower frequency bands, and

excluding at least one of a reserve word length for a higher frequency band, or a reserve block floating coefficient for a higher frequency band. .Iaddend..Iadd.78. The method for compressing a digital audio input signal of claim 77, wherein, the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length at least for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients. .Iaddend..Iadd.79. The method for compressing a digital audio input signal of claim 77, wherein, in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients further comprises a reserve block floating coefficient for each of the lower frequency bands. .Iaddend..Iadd.80. The method for compressing a digital audio input signal of claim 79, wherein

the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of

48. the lower frequency bands. .Iaddend..Iadd.81. The method for compressing a digital audio input signal of claim 77, wherein the step of adding a block of data derived from the block of spectral coefficients to the recording signal includes the step of arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band. .Iaddend..Iadd.82. The method for compressing a digital audio input signal of claim 81, wherein, the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients. .Iaddend..Iadd.83. The method for compressing a digital audio input signal of claim 81, wherein, in the step of adding a block of data derived from the spectral coefficients to the recording signal, the reserve word lengths comprise a reserve word length for each of a first number of the lower frequency bands, and wherein the block of data derived from the block of spectral coefficients further comprise a reserve block floating coefficient for each of a second number of lower frequency bands, the second number of lower frequency bands being less than the first number of

35. the time domain. .Iaddend..Iadd.39. The method of claim 38, wherein the step of transforming comprises the step of:

inverse orthogonally transforming. .Iaddend..Iadd.40. The method of claim 38, wherein the step of transforming comprises the step of;

inverse orthogonal transforming restored spectral coefficients in a

38. a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.48. A method for decompressing a compressed digital signal, comprising the steps of:

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, and

block floating parameters for each band up to the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.49. The method of claim 48, wherein the step of transforming comprises the step of;

39. inverse orthogonally transforming. .Iaddend..Iadd.50. The method of claim 48, wherein the step of transforming comprises the step of:

inverse orthogonal transforming restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.51. The method of claim 50, further comprising the step of;

combining each of the inverse orthogonally transformed restored spectral coefficients to generate an output signal. .Iaddend..Iadd.52. The method of claim 51, wherein the step of combining comprises the step of;

inverse quadrature mirror filtering. .Iaddend..Iadd.53. An apparatus for decompressing a compressed digital signal, comprising;

a block floating coefficient reading circuit for reading from the compressed digital signal block floating coefficients of block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

the block floating parameters being for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

a word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain.

49. lower frequency bands. .Iaddend..Iadd.84. The method for compressing a digital audio input signal of claim 83, wherein,

the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the first number of lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the second number of lower frequency bands. .Iaddend..Iadd.85. The method for compressing a digital audio input signal of claim 77, wherein, in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients further comprises:

a reserve word length for each band,

a reserve block floating coefficient for each of the lower frequency bands, and

excludes a reserve block floating coefficient for a higher frequency band. .Iaddend..Iadd.86. The method for compressing a digital audio input signal of claim 85, wherein

the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the lower frequency bands. .Iaddend..Iadd.87. A method for compressing a digital audio input signal to provide a recording signal, the method comprising the steps of;

dividing the input signal into frames comprising plural samples;

transforming each frame of plural samples into a block of spectral coefficients and dividing the block of spectral coefficients into plural bands, the plural bands including a lowest frequency bands and a highest frequency band;

generating block floating parameters;

applying block floating to the spectral coefficients in each band in response to a block floating parameter;

quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in response to a block floating parameter, zero bits being allocated to the spectral coefficients in bands higher in frequency than a highest usable band;

adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients comprising;

the quantized spectral coefficients for each band up to the highest usable band, there being a number of bands up to the highest useable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest usable band. .Iaddend..Iadd.88. The method for compressing a digital audio input signal of claim 87, wherein, the step of quantizing the spectral coefficients in each band with an adaptive number of bits includes quantizing the spectral coefficients in each band using an additional number of bits, the additional number of bits being a number of bits equivalent to a difference between a number of bits required to provide block floating parameters for each band and a number of bits required to provide block floating parameters for each band up to the highest useable band. .Iaddend..Iadd.89. The method for compressing a digital audio input signal of claim 87, wherein

