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Claims  |
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What is claimed is:
1. In an encoder for encoding two or more audio channels, the combination
comprising:
subband means for generating subband signals, each subband signal
representing spectral energy in a respective subband of a respective one
of said audio channels,
composite means for forming one or more composite signals, each composite
signal formed by combining subband signals in a respective subband of two
or more of said audio channels, and
formatting means for assembling an output signal including information
representing said one or more composite signals in a form comprising a
coarse measure of composite signal contents and a corresponding finer
measure of composite signal contents, and including information conveying
spectral levels of each subband signal combined into a respective
composite signal.
2. The combination of claim 1 further comprising means for encoding said
one or more composite signals and subband signals not combined into a
respective composite signal, wherein said composite means forms said one
or more composite signals only when the amount of information required to
encode subband signals generated by said subband means exceeds a limit,
and wherein said composite signals are formed only to the extent that the
amount of information saved by encoding said composite signals rather than
the subband signals combined into said composite signals is sufficient to
allow encoding using amount of information which does not exceed said
limit.
3. The combination of claim 1 wherein said more finely quantized values are
quantized using bits allocated from a common pool of bits.
4. The combination of claim 1 further comprising means for adding, prior to
quantization, a noise-like signal to said subband signals and said one or
more composite signals.
5. The combination of claim 4 wherein the mean amplitude of said noise-like
signal substantially matches the expected quantizing error of said subband
signals and said one or more composite signals.
6. The combination of claim 1 wherein said information conveying spectral
levels for a respective composite signal includes an indication of
amplitude or power level of each constituent subband signal.
7. The combination of claim 6 wherein said indication of amplitude or power
level is either
a plurality of elements, each element representing the difference in
amplitude or power level between a respective constituent subband signal
and a level of said composite signal, or
a plurality of elements, each element representing the ratio of amplitude
or power level between a respective constituent subband signal and a level
of said composite signal, or
a plurality of elements, each element representing the absolute value of
the amplitude or power level of each respective constituent subband
signal.
8. The combination of claim 1 wherein said plurality of audio channels
represent a sound field and said information conveying spectral levels for
a respective composite signal includes sound field localization
information for constituent subband signals combined into the respective
composite signal.
9. The combination of claim 1 wherein said composite means includes means
for compensating out-of-phase signal components between subband signals
from which said one or more composite signals are formed.
10. The combination of claim 1 wherein said one or more composite signals
and the subband signals not represented by a respective composite signal
are represented in a form comprising one or more scale factors each
associated with one or more scaled values, the combination further
comprising means for adjusting either or both dynamic range and gain by
manipulating the values of said one or more scale factors.
11. The combination of claim 1 wherein said composite means includes
selection means for selecting each subband from which a respective one of
said one or more composite signals is formed.
12. The combination of claim 11 wherein said selection means selects one or
more predetermined subbands.
13. The combination of claim 11 wherein said selection means selects one or
more of the highest frequency subbands.
14. The combination of claim 11 wherein said selection means selects one or
more subbands such that the resulting one or more composite signals are
least likely to be subject to errors caused by out-of-phase signal
cancellation.
15. The combination of claim 11 further comprising means for allocating a
limited number of bits to said one or more composite signals and to
subband signals not represented by said one or more composite signals,
wherein said selection means selects subbands whose subband signals, if
not represented by a respective composite signal, would not be allocated a
respective minimum number of bits.
16. The combination of claim 15 wherein said respective minimum number of
bits is the number of bits required to render quantizing noise in a
respective subband substantially inaudible.
17. The combination of claim 11 wherein said selection means selects a
subband starting with subbands in which coding inaccuracies are least
objectionable.
18. The combination of claim 11 wherein said selection means selects the
highest frequency subband, reiteratively selecting the highest frequency
subband not already selected until sufficient bits are made available to
allocate at least said respective minimum number of bits to subband
signals not represented by a respective composite signal.
19. The combination of claim 11 wherein said means for selecting further
selects subband signals according to in which audio channels the subband
signals are located.
