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Claims  |
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We claim:
1. An encoding system for encoding a digital signal having a specific
sampling frequency and bandwidth, comprising:
splitter means for dividing the bandwidth of the digital signal into M
successive subbands, and generating, in response to the digital signal, M
subband signals having reduced sampling frequencies, each of the subband
signals being associated with one of the subbands;
quantizing means for quantizing time-equivalent signal blocks of the
subband signals, a subband signal SB.sub.m of the subband signals having
successive signal blocks which each contain q samples of that subband
signal, each sample in a signal block of subband signal SB.sub.m having an
amplitude and being quantized by n.sub.m bits, where n.sub.m may vary for
different signal blocks of subband signal SB.sub.m ;
bit need determining means for determining bit needs for the
time-equivalent signal blocks, said bit need determining means comprising:
(a) means for estimating power within the time-equivalent signal blocks,
the signal block of subband signal SB.sub.m having a power v.sub.m ;
(b) means for determining scale factors for the time-equivalent signal
blocks, a scale factor SF.sub.m for the signal block of subband signal
SB.sub.m being determined from a sample therein having a maximum absolute
amplitude value;
(c) means for determining masking magnitudes for the time-equivalent signal
blocks, the signal block of subband signal SB.sub.m having a masking
magnitude w.sub.m which is determined in accordance with the following
relationship:
##EQU8##
where d.sub.mi v.sub.i denotes masked power in the signal block of subband
signal SB.sub.m as a result of power v.sub.i in a time-equivalent signal
block of a subband signal SB.sub.i of the subband signals, d.sub.mi
denotes a matrix coefficient in an M.times.M matrix by which the power
v.sub.i is multiplied to determine the masked power in the signal block of
subband signal SB.sub.m as a result of the time-equivalent signal block of
subband signal SB.sub.i, and w.sub.r.m denotes a masking threshold in the
signal block of subband signal SB.sub.m ; and
(d) means for determining the following relationship for the
time-equivalent signal blocks:
##EQU9##
where K.sub.1, K.sub.2 and K.sub.3 are constants; and b.sub.m is a bit
need for the signal block of subband signal SB.sub.m corresponding to the
number of bits by which the q samples in that signal block should be
represented, and b.sub.m may vary for different signal blocks of the
subband signal SB.sub.m ; and
bit allocation means for allocating bits to the time-equivalent signal
blocks from an available number of bits B, n.sub.m bits being allocated to
each of the q samples of the signal block of subband signal SB.sub.m in
accordance with at least the bit need, b.sub.m, for that signal block;
wherein M, m and i are integers such that 1.ltoreq.m.ltoreq.M and
1.ltoreq.i.ltoreq.M; q and B are integers, where q is greater than unity
and B is greater than zero; and b.sub.m, n.sub.m, v.sub.m, v.sub.i,
SF.sub.m, w.sub.m, d.sub.mi and w.sub.r.m are variables, where n.sub.m and
SF.sub.m are greater than or equal to zero.
2. The encoding system as claimed in claim 1, wherein K.sub.1 =1, K.sub.2
=1/.sqroot.3 and K.sub.3 is preferably equal to either 1 or zero.
3. The encoding system as claimed in claim 2, wherein said means for
estimating power estimates the power v.sub.m in the signal block of
subband signal SB.sub.m according to the following relationship:
##EQU10##
where s.sub.j is the amplitude of a jth sample in that signal block, j
being an integer such that 1.ltoreq.j.ltoreq.q and s.sub.j being a
variable.
4. The encoding system as claimed in claim 1, wherein said means for
estimating power estimates the power v.sub.m in the signal block of
subband signal SB.sub.m according to the following relationship:
##EQU11##
where s.sub.j is the amplitude of a jth sample in that signal block, j
being an integer such that 1.ltoreq.j.ltoreq.q and s.sub.j being a
variable.
5. The encoding systems as claimed in claim 1, wherein said bit need
determining means utilizes a logarithmic representation for d.sub.mi,
v.sub.i, w.sub.m and w.sub.r.m when determining the masking magnitude
w.sub.m.
6. The encoding system as claimed in claim 5, wherein K.sub.1 =1, K.sub.2
=1/.sqroot.3 and K.sub.3 is preferably equal to either 1 or zero.