the block floating parameters include a word length and a block floating coefficient,

the step of applying block floating includes the step of applying block floating in response to the block floating coefficient,

the step of quantizing the spectral coefficients includes the step of quantizing the spectral coefficients in response to the word length, and

in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block floating parameters in block of data derived from the block of spectral coefficients comprise;

a main word length for each band up to the highest useable band,

a main block floating coefficient for each band up to the highest useable band, and

a reserve word length for each of the lower frequency bands. .Iaddend..Iadd.90. The method for compressing a digital audio input signal of claim 89, wherein in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the block floating parameters in block of data derived from the block of spectral coefficients further comprise a reserve block floating coefficient for each of the lower frequency bands. .Iaddend..Iadd.91. The method for compressing a digital audio input signal of claim 89, wherein the step of adding a block of data derived from the block of spectral coefficients to the recording signal includes the step of arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band. .Iaddend..Iadd.92. The method for compressing a digital audio input signal of claim 91, wherein, in the step of adding a block of data derived from the block of spectral coefficients to the recording signal, the reserve word lengths comprise a reserve word length for each of a first number of the lower frequency bands, and wherein the block floating parameters in block of data derived from the block of spectral coefficients further comprise a reserve block floating coefficient for each of second number of lower frequency bands, the second number of lower frequency bands being less than the first number of lower frequency bands. .Iaddend..Iadd.93. An apparatus for compressing a digital audio input signal to provide a recording signal, the apparatus comprising;

means for dividing the input signal into frames comprising plural samples;

a means for transforming each frame of plural samples into a block of spectral coefficients and for dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands;

a means for applying block floating to the spectral coefficients in each band and for generating a block floating coefficient for each band;

a quantizing means for quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in each band, and for generating a word length for each band;

a means for adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients comprising;

the quantized spectral coefficients,

a main word length for each band,

a main block floating coefficient for each band, and

a reserve word length at least for each of the lower frequency bands, and

excluding at least one of a reserve word length for a high frequency bands, or a reserve block floating coefficient for a high frequency band. .Iaddend..Iadd.94. The apparatus for compressing a digital audio input signal of claim 93, wherein, the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients. .Iaddend..Iadd.95. The apparatus for compressing a digital audio input signal of claim 93, wherein, the block of data derived from the block of spectral coefficients further comprises of a reserve block floating

50. coefficient for each of the lower frequency bands. .Iaddend..Iadd.96. The apparatus for compressing a digital audio input signal of claim 95, wherein, the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the lower frequency bands. .Iaddend..Iadd.97. The apparatus for compressing a digital audio input signal of claim 93, wherein the adding means includes a means for arranging the quantized spectral coefficients sequentially in the block of data derived from the block of spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band. .Iaddend..Iadd.98. The apparatus for compressing a digital audio input signal of claim 97, wherein,

the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits required to provide a reserve word length for each band and a number of bits required to provide a reserve word length for each of the lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide no reserve block floating coefficients. .Iaddend..Iadd.99. The apparatus for compressing a digital audio input sisal of claim 97, wherein the reserve word lengths comprise a reserve word length for each of a first number of the lower frequency bands, and wherein the block of data derived from the block of spectral coefficients comprise a reserve block floating coefficient for each of a second number of lower frequency bands, the second number of lower frequency bands being less than the first number of lower frequency bands. .Iaddend..Iadd.100. The apparatus for compressing a digital audio input signal of claim 99, wherein, the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a sum of a first difference and a second difference,

the first difference being a difference between a number of bits require to provide a reserve word length for each band and a number of bits required Lo provide a reserve word length for each of the first number of lower frequency bands, and

