Analysis filterbank, synthesis filterbank, encoder, de-coder, mixer and conferencing system
First Claim
1. Analysis filterbank for filtering a plurality of time-domain input frames of an audio signal, an input frame comprising a number of ordered input samples, comprising:
- a windower configured to generate a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples, wherein the windower is configured to process the plurality of input frames in an overlapping manner using a sample advance value,wherein the sample advance value is less than the number of ordered input samples of an input frame divided by 2; and
a time/frequency converter configured to provide an output frame comprising a number of output values, an output frame being a spectral representation of a windowed frame, wherein the windower or the time/frequency converter comprises a hardware implementation.
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Abstract
An embodiment of an analysis filterbank for filtering a plurality of time domain input frames, wherein an input frame comprises a number of ordered input samples, comprises a windower configured to generate a plurality of windowed frames, wherein a windowed frame comprises a plurality of windowed samples, wherein the windower is configured to process the plurality of input frames in an overlapping manner using a sample advance value, wherein the sample advance value is less than the number of ordered input samples of an input frame divided by two, and a time/frequency converter configured to provide an output frame comprising a number of output values, wherein an output frame is a spectral representation of a windowed frame.
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Citations
99 Claims
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1. Analysis filterbank for filtering a plurality of time-domain input frames of an audio signal, an input frame comprising a number of ordered input samples, comprising:
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a windower configured to generate a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples, wherein the windower is configured to process the plurality of input frames in an overlapping manner using a sample advance value, wherein the sample advance value is less than the number of ordered input samples of an input frame divided by 2; and a time/frequency converter configured to provide an output frame comprising a number of output values, an output frame being a spectral representation of a windowed frame, wherein the windower or the time/frequency converter comprises a hardware implementation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. Synthesis filterbank for filtering a plurality of input frames of an audio signal, each input frame comprising a number of ordered input values, comprising:
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a frequency/time converter configured to provide a plurality of output frames, an output frame comprising a number of ordered output samples, an output frame being a time representation of an input frame; a windower configured to generate a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples; and wherein the windower is configured to provide the plurality of windowed samples for a processing in an overlapping manner based on a sample advance value; an overlap/adder configured to provide an added frame comprising a start section and a remainder section, an added frame comprising a plurality of added samples by adding at least three windowed samples from at least three windowed frames for an added sample in the remainder section of an added frame and by adding at least two windowed samples from at least two different windowed frames for an added sample in the start section, wherein the number of windowed samples added to obtain an added sample in the remainder section is at least one sample higher compared to the number of windowed samples added to obtain an added sample in the start section, or wherein the windower is configured to disregard at least the earliest output value according to the order of the ordered output samples or to setting the corresponding windowed samples to a predetermined value or to at least a value in a predetermined range for each windowed frame of the plurality of windowed frames; and wherein the overlap/adder is configured to provide the added sample in the remainder section of an added frame based on at least three windowed samples from at least three different windowed frames and an added sample in the start section based on at least two windowed samples from at least two different windowed frames, wherein the frequency/time converter, the windower, or the overlap/adder comprises a hardware implementation. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73)
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74. Synthesis filterbank for filtering a plurality of input frames of an audio signal, each input frame comprising M ordered input values yk(0), . . . , yk(M−
- 1), wherein M is a positive integer, and wherein k is an integer indicating a frame index,
comprising; an inverse type-IV discrete cosine transform frequency/time converter configured to provide a plurality of output frames, an output frame comprising 2M ordered output samples xx(0), . . . , xk(2M−
1) based on the input values yk(0), . . . , yk(M−
1);a windower configured to generate a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples zk(0), . . . , zk(2M−
1) based on the equation
zk(n)=w(n)·
xk(n)
for n=0, . . . , 2M−
1,wherein n is an integer indicating a sample index, and wherein w(n) is a real-valued window function coefficient corresponding to the sample index n; an overlap/adder configured to provide an intermediate frame comprising a plurality of intermediate samples mk(0), . . . , mk(M−
1) based on the equation
mk(n)=zk(n)+zk-1(n+M)
for n=0, . . . , M−
1;and a lifter configured to provide an added frame comprising a plurality of added samples outk(0), . . . , outk(M−