7. The encoding system as claimed in claim 6, wherein said means for
estimating power estimates the power v.sub.m in the signal block of
subband signal SB.sub.m according to the following relationship:
##EQU12##
where s.sub.j is the amplitude of a jth sample in that signal block, j
being an integer such that 1.ltoreq.j.ltoreq.q and s.sub.j being a
variable.
8. The encoding system as claimed in claim 5, wherein said means for
estimating power estimates the power v.sub.m in the signal block of
subband signal SB.sub.m according to the following relationship:
##EQU13##
where s.sub.j is the amplitude of a jth sample in that signal block, j
being an integer such that 1.ltoreq.j.ltoreq.q and s.sub.j being a
variable.
9. The encoding system as claimed in claim 5, wherein said bit need
determining means further comprises means for adding and multiplying
logarithmically represented values.
10. The encoding system as claimed in claim 1, further comprising signal
formatting means for assembling into a frame of an output digital signal
having successive frames the q samples from the time-equivalent signal
blocks of the subband signals which have been quantized by said quantizing
means, scale factor information being included in the frame in the form of
x-bit words representing the scale factors associated with the
time-equivalent signal blocks for which the q samples are included in the
frame.
11. A transmitter, comprising the encoding system of claim 1.
12. The transmitter as claimed in claim 11, further comprising signal
formatting means for assembling into a frame of an output digital signal
having successive frames the q samples from the time-equivalent signal
blocks of the subband signals which have been quantized by said quantizing
means, scale factor information being included in the frame in the form of
x-bit words representing the scale factors associated with the
time-equivalent signal blocks for which the q samples are included in the
frame.
13. The transmitter as claimed in claim 12, further comprising a recording
means for recording the output digital signal in a track on a record
carrier.
14. The transmitter as claimed in claim 13, wherein the record carrier is a
magnetic record carrier.
15. A method of encoding a digital signal having a specific sampling
frequency and bandwidth, comprising:
dividing the bandwidth of the digital signal into M successive subbands,
and generating, in response to the digital signal, M subband signals
having reduced sampling frequencies, each of the subband signals being
associated with one of the subbands;
quantizing time-equivalent signal blocks of the subband signals, a subband
signal SBm of the subband signals having successive signal blocks which
each contain q samples of that subband signal, each sample in a signal
block of subband signal SB.sub.m having an amplitude and being quantized
by n.sub.m bits, where n.sub.m may vary for different signal blocks of
subband signal SB.sub.m ;
wherein in order to quantize the time-equivalent signal blocks, the
following steps are performed:
determining bit needs for the time-equivalent signal blocks by:
(a) estimating power within the time-equivalent signal blocks, the signal
block of subband signal SB.sub.m having a power v.sub.m ;
(b) determining scale factors for the time-equivalent signal blocks, a
scale factor SF.sub.m for the signal block of subband signal SB.sub.m
being determined from a sample therein which has a maximum absolute
amplitude value;
(c) determining masking magnitudes for the time-equivalent signal blocks,
the signal block of subband signal SB.sub.m having a masking magnitude
w.sub.m which is determined in accordance with the following relationship:
##EQU14##
where d.sub.mi v.sub.i denotes masked power in the signal block of subband
signal SB.sub.m as a result of power v.sub.i in a time-equivalent signal
block of a subband signal SB.sub.i of the subband signals, d.sub.mi
denotes a matrix coefficient in an M.times.M matrix by which the power
v.sub.i is multiplied to determine the masked power in the signal block of
subband signal SB.sub.m as a result of the time-equivalent signal block of
subband signal SB.sub.i, and w.sub.r.m denotes a masking threshold in the
signal block of subband signal SB.sub.m ; and
(d) determining the following relationship for the time-equivalent signal
blocks of the subband signals:
##EQU15##
where K.sub.1, K.sub.2 and K.sub.3 are constants; and b.sub.m is a bit
need for the signal block of subband signal SB.sub.m corresponding to the
number of bits by which the q samples in that signal block should be
represented, and b.sub.m may vary for different signal blocks of subband
signal SB.sub.m ; and
allocating bits to the time-equivalent signal blocks from an available
number of bits B, n.sub.m bits being allocated each of the q samples of
the signal block of subband signal SB.sub.m in accordance with the bit
need b.sub.m for that signal block;
wherein M, m and i are integers such that 1.ltoreq.m.ltoreq.M and
1.ltoreq.i.ltoreq.M; q and B are integers, where q is greater than unit
and B is greater than zero; and b.sub.m, n.sub.m, v.sub.m, v.sub.i,
SF.sub.m, w.sub.m, d.sub.mi and w.sub.r.m are variables, where n.sub.m and
SF.sub.m are greater than or equal to zero.