the second difference is a difference between a number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the second number of lower frequency bands. .Iaddend..Iadd.101. The apparatus for compressing a digital audio input signal of claim 93, wherein the block of data derived from the block of spectral coefficients additionally comprises a reserve block floating coefficient for each of the lower frequency bands. .Iaddend..Iadd.102. The apparatus for compressing a digital audio input signal of claim 101, wherein the quantizing means quantizes the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent to a difference between number of bits required to provide a reserve block floating coefficient for each band and a number of bits required to provide a reserve block floating coefficient for each of the lower frequency bands. .Iaddend..Iadd.103. An apparatus for compressing a digital audio input signal to provide a recording signal, the apparatus comprising:

a means for dividing the input signal into frames comprising plural samples;

a means for transforming each frame of plural samples into a block of spectral coefficients and for dividing the block of spectral coefficients into plural bands, the plural bands including lower frequency bands, and a lowest frequency band;

a means for generating block floating parameters;

a block floating means for applying block floating to the spectral coefficients in each band in response to a block floating parameter;

a quantizing means for quantizing the spectral coefficients in each band with an adaptive number of bits to provide quantized spectral coefficients in response to a block floating parameter, the quantizing means allocating zero bits to the spectral coefficients in bands higher in frequency than a highest usable band;

a means for adding a block of data derived from the block of spectral coefficients to the recording signal, the block of data derived from the block of spectral coefficients comprising;

the quantized spectral coefficients for each band up to the highest usable band, there being a number of bands up to the highest useable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest usable band.

51. Iaddend..Iadd.104. The apparatus for compressing a digital audio input signal of claim 103, wherein the quantizing means is for quantizing the spectral coefficients in each band with an adaptive number of bits using an additional number of bits, the additional number of bits being a number of bits equivalent a difference between a number of bits required to provide block floating parameters for each band and a number of bits required to provide block floating parameters for each band up to the highest useable band. .Iaddend..Iadd.105. The apparatus for compressing a digital audio input signal of claim 103, wherein

the block floating parameters include a word length and a block floating coefficient,

the block floating means applies block floating in response to the block floating coefficient,

the quantizing means quantizes the spectral coefficients in response to the word length, and

the block floating parameters in block of data derived from the block of spectral coefficients comprise:

a main word length for each band up to the highest usable band,

a main block floating coefficient for each band up to the highest useable band, and

a reserve word length for each of the lower frequency bands. .Iaddend..Iadd.106. The apparatus for compressing a digital audio input signal of claim 105, wherein the block floating parameters in block of data derived from the block of spectral coefficients further comprises of a reserve block floating coefficient for each of the lower frequency

52. bands. .Iaddend..Iadd.107. The apparatus for compressing aft digital audio input signal of claim 105, wherein the adding means includes a means for arranging the quantized spectral coefficients sequentially in the block of data derived from the spectral coefficients, beginning with the quantized spectral coefficients in the lowest frequency band. .Iaddend..Iadd.108. The apparatus of claim 107, wherein the reserve word lengths comprise a reserve word length for each of a first number of lower frequency bands and wherein the block floating parameters in block of data derived from the block of spectral coefficients further comprise a reserve block floating coefficient for each of a second number of the lower frequency bands, the second number of the lower frequency bands being less than the first number of the lower frequency bands. .Iaddend..Iadd.109. An apparatus for decompressing a compressed digital signal, comprising:

an error detection circuit for generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands hither in frequency than the highest useable band;

a block floating coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

a word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.110. The apparatus of claim 109, wherein the inverse orthogonal transform circuit comprises;

an inverse modified discrete cosine transformer. .Iaddend..Iadd.111. The apparatus of claim 109, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.112. The apparatus of claim 109, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal.

53. Iaddend..Iadd.113. The apparatus of claim 112, wherein the plurality of synthesizers comprises:

a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.114. A method for decompressing a compressed digital signal, comprising the steps of;

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

36. separate one of a plurality of frequency ranges. .Iaddend..Iadd.41. The method of claim 40, further comprising the step of:

combining each of the inverse orthogonally transformed restored spectral coefficients to generate an output signal. .Iaddend..Iadd.42. The method of claim 41, wherein the step of combining comprises the step of;

inverse quadrature mirror filtering. .Iaddend..Iadd.43. An apparatus for decompressing a compressed digital signal, comprising;

an error detection circuit for generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, and

block floating parameters for each band up to the highest useable band;

a block floating coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

a word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain.