20. In a decoder for decoding an encoded signal generated by an encoder,
said encoded signal including subband information representing respective
subbands of a plurality of audio channels and including spectral level
information, each subband constituting a portion of the spectrum of said
audio channels, said subband information representing one or more
composite signals and a plurality of subband signals, each of said
composite signals formed in said encoder by combining subband signals of
two or more of said plurality of audio channels in a respective subband,
the combination in said decoder comprising:
deformatting means for obtaining said subband information and said spectral
level information from said encoded signal, wherein said subband
information is represented in a form comprising a coarse measure of
composite signal contents and a corresponding finer measure of composite
signal contents, and said spectral level information conveys spectral
levels of each subband signal combined in a respective composite signal,
reconstruction means for obtaining said one or more composite signals and
said plurality of subband signals in response to said subband information,
and for deriving subband signals in response to said one or more composite
signals and said spectral level information, and
synthesis means for generating a plurality of output signals in response to
said derived subband signals and said plurality of subband signals
obtained from said subband information.
21. The combination of claim 20 further comprising means for substituting a
noise-like signal for the least significant bits of said more finely
quantized values.
22. The combination of claim 20 wherein said more finely quantized values
include a noise-like signal added prior to their quantization in said
encoder, wherein said combination further comprises means for generating a
noise-like signal substantially the same as that added prior to
quantization, and means for subtracting said noise-like signal from said
more finely quantized values after dequantization.
23. The combination of claim 20 wherein said more finely quantized values
are dequantized using bits allocated from a common pool of bits.
24. The combination of claim 20 wherein said spectral level information
includes an indication of amplitude or power level of each constituent
subband signal combined into a respective composite signal.
25. The combination of claim 20 wherein said spectral level information
includes an indication of sound field localization for constituent subband
signals combined into a respective composite signal.
26. The combination of claim 20 further comprising means for inverse
out-of-phase compensation of signal components between subband signals
from which composite signals are formed.
27. The combination of claim 20 wherein said encoded signal comprises
subband information represented in a form comprising one or more scale
factors each associated with one or more scaled values, said combination
further comprising means for adjusting either or both dynamic range and
gain of said subband information by manipulating the values of said one or
more scale factors.
28. A method for use in the encoding of two or more audio channels,
comprising:
generating subband signals of said audio channels, each subband signal
representing spectral energy in a respective subband of a respective one
of said channels,
forming one or more composite signals, each composite signal formed by
combining subband signals in a respective subband of two or more of said
audio channels, and
assembling an output signal including information representing said one or
more composite signals in a form comprising a coarse measure of composite
signal contents and a corresponding finer measure of composite signal
contents, and including information conveying spectral levels of said
subband signal combined into a respective composite signal.
29. The method of claim 28 wherein said plurality of audio channels
represent a sound field and said information conveying spectral levels for
a respective composite signal includes sound field localization
information for constituent subband signal combined into the respective
composite signal.
30. The method of claim 28 wherein forming one or more composite signals
includes compensating out-of-phase signal components between subband
signal from which said one or more composite signals are formed.
31. The method of claim 28 wherein said one or more composite signals and
the subband signals not represented by a respective composite signal are
represented in a form comprising one or more scale factors each associated
with one or more scaled values, the method further comprising adjusting
either or both dynamic range and gain by manipulating the values of said
one or more scale factors.
32. The method of claim 28 further comprising encoding said one or more
composite signals and subband signals not combined into a respective
composite signal, wherein said one or more composite signals are formed
only when the amount of information required to encode subband signals
exceeds a limit, and wherein said composite signals are formed only to the
extent that the amount of information saved by encoding said composite
signals rather than the subband signals combined into said composite
signals is sufficient to allow encoding using amount of information which
does not exceed said limit.
33. The method of claim 28 wherein said more finely quantized values are
quantized using bits allocated from a common pool of bits.
34. The method of claim 28 wherein a noise-like signal is added to said
subband signal and said one or more composite signals prior to
quantization.
35. The method of claim 34 wherein the mean amplitude of said noise-like
signal substantially matches the expected quantizing error of said subband
signals and said one or more composite signals.