16. The method as claimed in claim 15, wherein in determining the masking
magnitude w.sub.m a logarithmic representation is used for d.sub.mi,
v.sub.i, w.sub.m and w.sub.r.m.
17. The method as claimed in claim 15, wherein K.sub.1 =1, K.sub.2
=1/.sqroot.3 and K.sub.3 is preferably equal to either 1 or zero.
18. The method as claimed in claim 11, wherein the power v.sub.m in the
signal block of subband signal SB.sub.m is estimated in accordance with
following relationship:
##EQU16##
where s.sub.j is the amplitude of a jth sample in that signal block, j
being an integer such that 1.ltoreq.j.ltoreq.q and s.sub.j being a
variable.
19. The method as claimed in claim 15, further comprising the step of
assembling into a frame of an output digital signal having successive
frame the q samples from the time-equivalent signal blocks of the subband
signals which have been quantized, scale factor information being included
in the frame in the form of x-bit words representing the scale factors
associated with the time-equivalent signal blocks for which the q samples
are included in the frame.
20. The method as claimed in claim 19, further comprising the recording the
output digital signal in a track on a record carrier.
21. The method as claimed in claim 20, wherein the record carrier is a
magnetic record carrier.
22. An encoding system for encoding a digital signal, comprising:
means for dividing the digital signal into a plurality of subband signals,
each of the subband signals having a plurality of signal blocks, each
containing q samples of that subband signal, where q is a positive
integer, which are successive in time, each of the signal blocks of a
subband signal being time-equivalent with a corresponding signal block of
each of the other subband signals, corresponding signal blocks of the
subband signals constituting time-equivalent signal blocks;
means for quantizing each of the q samples of each of the time-equivalent
signal blocks with n.sub.m bits, where n.sub.m is a variable greater than
or equal to zero which may vary for the time-equivalent signal blocks
and/or different signal blocks within the same subband signal and m is a
positive integer denoting which one of the subband signals a signal block
comes from;
bit determining means for determining a bit need b.sub.m for each of the
time-equivalent signal blocks, where b.sub.m is a variable which may vary
for the time-equivalent signal blocks and/or different signal blocks
within the same subband signal, the bit need b.sub.m for each of the
time-equivalent signal blocks corresponding to the number of bits by which
the q samples in that signal block should be represented and being
determined on the basis of a scale factor for that signal block, a linear
combination of each masked power in that signal block resulting from power
in each of the time-equivalent signals blocks and a masking threshold for
that signal block; and
means for allocating, from an available number of bits B, where B is a
positive integer, the n.sub.m bits to each of the q samples of each of the
time-equivalent signal blocks in accordance with the bit need b.sub.m for
each of the time-equivalent signal blocks.
23. The encoding system as claimed in claim 22, wherein said bit need
determining means comprises:
estimation means for estimating the power within each of the
time-equivalent signal blocks;
first determining means for determining the scale factor for each of the
time-equivalent signal blocks:
second determining means for determining a masking magnitude for each of
the time-equivalent signal blocks, the masking magnitude for a signal
block being determined based on the masked power in the signal block as a
result of the power in each of the time-equivalent signals blocks and the
masking threshold for the signal block; and
third determining means for determining the bit need b.sub.m for each of
the time-equivalent signal blocks.
24. The encoding system as claimed in claim 23, wherein said estimation
means estimates the power in a signal block in accordance with the
following relationship:
##EQU17##
where v.sub.m is a variable denoting the power in a signal block and
s.sub.j is variable denoting the amplitude of a jth sample in the signal
block, j being an integer such that 1.ltoreq.j.ltoreq.q.
25. The encoding systems as claimed in claim 23, wherein said first
determining means determines the scale factor for a signal block from a
sample therein having a maximum absolute amplitude value.