40. Iaddend..Iadd.54. The apparatus of claim 53, wherein the inverse orthogonal transform circuit comprises:

an inverse modified discrete cosine transformer. .Iaddend..Iadd.55. The apparatus of claim 53, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.56. The apparatus of claim 53, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal.

54. the time domain. .Iaddend..Iadd.115. The method of claim 114, wherein the step of transforming comprises the step of:

inverse orthogonally transforming. .Iaddend..Iadd.116. The method of claim 114, wherein the step of transforming comprises the steps of;

inverse orthogonal transforming restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.117. The method of claim 116, further comprising the steps of;

combining each of the inverse orthogonally transformed restored spectral coefficients to generate an output signal. .Iaddend..Iadd.118. The method of claim 117, wherein the step of combining comprises the step of;

inverse quadrature mirror filtering. .Iaddend..Iadd.119. An apparatus for decompressing a compressed digital signal, comprising;

an error detection circuit for generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, and

block floating parameters for each band up to the highest useable band;

a block floating coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

a word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.120. The apparatus of claim 119, wherein the inverse orthogonal transform circuit comprises;

an inverse modified discrete cosine transformer. .Iaddend..Iadd.121. The apparatus of claim 119, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.122. The apparatus of claim 119, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal.

55. Iaddend..Iadd.123. The apparatus of claim 122, wherein the plurality of synthesizers comprises:

a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.124. A method for decompressing a compressed digital signal, comprising the steps of;

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derided from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, and

block floating parameters for each band up to the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients, and

transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.125. The method of claim 124, wherein the step of transforming comprises the step of;

56. inverse orthogonally transforming. .Iaddend..Iadd.126. The method of claim 124, wherein the step of transforming comprises the steps of:

inverse orthogonal transforming restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.127. The method of claim 126, further comprising the steps of;

combining each of the inverse orthogonally transformed restored spectral coefficients to generate an output signal. .Iaddend..Iadd.128. The method of claim 127, wherein the step of combining comprises the step of;

inverse quadrature mirror filtering. .Iaddend..Iadd.129. An apparatus for decompressing a compressed digital signal, comprising;

a block floating coefficient reading circuit for reading from the compressed digital signal block floating coefficients of block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to highest usable band, there being a number of bands up to the highest usable band,

the block floating parameters being for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

a word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain.

41. Iaddend..Iadd.57. The apparatus of claim 56, wherein the plurality of synthesizers comprises:

a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.58. A method for decompressing a compressed digital signal, comprising the steps of;

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band, and data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.59. The method of claim 58, wherein the step of transforming comprises the step of;

57. Iaddend..Iadd.130. The apparatus of claim 129, wherein the inverse orthogonal transform circuit comprises:

an inverse modified discrete cosine transformer. .Iaddend..Iadd.131. The apparatus of claim 129, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.132. The apparatus of claim 129, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal. .Iaddend..Iadd.133. The apparatus of claim 132, wherein the plurality of synthesizers comprises;

a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.134. A method for decompressing a compressed digital signal, comprising the steps of;

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band, and data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

58. the time domain. .Iaddend..Iadd.135. The method of claim 134, wherein the step of transforming comprises the step of:

inverse orthogonally transforming. .Iaddend..Iadd.136. The method of claim 134, wherein the step of transforming comprises the steps of;

inverse orthogonal transforming restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.137. The method of claim 136, further comprising the steps of;

combining each of the inverse orthogonally transformed restored spectral

42. inverse orthogonally transforming. .Iaddend..Iadd.60. The method of claim 58, wherein the step of transforming comprises the step of:

inverse orthogonal transforming restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.61. The method of claim 60, further comprising the step of;

combining each of the inverse orthogonally transformed restored spectral coefficients to generate an output signal. .Iaddend..Iadd.62. The method of claim 61, wherein the stet) of combining comprises the step of;

inverse quadrature mirror filtering. .Iaddend..Iadd.63. An apparatus for decompressing a compressed digital signal, comprising;

a block floating coefficient reading circuit for reading from the compressed digital signal block floating coefficients of block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

the block floating parameters being for each band up to the highest useable band;

a word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.64. The apparatus of claim 63, wherein the inverse orthogonal transform circuit comprises;

an inverse modified discrete cosine transformer. .Iaddend..Iadd.65. The apparatus of claim 63, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.66. The apparatus of claim 63, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal. .Iaddend..Iadd.67. The apparatus of claim 66, wherein the plurality of synthesizers comprises;

a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.68. A method for decompressing a compressed digital signal, comprising the steps of;