1) based on the equation
outk(n)=mk(n)+l(n−
M/2)·
mk-1(M−
1−
n)
for n=M/2, . . . , M−
1
and
outk(n)=mk(n)+l(M−
1−
n)·
outk-1(M−
1−
n)
for n=0, . . . , M/2−
1,wherein l(0), . . . , l(M−
1) are real-valued lifting coefficients, wherein inverse type-IV discrete cosine transform frequency/time converter, the windower, the overlap/adder, or the lifter comprises a hardware implementation. - View Dependent Claims (75, 76, 77, 78)
- 1), wherein M is a positive integer, and wherein k is an integer indicating a frame index,
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79. Encoder comprising:
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an analysis filterbank for filtering a plurality of time-domain input frames, an input frame comprising a number of ordered input samples, comprising; a windower configured to generate a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples, wherein the windower is configured to process the plurality of input frames in an overlapping manner using a sample advance value, wherein the sample advance value is less than the number of ordered input samples of an input frame divided by 2; and a time/frequency converter configured to provide an output frame comprising a number of output values, an output frame being a spectral representation of a windowed frame, wherein the windower or the time/frequency converter comprises a hardware implementation. - View Dependent Claims (80)
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81. Audio decoder comprising:
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a synthesis filterbank for filtering a plurality of input frames, each input frame comprising a number of ordered input values, comprising; a frequency/time converter configured to provide a plurality of output frames, an output frame comprising a number of ordered output samples, an output frame being a time representation of an input frame; a windower configured to generate a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples; and wherein the windower is configured to provide the plurality of windowed samples for a processing in an overlapping manner based on a sample advance value; an overlap/adder configured to provide an added frame comprising a start section and a remainder section, an added frame comprising a plurality of added samples by adding at least three windowed samples from at least three windowed frames for an added sample in the remainder section of an added frame and by adding at least two windowed samples from at least two different windowed frames for an added sample in the start section, wherein the number of windowed samples added to obtain an added sample in the remainder section is at least one sample higher compared to the number of windowed samples added to obtain an added sample in the start section, or wherein the windower is configured to disregard at least the earliest output value according to the order of the ordered output samples or to setting the corresponding windowed samples to a predetermined value or to at least a value in a predetermined range for each windowed frame of the plurality of windowed frames; and wherein the overlap/adder is configured to provide the added sample in the remainder section of an added frame based on at least three windowed samples from at least three different windowed frames and an added sample in the start section based on at least two windowed samples from at least two different windowed frames, wherein the frequency/time converter, the windower, or the overlap/adder comprises a hardware implementation. - View Dependent Claims (82)
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83. Audio decoder comprising:
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a synthesis filterbank for filtering a plurality of input frames, each input frame comprising M ordered input values yk(0), . . . , yk(M−
1), wherein M is a positive integer, and wherein k is an integer indicating a frame index, comprising;an inverse type-IV discrete cosine transform frequency/time converter configured to provide a plurality of output frames, an output frame comprising 2M ordered output samples xk(0), . . . , xk(2M−
1) based on the input values yk(0), . . . , yk(M−
1);a windower configured to generate a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples zk(0), . . . , zk(2M−
1) based on the equation
zk(n)=w(n)·
xk(n)
for n=0, . . . , 2M−
1,wherein n is an integer indicating a sample index, and wherein w(n) is a real-valued window function coefficient corresponding to the sample index n; an overlap/adder configured to provide an intermediate frame comprising a plurality of intermediate samples mk(0), . . . , mk(M−
1) based on the equation
mk(n)=zk(n)+zk-1(n+M)
for n=0, . . . , M−
1;and a lifter configured to provide an added frame comprising a plurality of added samples outk(0), . . . , outk(M−
1) based on the equation
outk(n)=mk(n)+l(n−
M/2)·
mk-1(M−
1−
n)
for n=M/2, . . . , M−
1
and
outk(n)=mk(n)+l(M−
1−
n)·
outk-1(M−
1−
n)
for n=0, . . . , M/2−
1,wherein l(0), . . . , l(M−
1) are real-valued lifting coefficients, wherein inverse type-IV discrete cosine transform frequency/time converter, the windower, the overlap/adder, or the lifter comprises a hardware implementation. - View Dependent Claims (84)
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85. Mixer for mixing a plurality of input frames, each input frame being a spectral representation of a corresponding time-domain frame and each input frame of the plurality of input frames being provided from a different audio source, comprising:
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an entropy decoder configured to entropy decode the plurality of input frames; a scaler configured to scale the plurality of entropy decoded input frames in the frequency domain and configured to obtain a plurality of scaled frames in the frequency domain, each scaled frame corresponding to an entropy decoded input frame; an adder configured to add up the scaled frames in the frequency domain to generate an added frame in the frequency domain; and an entropy encoder configured to entropy encoding the added frame to obtain a mixed frame, wherein the entropy decoder, the scaler, the adder, or the entropy encoder comprises a hardware implementation. - View Dependent Claims (86, 87, 88, 89, 90, 91, 92)