26. The encoding systems as claimed in claim 23, wherein said second
determining means determines the masking magnitude for a signal block in
accordance with the following relationship:
##EQU18##
where w.sub.m is a variable denoting the masking magnitude for the signal
block, M is a positive integer equal to the number of subband signals,
each of which are denoted by i, which is a positive integer such that
1.ltoreq.i.ltoreq.M, d.sub.mi v.sub.i is the masked power in the signal
block as a result of power v.sub.i, where v.sub.i is variable, in one of
the time-equivalent signal blocks, which time-equivalent signal block is
from subband signal i, d.sub.mi is variable denoting a matrix coefficient
in an M.times.M matrix by which the power v.sub.i is multiplied to
determine the masked power in the signal block as a result of the
time-equivalent signal block from subband signal i, and w.sub.r.m is a
variable denoting the masking threshold in the signal block.
27. The encoding system as claimed in claim 23, wherein said third
determining means determines the bits need b.sub.m for a signal block in
accordance with the following relationship:
##EQU19##
where K.sub.1, K.sub.2 and K.sub.3 are constants, SF.sub.m is a variable
denoting the scale factor for the signal block and wm is a variable
denoting the masking magnitude for the signal block.
28. The encoding system as claimed in claim 22, further comprising signal
formatting means for assembling into a frame of an output digital signal
having successive frames the q samples from the time-equivalent signal
blocks which have been quantized, scale factor information being included
in the frame in the form of x-bit words representing the scale factors
associated with the time-equivalent signal blocks for which the q samples
are included in the frame.
29. A transmitter, comprising the encoding system of claim 28.
30. The transmitter as claimed in claim 29, further comprising a recording
means for recording the output signal in a track of a record carrier.
31. A transmitter, comprising the encoding system of claim 22.
32. The encoding systems as claimed in claim 22, wherein the subband
signals have reduced sampling frequencies as compared to the digital
signal.
33. A method for encoding a digital signal, comprising:
dividing the digital signal into a plurality of subband signals, each of
the subband signals having a plurality of signal blocks, each containing q
samples of that subband signal, where q is a positive integer, which are
successive in time, each of the signal blocks of a subband signal being
time-equivalent with a corresponding signal block of each of the other
subband signals, corresponding signal blocks of the subband signals
constituting time-equivalent signal blocks; and
quantizing each of the q samples of each of the time-equivalent signal
blocks with n.sub.m bits, where n.sub.m is a variable greater than or
equal to zero which may vary for the time-equivalent signal blocks and/or
different signal blocks within the same subband signal and m is a positive
integer denoting which one of the subband signals a signal block comes
from;
wherein in order to quantize each of the time-equivalent signal blocks, the
following additional steps are preformed:
determining a bit need b.sub.m for each of the time-equivalent signal
blocks, where b.sub.m is a variable which may vary for the time-equivalent
signal blocks and/or different signal blocks within the same subband
signal, the bit need b.sub.m for each of the time-equivalent signal blocks
corresponding to the number of bits by which the q samples in that signal
block should be represented and being determined on the basis of a scale
factor for that signal block, a linear combination of each masked power in
that signal block resulting from power in each of the time-equivalent
signals blocks and a masking threshold for that signal block; and
allocating, from an available number of bits B, where B is a positive
integer, the n.sub.m bits to each of the q samples of each of the
time-equivalent signal blocks in accordance with the bit need b.sub.m for
each of the time-equivalent signal blocks.
34. The method as claimed in claim 33, wherein determining the bit need
b.sub.m for each of the time-equivalent signal blocks includes:
estimating the power within each of the time-equivalent signal blocks;
determining the scale factor for each of the time-equivalent signal blocks;
and
determining a masking magnitude for each of the time-equivalent signal
blocks, the masking magnitude for a signal block being determined based on
the masked power in the signal block as a result of the power in each of
the time-equivalent signals blocks and the masking threshold for the
signal block.
35. The method as claimed in claim 34, wherein the power in a signal block
is estimated in accordance with the following relationship:
##EQU20##
where v.sub.m is a variable denoting the power in a signal block and
s.sub.j is variable denoting the amplitude of a jth sample in the signal
block, j being an integer such that 1.ltoreq.j.ltoreq.q.