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients consisting of

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

59. coefficients to generate an output signal. .Iaddend..Iadd.138. The method of claim 137, wherein the step of combining comprises the step of:

inverse quadrature mirror filtering. .Iaddend..Iadd.139. An apparatus for decompressing a compressed digital signal, comprising;

a block floating coefficient reading circuit for reading from the compressed digital signal block floating coefficients of block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

the block floating parameters being for each band up to the highest useable band;

word length reading circuit for reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

a quantized spectral coefficient reading circuit for reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

a spectral coefficient restoring circuit for generating restored spectral coefficient in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

an inverse orthogonal transform circuit for transforming the restored spectral coefficients into frames of samples in the time domain.

60. Iaddend..Iadd.140. The apparatus of claim 139, wherein the inverse orthogonal transform circuit comprises:

an inverse modified discrete cosine transformer. .Iaddend..Iadd.141. The apparatus of claim 139, wherein the inverse orthogonal transform circuit comprises;

a plurality of inverse orthogonal transform circuits, each inverse transform circuit operative to transform restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.142. The apparatus of claim 139, further comprising;

a plurality of synthesizers for combining outputs of each of the plurality of inverse orthogonal transform circuits to generate an output signal. .Iaddend..Iadd.143. The apparatus of claim 142, wherein the plurality of synthesizers comprises;

a plurality of inverse quadrature mirror filters. .Iaddend..Iadd.144. A method for decompressing a compressed digital signal, comprising the steps of;

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from, a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

61. the time domain. .Iaddend..Iadd.145. The method of claim 144, wherein the step of transforming comprises the step of:

inverse orthogonally transforming. .Iaddend..Iadd.146. The method of claim 144, wherein the step of transforming comprises the steps of;

inverse orthogonal transforming restored spectral coefficients in a separate one of a plurality of frequency ranges. .Iaddend..Iadd.147. The method of claim 146, further comprising the steps of;

combining each of the inverse orthogonally transformed restored spectral coefficients to generate an output signal. .Iaddend..Iadd.148. The method of claim 147, wherein the step of combining comprises the step of;

inverse quadrature mirror filtering. .Iaddend..Iadd.149. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method steps comprising;

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band,

block floating parameters for each band up to the highest useable band, and

data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands hither in frequency than the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

62. the time domain. .Iaddend..Iadd.150. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method steps comprising:

generating an error detection signal in response to both error correction codes appended to the compressed digital signal and a detection of errors in the compressed digital signal, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, and

block floating parameters for each band up to the highest useable band;

reading from the compressed digital signal, in response to the error detection signal, block floating coefficients of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal, word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the error detection signal and the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in

63. the time domain. .Iaddend..Iadd.151. A program storage device readable by a machine tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method steps comprising:

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band, and data indicating the number of bands up to the highest useable band, where zero bits are allocated to the spectral coefficients in bands higher in frequency than the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend..Iadd.152. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for decompressing a compressed digital signal, said method steps comprising;

reading from the compressed digital signal block floating coefficients of the block floating parameters, the compressed digital signal including a block of data derived from a block of spectral coefficients comprising

quantized spectral coefficients for each band up to a highest usable band, there being a number of bands up to the highest usable band, the block floating parameters being for each band up to the highest useable band;

reading from the compressed digital signal word lengths of the block floating parameters;

reading from the compressed digital signal, in response to the word lengths, the quantized spectral coefficients;

generating restored spectral coefficients in response to the block floating coefficients, word lengths and the quantized spectral coefficients; and

transforming the restored spectral coefficients into frames of samples in the time domain. .Iaddend.