Audio spatial environment engine using a single fine structure
A system for compensating for signal fade in a frequency-modulated transmission system is provided, such as for use in terrestrial frequency modulated receivers. The system includes a time domain to frequency domain conversion stage receiving M channels of audio data and generating a plurality of sub-bands of audio spatial image data. A sub-band vector calculation system receives the M channels of the plurality of sub-bands of audio spatial image data and generates image map data. A summation stage receives the M channels of the plurality of sub-bands of audio spatial image data and adds each of the corresponding sub-bands for each of the M channels to form a plurality of sub-band fine structures. A filter stage receives the plurality of sub-band fine structures and the image map data and multiplies the sub-band fine structures by a predetermined gain based on the image map data.
1 . A system for compensating for signal fade in a frequency-modulated transmission system comprising:
a time domain to frequency domain conversion stage receiving M channels of audio data and generating a plurality of sub-bands of audio spatial image data;
a sub-band vector calculation system receiving the M channels of the plurality of sub-bands of audio spatial image data and generating image map data;
a summation stage receiving the M channels of the plurality of sub-bands of audio spatial image data and adding each of the corresponding sub-bands for each of the M channels to form a plurality of sub-band fine structures; and
a filter stage receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined gain based on the image map data.
2 . The system of claim 1 wherein the sub-band vector calculation system generates X-axis position data x on the image map in accordance with the equation:
x =√{square root over ( x ( f ) 2 )}−√{square root over ( y ( f ) 2 )}
where
X(f)=left channel sub-band frequency component; and
Y(f)=right channel sub-band frequency component.
3 . The system of claim 1 wherein the sub-band vector calculation system generates Y-axis position data Y on the image map in accordance with the equation:
Y
=
x
(
f
)
y
(
f
)
_
x
(
f
)
_
2
y
(
f
)
_
2
where
X(f)=left channel sub-band frequency component; and
Y(f)=right channel sub-band frequency component.
4 . The system of claim 1 wherein the filter stage comprises a left filter receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined left channel gain based on the image map data.
5 . The system of claim 1 wherein the filter stage comprises a left filter receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a left channel gain that decreases linearly from a maximum value at a full-left position to a zero value at a full-right position, based on the image map data.
6 . The system of claim 1 wherein the filter stage comprises a right filter receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined right channel gain that decreases linearly from a maximum value at a full-right position to a zero value at a full-left position, based on the image map data.
7 . The system of claim 1 wherein the filter stage comprises a right filter receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined left channel gain based on the image map data.
8 . The system of claim 1 wherein the filter stage comprises:
a left filter receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined left channel gain based on the image map data; and
a right filter receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined left channel gain based on the image map data.
9 . A method for compensating for signal fade in a frequency-modulated transmission system comprising:
receiving M channels of audio data;
generating a plurality of sub-bands of audio spatial image data from the M channels of audio data;
generating image map data from the M channels of the plurality of sub-bands of audio spatial image data;
adding each of the corresponding sub-bands for each of the M channels to form a plurality of sub-band fine structures; and
multiplying the sub-band fine structures by a predetermined gain based on the image map data.
10 . The method of claim 9 wherein generating image map data comprises generating X-axis position data X in accordance with the equation:
x =√{square root over ( x ( f ) 2 )}−√{square root over ( y ( f ) 2 )}
where
X(f)=left channel sub-band frequency component; and
Y(f)=right channel sub-band frequency component.
11 . The method of claim 9 wherein generating image map data comprises generating Y-axis position data Y on the image map in accordance with the equation:
Y
=
x
(
f
)
y
(
f
)
_
x
(
f
)
_
2
y
(
f
)
_
2
where
X(f)=left channel sub-band frequency component; and
Y(f)=right channel sub-band frequency component.
12 . The method of claim 9 wherein multiplying the sub-band fine structures by the predetermined gain based on the image map data comprises multiplying the sub-band fine structures by a predetermined left channel gain that decreases linearly from a maximum value at a full-left position to a zero value at a full-right position, based on the image map data.
13 . The method of claim 9 wherein multiplying the sub-band fine structures by the predetermined gain based on the image map data comprises multiplying the sub-band fine structures by a predetermined right channel gain that decreases linearly from a maximum value at a full-right position to a zero value at a full-left position, based on the image map data.
14 . A system for compensating for signal fade in a frequency-modulated transmission system comprising:
time domain to frequency domain conversion means for receiving M channels of audio data and generating a plurality of sub-bands of audio spatial image data;
sub-band vector calculation means for receiving the M channels of the plurality of sub-bands of audio spatial image data and generating image map data;
summation stage means for receiving the M channels of the plurality of sub-bands of audio spatial image data and adding each of the corresponding sub-bands for each of the M channels to form a plurality of sub-band fine structures; and
filter stage means for receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined gain based on the image map data.
15 . The system of claim 14 wherein the sub-band vector calculation means generates X-axis position data Δ X on the image map in accordance with the equation:
Δ X =√{square root over ( x ( f ) 2 )}−√{square root over ( y ( f ) 2 )}
where
X(f)=left channel sub-band frequency component; and
Y(f)=right channel sub-band frequency component.
16 . The system of claim 14 wherein the sub-band vector calculation means generates Y-axis position data ψ Y on the image map in accordance with the equation:
Ψ
Y
=
x
(
f
)
y
(
f
)
_
x
(
f
)
_
2
y
(
f
)
_
2
where
X(f)=left channel sub-band frequency component; and
Y(f)=right channel sub-band frequency component.
17 . The system of claim 14 wherein the filter stage means comprises left filter means for receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined left channel gain based on the image map data.
18 . The system of claim 14 wherein the filter stage means comprises right filter means for receiving the plurality of sub-band fine structures and the image map data and multiplying the sub-band fine structures by a predetermined right channel gain that decreases linearly from a maximum value at a full-right position to a zero value at a full-left position, based on the image map data.