36. The method as claimed in claim 34, wherein the scale factor for a
signal block is determined from a sample therein having a maximum absolute
amplitude value.
37. The method as claimed in claim 34, wherein the masking magnitude for a
signal block is determined in accordance with the following relationship:
##EQU21##
where w.sub.m is a variable denoting the masking magnitude for the signal
block, M is a positive integer equal to the number of subband signals,
each of which are denoted by i, which is a positive integer such that
1.ltoreq.i.ltoreq.M, d.sub.mi v.sub.i is the masked power in the signal
block as a result of power v.sub.i, where v.sub.i is variable, in one of
the time-equivalent signal blocks, which time-equivalent signal block is
from subband signal i, d.sub.mi is variable denoting a matrix coefficient
in an M.times.M matrix by which the power v.sub.i is multiplied to
determine the masked power in the signal block as a result of the
time-equivalent signal block from subband signal i, and w.sub.r.m is a
variable denoting the masking threshold in the signal block.
38. The method as claimed in claim 34, further comprising assembling into a
frame of an output digital signal having successive frames the q samples
from the time-equivalent signal blocks which have been quantized, scale
factor information being included in the frame in the form of x-bit words
representing the scale factors associated with the time-equivalent signal
blocks for which the q samples are included in the frame.
39. The method as claimed in claim 33, wherein the bit need b.sub.m for a
signal block is determined in accordance with the following relationship:
##EQU22##
where K.sub.1, K.sub.2 and K.sub.3 are constants, SF.sub.m is a variable
denoting the scale factor for the signal block and wm is a variable
denoting a masking magnitude for the signal block, the masking magnitude
being a function of each masked power in the signal block resulting from
power in each of the time-equivalent signals blocks and the masking
threshold for the signal block.
40. A bit need determining device for determining bits needs for
time-equivalent signal blocks of subband signals, the device comprising:
means for estimating power within each of the time-equivalent signal
blocks;
means for determining a scale factor for each of the time-equivalent signal
blocks;
means for determining a masking magnitude for each of the time-equivalent
signal blocks, the masking magnitude for a time-equivalent signal block
being determined based on a linear combination of each masked power in the
time-equivalent signal block resulting from the power in each of the
time-equivalent signals blocks and a masking threshold for the
time-equivalent signal block; and
means for determining a bit need b.sub.m for each of the time equivalent
signal blocks, the bit need b.sub.m for a time-equivalent signal block
being determined based upon the scale factor and the masking magnitude for
the time-equivalent signal block.
41. A bit need determining device for determining bit needs for
time-equivalent signal blocks of M subband signals, each of the
time-equivalent signal blocks having q samples, where q is a positive
integer, the device comprising:
means for estimating power within the time-equivalent signal blocks, the
power within a time-equivalent signal block being denoted v.sub.m, where
v.sub.m is a variable, and m is a positive integer, such that
1.ltoreq.m.ltoreq.M, denoting which one of subband signals the
time-equivalent signal block comes from;
means for determining scale factors for the time-equivalent signal blocks,
a scale factor SF.sub.m, where SF.sub.m is a variable greater than or
equal to zero, for a time-equivalent signal block being determined from a
sample therein having a maximum absolute amplitude value;
means for determining masking magnitudes for the time-equivalent signal
blocks, a time-equivalent signal block having a masking magnitude w.sub.m,
where w.sub.m is a variable, which is determined in accordance with the
following relationship:
##EQU23##
where i is a positive integer, such that 1.ltoreq.i.ltoreq.M, denoting one
of the subband signals, d.sub.mi v.sub.i denotes masked power in the
time-equivalent signal block as a result of power v.sub.i, where v.sub.i
is variable, in one of the time-equivalent signal blocks, which is from
subband signal i, d.sub.mi is variable denoting a matrix coefficient in an
M.times.M matrix by which the power v.sub.i is multiplied to determine the
masked power in the time-equivalent signal block as a result of the one of
the time-equivalent signal blocks from subband signal i, and w.sub.r.m is
a variable denoting the masking threshold in the signal block; and
means for determining the bit need b.sub.m for the time-equivalent signal
block, the bit need bm for a time-equivalent signal block being determined
in accordance with the following relationship:
##EQU24##
where K.sub.1, K.sub.2 and K.sub.3 are constants.