36. The method of claim 28 wherein said forming one or more composite
signals includes selecting each subband from which a respective one of
said one or more composite signals is formed.
37. The method of claim 36 wherein one or more predetermined subbands are
selected.
38. The method of claim 36 wherein one or more of the highest frequency
subbands are selected.
39. The method of claim 36 wherein one or more subbands are selected such
that the resulting one or more composite signals are least likely to be
subject to errors caused by out-of-phase signal cancellation.
40. The method of claim 36 further comprising allocating a limited number
of bits to said one or more composite signals and to subband signals not
represented by said one or more composite signals, wherein subbands are
selected whose subband signals, when not represented by a respective
composite signal, would not be allocated a respective minimum number of
bits.
41. The method of claim 40 wherein said respective minimum number of bits
is the number of bits required to render quantizing noise in a respective
subband substantially inaudible.
42. The method of claim 36 wherein a subband is selected starting with
subbands in which coding inaccuracies are least objectionable.
43. The method of claim 36 wherein the highest frequency subband is
selected, reiteratively selecting the highest frequency subband not
already selected until sufficient bits are made available to allocate at
least said respective minimum number of bits to subband signals not
represented by a respective composite signal.
44. The method of claim 36 wherein subband signals are selected according
to in which audio channels the subband signals are located.
45. The method of claim 28 wherein said information conveying spectra
levels for a respective composite signal includes an indication of the
amplitude or power level of said constituent subband signals.
46. The method of claim 45 wherein said indication of amplitude or power
level is either
a plurality of elements, each element representing the difference in
amplitude or power level between a respective constituent subband signal
and a level of said composite signal, or
a plurality of elements, each element representing the ratio of amplitude
or power level between a respective constituent subband signal and a level
of said composite signal, or
a plurality of elements, each element representing the absolute value of
the amplitude or power level of each respective constituent subband
signal.
47. A method for use in decoding an encoded signal generated by an encoder,
said encoded signal including subband information representing respective
subbands of a plurality of audio channels and including spectral level
information, each subband constituting a portion of the spectrum of said
audio channels, said subband information representing one or more
composite signals and a plurality of subband signals, each of said
composite signals formed in said encoder by combining subband signals of
two or more of said plurality of audio channels in a respective subband,
the method comprising:
obtaining said subband information and said spectral level information from
said encoded signal, wherein said subband information is represented in a
form comprising a coarse measure of composite signal contents and a
corresponding finer measure of composite signal contents, and said
spectral level information conveys spectral levels of each subband signal
combined in a respective composite signal,
obtaining said one or more composite signals and said plurality of subband
signals in response to said subband information, and for deriving subband
signals in response to said one or more composite signals and said
spectral level information, and
generating a plurality of output signals in response to said derived
subband signals and said plurality of subband signals obtained from said
subband information.
48. The method of claim 47 further comprises substituting a noise-like
signal for the least significant bits of said more finely quantized
values.
49. The method of claim 47 wherein said more finely quantized values
include a noise-like signal added prior to quantization in said encoder,
wherein said method further comprises generating a noise-like signal
substantially the same as that added prior to quantization, and
subtracting said noise-like signal from said more finely quantized values
after dequantization.
50. The method of claim 47 wherein said more finely quantized values are
dequantized using bits allocated from a common pool of bits.
51. The method of claim 47 wherein said spectral level information includes
an indication of amplitude or power level of each constituent subband
signal combined into a respective composite signal.
52. The method of claim 47 wherein said spectral level information includes
an indication of sound field localization for constituent subband signals
combined into a respective composite signal.
53. The method of claim 47 further comprising inverse out-of-phase
compensating of signal components between subband signals from which
composite signals are formed.
54. The method of claim 47 wherein said encoded signal comprises subband
information represented in a form comprising one or more scale factors
each associated with one or more scaled values, said method further
comprising adjusting either or both dynamic range and gain of said subband
information by manipulating the values of said one or more scale factors.