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93. Conferencing system comprising:
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a mixer for mixing a plurality of input frames, each input frame being a spectral representation of a corresponding time-domain frame and each input frame of the plurality of input frames being provided from an audio different source, comprising; an entropy decoder configured to entropy decode the plurality of input frames; a scaler configured to scale the plurality of entropy decoded input frames in the frequency domain and configured to obtain a plurality of scaled frames in the frequency domain, each scaled frame corresponding to an entropy decoded input frame; an adder configured to add up the scaled frames in the frequency domain to generate an added frame in the frequency domain; and an entropy encoder configured to entropy encoding the added frame to obtain a mixed frame, wherein the entropy decoder, the scaler, the adder, or the entropy encoder comprises a hardware implementation.
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94. Method for filtering a plurality of time domain input frames of an audio signal, an input frame comprising a number of ordered input samples,
the method comprising: -
generating, performed by a windower, a plurality of windowed frames by processing the plurality of input frames in an overlapping manner using a sample advance value; wherein the sample advance value is less than the number of ordered input samples of an input frame divided by 2; and providing, performed by a time/frequency converter, a plurality of output frames comprising a number of output values by performing a time/frequency conversion, an output frame being a spectral representation of a windowed frame, wherein the windower or the time/frequency converter comprises a hardware implementation.
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95. Method for filtering a plurality of input frames of an audio signal, each input frame comprising a number of ordered input values,
the method comprising: -
performing, performed by a frequency/time converter, a frequency/time conversion and providing a plurality of output frames, an output frame comprising a number of ordered output samples, an output frame being a time representation of an input frame; generating, performed by a windower, a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples by processing the plurality of output samples for processing the windowed frames in an overlapping manner based on a sample advanced value; generating, performed by an overlap/adder, an added frame comprising a start section and a remainder section, wherein a added frame comprises an added sample by adding at least three windowed samples from at least three different windowed frames for an added sample in the remainder section of an added frame and an added sample by adding at least two windowed samples from at least two different windowed frames for an added sample in the start section, wherein the number of windowed samples added to obtain an added sample is in the remainder section at least one sample higher compared to the number of windowed samples added to obtain an added sample in the start section; or wherein generating the plurality of windowed frames comprises disregarding at least the earliest output sample according to the order of the ordered output sample or to setting the corresponding windowed sample to a predetermined value to at least a value in a predetermined range for each windowed frame of the plurality of windowed frames; and wherein providing an added frame comprises providing an added sample by adding at least three windowed samples from at least three different windowed frames for an added sample in the remainder section of an added frame and an added sample by adding at least two windowed samples from at least two different windowed frames for an added sample in the start section, wherein the frequency/time converter, the windower, or the overlap/adder comprises a hardware implementation.
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96. Method for filtering a plurality of input frames of an audio signal, each input frame comprising M ordered input values yk(0), . . . , yk(M−
- 1), wherein M is a positive integer, and wherein k is an integer indicating an index of the input frame,
the method comprising; performing, performed by an inverse type-IV discrete cosine transform/time converter, an inverse type-IV discrete cosine transform and providing a plurality of output frames xk(0), . . . , xk(2M−
1) based on the input values yk(0), . . . , yk(M−
1);generating, performed by a windower, a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples zk(0), . . . , zk(2M−
1) based on an equation
zk(n)=w(n)·
xk(n)
for n=0, . . . , 2M−
1,wherein n is an integer; generating, performed by an overlap/adder, a plurality of intermediate frames, each intermediate frame comprising a plurality of intermediate samples mk(0), . . . , mk(M−
1) based on the equation
mk(n)=zk(n)+zk-1(n+M)
for n=0, . . . , M−
1;and generating, performed by a lifter, a plurality of added frames comprising a plurality of added samples outk(0), . . . , outk(M) based on an equation
outk(n)=mk(n)+l(n−
M/2)·
mk-1(M−
1−
n)
for n=M/2, . . . , M−
1
and
outk(n)=mk(n)+l(M−
1−
n)·
outk-1(M−
1−
n)
for n32 0, . . . , M/2−
1,wherein w(0), . . . , w(2M−
1) are real-valued window coefficients;wherein l(0), . . . , l(M−
1) are real-valued lifting coefficients; andwherein inverse type-IV discrete cosine transform frequency/time converter, the windower, the overlap/adder, or the lifter comprises a hardware implementation.