42. The bit need determining device as claimed in claim 41, wherein K.sub.1
=1, K.sub.2 =1/.sqroot.3 and K.sub.3 is preferably equal to either 1 or
zero.
43. The bit need determining device as claimed in claim 41, wherein said
means for estimating power estimates the power v.sub.m in the
time-equivalent signal block according to the following relationship:
##EQU25##
where S.sub.j is variable denoting the amplitude of a jth sample in the
time-equivalent signal block, j being an integer such that
1.ltoreq.j.ltoreq.q.
44. The bit need determining device as claimed in claim 41, wherein said
bit need determining means utilizes a logarithmic representation for the
values of d.sub.mi, v.sub.i, w.sub.m and w.sub.r.m when determining the
masking magnitude for the time-equivalent signal block.
45. The bit need determining device as claimed in claim 44, further
comprising means for adding and multiplying the logarithmically
represented values.
46. A transmitter, comprising the bit need determining device claimed in
claim 41.
47. A method for determining bits needs for time-equivalent signal blocks
of subband signals, the device comprising:
estimating power within each of the time-equivalent signal blocks;
determining a scale factor for each of the time-equivalent signal blocks;
determining a masking magnitude for each of the time-equivalent signal
blocks, the masking magnitude for a time-equivalent signal block being
determined based on each masked power in the time-equivalent signal block
resulting from the power in each of the time-equivalent signals blocks and
a masking threshold for the time-equivalent signal block; and
determining a bit need b.sub.m for each of the time equivalent signal
blocks, the bit need b.sub.m for a time-equivalent signal block being
determined based upon the scale factor and the masking magnitude for the
time-equivalent signal block.
48. A method for determining bit needs for time-equivalent signal blocks of
M subband signals, each of the time-equivalent signal blocks having q
samples, where q is a positive integer, the device comprising:
estimating power within the time-equivalent signal blocks, the power within
a time-equivalent signal block being denoted v.sub.m, where v.sub.m is a
variable, and m is a positive integer, such that 1.ltoreq.m.ltoreq.M,
denoting which one of subband signals the time-equivalent signal block
comes from;
determining scale factors for the time-equivalent signal blocks, a scale
factor SF.sub.m, where SF.sub.m is a variable greater than or equal to
zero, for a time-equivalent signal block being determined from a sample
therein having a maximum absolute amplitude value;
determining masking magnitudes for the time-equivalent signal blocks, a
time-equivalent signal block having a masking magnitude w.sub.m, where
w.sub.m is a variable, which is determined in accordance with the
following relationship:
##EQU26##
where i is a positive integer, such that 1.ltoreq.i.ltoreq.M, denoting one
of the subband signals, d.sub.mi v.sub.i denotes masked power in the
time-equivalent signal block as a result of power v.sub.i, where v.sub.i
is variable, in one of the time-equivalent signal blocks, which is from
subband signal i, d.sub.mi is variable denoting a matrix coefficient in an
M.times.M matrix by which the power v.sub.i is multiplied to determine the
masked power in the time-equivalent signal block as a result of the one of
the time-equivalent signal blocks from subband signal i, and w.sub.r.m is
a variable denoting the masking threshold in the signal block; and
determining the bit need b.sub.m for the time-equivalent signal block, the
bit need bm for a time-equivalent signal block being determined in
accordance with the following relationship:
##EQU27##
where K.sub.1, K.sub.2 and K.sub.3 are constants.
49. The method as claimed in claim 48, wherein K.sub.1 =1, K.sub.2
=1/.sqroot.3 and K.sub.3 is preferably equal to either 1 or zero.
50. The method as claimed in claim 48, wherein the power v.sub.m in the
time-equivalent signal block is estimated according to the following
relationship:
##EQU28##
where s.sub.j is variable denoting the amplitude of a jth sample in the
time-equivalent signal block, j being an integer such that
1.ltoreq.j.ltoreq.q.
51. The method as claimed in claim 48, wherein a logarithmic representation
for the values of d.sub.mi, v.sub.i, w.sub.m and w.sub.r.m are utilized in
determining the masking magnitude for the time-equivalent signal block. |
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Claims |
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