55. In an encoder for encoding two or more audio channels, the combination
comprising:
subband means for generating subband signals, each subband signal
representing spectral energy in a respective subband of a respective one
of said audio channels,
composite means for forming one or more composite signals, each composite
signal formed by combining subband signals in a respective subband of two
or more of said audio channels, wherein said composite means includes
means for compensating out-of-phase signal components between subband
signals from which said one or more composite signals are formed, and
formatting means for assembling an output signal including information
representing said one or more composite signals and subband signals not
combined into a respective composite signal.
56. The combination of claim 55 further comprising means for encoding said
one or more composite signals and subband signals not combined into a
respective composite signal, wherein said composite means forms said one
or more composite signals only when the amount of information required to
encode subband signals generated by said subband means exceeds a limit,
and wherein said composite signals are formed only to the extent that the
amount of information saved by encoding said composite signals rather than
the subband signals combined into said composite signals is sufficient to
allow encoding using amount of information which does not exceed said
limit.
57. The combination of claim 55 or 56 wherein said composite means includes
selection means for selecting each subband from which a respective one of
said one or more composite signals is formed.
58. The combination of claim 57 wherein said selection means selects a
subband starting with subbands in which coding inaccuracies are least
objectionable.
59. The combination of claim 57 wherein said means for selecting further
selects subband signals according to which audio channels the subband
signals are located.
60. The combination of claim 55 wherein said information conveying spectral
levels for a respective composite signal includes an indication of
amplitude or power level of each constituent subband signal.
61. The combination of claim 60 wherein said indication of amplitude or
power level is either
a plurality of elements, each element representing the difference in
amplitude or power level between a respective constituent subband signal
and a level of said composite signal, or
a plurality of elements, each element representing the ratio of amplitude
or power level between a respective constituent subband signal and a level
of said composite signal, or
a plurality of elements, each element representing the absolute value of
the amplitude or power level of each respective constituent subband
signal.
62. The combination of claim 55, 56 or 60 wherein said one or more
composite signals and the subband signals not represented by a respective
composite signal are represented in a form comprising one or more scale
factors each associated with one or more scaled values, the combination
further comprising means for adjusting either or both dynamic range and
gain by manipulating the values of said one or more scale factors.
63. A method for encoding two or more audio channels comprising:
generating subband signals, each subband signal representing spectral
energy in a respective subband of a respective one of said audio channels,
forming one or more composite signals, each composite signal formed by
combining subband signals in a respective subband of two or more of said
audio channels, wherein said combining includes compensating out-of-phase
signal components between subband signals from which said one or more
composite signals are formed, and
assembling an output signal including information representing said one or
more composite signals and subband signals not combined into a respective
composite signal.
64. The method of claim 63 further comprising encoding said one or more
composite signals and subband signals not combined into a respective
composite signal, wherein said one or more composite signals are formed
only when the amount of information required to encode said subband
signals exceeds a limit, and wherein said composite signals are formed
only to the extent that the amount of information saved by encoding said
composite signals rather than the subband signals combined into said
composite signals is sufficient to allow encoding using amount of
information which does not exceed said limit.
65. The method of claim 63 wherein said information conveying spectral
levels for a respective composite signal includes an indication of
amplitude or power level of each constituent subband signal.
66. The method of claim 65 wherein said indication of amplitude or power
level is either
a plurality of elements, each element representing the difference in
amplitude or power level between a respective constituent subband signal
and a level of said composite signal, or
a plurality of elements, each element representing the ratio of amplitude
or power level between a respective constituent subband signal and a level
of said composite signal, or
a plurality of elements, each element representing the absolute value of
the amplitude or power level of each respective constituent subband
signal.
67. The method of claim 63 or 64 wherein said combining includes selecting
each subband from which a respective one of said one or more composite
signals is formed.
68. The method of claim 67 wherein said selecting selects a subband
starting with subbands in which coding inaccuracies are least
objectionable.
69. The method of claim 67 wherein said selecting selects subband signals
according to in which audio channels the subband signals are located.
70. The method of claim 63, 64 or 65 wherein said one or more composite
signals and the subband signals not represented by a respective composite
signal are represented in a form comprising one or more scale factors each
associated with one or more scaled values, the method further comprising
adjusting either or both dynamic range and gain by manipulating the values
of said one or more scale factors. |
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Claims |
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