- 1), wherein M is a positive integer, and wherein k is an integer indicating an index of the input frame,
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97. Non-transitory computer-readable medium having stored thereon a computer program for performing, when running on a computer, a method for filtering a plurality of time domain input frames of an audio signal, an input frame comprising a number of ordered input samples,
comprising: -
generating a plurality of windowed frames by processing the plurality of input frames in an overlapping manner using a sample advance value; wherein the sample advance value is less than the number of ordered input samples of an input frame divided by 2; and providing a plurality of output frames comprising a number of output values by performing a time/frequency conversion, an output frame being a spectral representation of a windowed frame.
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98. Non-transitory computer-readable medium having stored thereon a computer program for performing, when running on a computer, a method for filtering a plurality of input frames of an audio signal, each input frame comprising a number of ordered input values, comprising:
-
performing a frequency/time conversion and providing a plurality of output frames, an output frame comprising a number of ordered output samples, an output frame being a time representation of an input frame; generating a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples by processing the plurality of output samples for processing the windowed frames in an overlapping manner based on a sample advanced value; generating an added frame comprising a start section and a remainder section, wherein a added frame comprises an added sample by adding at least three windowed samples from at least three different windowed frames for an added sample in the remainder section of an added frame and an added sample by adding at least two windowed samples from at least two different windowed frames for an added sample in the start section, wherein the number of windowed samples added to obtain an added sample is in the remainder section at least one sample higher compared to the number of windowed samples added to obtain an added sample in the start section; or wherein generating the plurality of windowed frames comprises disregarding at least the earliest output sample according to the order of the ordered output sample or to setting the corresponding windowed sample to a predetermined value to at least a value in a predetermined range for each windowed frame of the plurality of windowed frames; and wherein providing an added frame comprises providing an added sample by adding at least three windowed samples from at least three different windowed frames for an added sample in the remainder section of an added frame and an added sample by adding at least two windowed samples from at least two different windowed frames for an added sample in the start section.
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99. Non-transitory computer-readable medium having stored thereon a computer program for performing, when running on a computer, a method for filtering a plurality of input frames of an audio signal, each input frame comprising M ordered input values yk(0), . . . , yk(M−
- 1), wherein M is a positive integer, and wherein k is an integer indicating an index of the input frame,
comprising; performing an inverse type-IV discrete cosine transform and providing a plurality of output frames xk(0), . . . , xk(2M−
1) based on the input values yk(0), . . . , yk(M−
1);generating a plurality of windowed frames, a windowed frame comprising a plurality of windowed samples zk(0), . . . , zk(2M−
1) based on an equation
zk(n)=w(n)·
xk(n)
for n=0, . . . , 2M−
1,wherein n is an integer; generating a plurality of intermediate frames, each intermediate frame comprising a plurality of intermediate samples mk(0), . . . , mk(M−
1) based on the equation
mk(n)=zk(n)+zk-1(n+M)
for n32 0, . . . , M−
1;and generating a plurality of added frames comprising a plurality of added samples outk(0), . . . , outk(M) based on an equation
outk(n)=mk(n)+l(n−
M/2)·
mk-1(M−
1−
n)
for n=M/2, . . . , M−
1
and
outk(n)=mk(n)+l(M−
1−
n)·
outk-1(M−
1−
n)
for n=0, . . . , M/2−
1,wherein w(0), . . . , w(2M−
1) are real-valued window coefficients; andwherein l(0), . . . , l(M−
1) are real-valued lifting coefficients.
- 1), wherein M is a positive integer, and wherein k is an integer indicating an index of the input frame,
Specification