Parametric stereo upmix apparatus, a parametric stereo decoder, a parametric stereo downmix apparatus, a parametric stereo encoder
A parametric stereo upmix method for generating a left signal and a right signal from a mono downmix signal based on spatial parameters includes predicting a difference signal comprising a difference between the left signal and the right signal based on the mono downmix signal scaled with a prediction coefficient. The prediction coefficient is derived from the spatial parameters. The method further includes deriving the left signal and the right signal based on a sum and a difference of the mono downmix signal and said difference signal.
1. A method for generating a left signal and a right signal from a mono downmix signal based on spatial parameters, the method comprising act of:
predicting a difference signal comprising a difference between the left signal and the right signal based on the mono downmix signal scaled with a prediction coefficient, wherein said prediction coefficient is derived from the spatial parameters; and
deriving the left signal and the right signal based on a sum and a difference of the mono downmix signal and said difference signal,
wherein the prediction coefficient is given as a function of the spatial parameters:
α
=
iid
-
1
-
j
·
2
·
sin
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
(
ipd
)
·
icc
·
iid
wherein iid, ipd, and icc are the spatial parameters, iid is an interchannel intensity difference, ipd is an interchannel phase difference, and icc is an interchannel coherence.
2. The method of claim 1 , wherein the prediction coefficient is based on waveform matching the mono downmix signal onto the difference signal.
3. The method of claim 1 , wherein the deriving act her based on a prediction residual signal for the difference signal.
4. The method of claim 1 , further comprising the act enhancing the difference signal by adding a scaled decorrelated mono downmix signal formed by scaling a decorrelated mono downmix signal by a scaling factor.
5. The method of claim 4 , further comprising the act of obtaining the decorrelated mono downmix by filtering the mono downmix signal.
6. The method of claim 4 , further comprising the act of setting the scaling factor applied to the decorrelated mono downmix to compensate for a prediction energy loss.
7. A method for generating a left signal and a right signal from a mono downmix signal based on spatial parameters, the method comprising act of:
predicting a difference signal comprising a difference between the left signal and the right signal based on the mono downmix signal scaled with a prediction coefficient, wherein said prediction coefficient is derived from the spatial parameters; and
deriving the left signal and the right signal based on a sum and a difference of the mono downmix signal and said difference signal,
wherein the scaling factor applied to the decorrelated mono downmix is given as a function of the spatial parameters:
β
=
iid
+
1
-
2
·
cos
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
(
ipd
)
·
icc
·
iid
-
α
2
wherein α is the prediction coefficient, iid is an interchannel intensity difference, ipd is an interchannel phase difference, and icc is an interchannel coherence.
8. A non-transitory computer readable medium comprising computer instructions which, when executed by a processor, configure the processor to perform a method for generating a left signal and a right signal from a mono downmix signal based on spatial parameters, the method comprising the acts of:
predicting a difference signal comprising a difference between the left signal and the right signal based on the mono downmix signal scaled with a prediction coefficient, wherein said prediction coefficient is derived from the spatial parameters; and
deriving the left signal and the right signal based on a sum and a difference of the mono downmix signal and said difference signal,
wherein the prediction coefficient is given as a function of the spatial parameters:
α
=
iid
-
1
-
j
·
2
·
sin
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
(
ipd
)
·
icc
·
iid
wherein iid, ipd, and icc are the spatial parameters, iid is an interchannel intensity difference, ipd is an interchannel phase difference, and icc is an interchannel coherence.
9. A non-transitory computer readable medium comprising computer instructions which, when executed b a processor, configure the processor to perform a method for generating a left signal and a right signal from a mono downmix signal based on spatial parameters, the method comprising the acts of:
predicting a difference signal comprising a difference between the left signal and the right signal based on the mono downmix signal scaled with a prediction coefficient, wherein said prediction coefficient is derived from the spatial parameters; and
deriving the left signal and the right signal based on a sum and a difference of the mono downmix signal and said difference signal,
wherein the method further comprises the acts of enhancing the difference signal by adding a scaled decorrelated mono downmix signal formed by scaling a decorrelated mono downmix signal by a scaling factor, wherein the scaling factor applied to the decorrelated mono downmix is given as a function of the spatial parameters:
β
=
iid
+
1
-
2
·
cos
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
(
ipd
)
·
icc
·
iid
-
α
2
wherein α is the prediction coefficient, iid is an interchannel intensity difference, ipd is an interchannel phase difference, and icc is an interchannel coherence.
10. A parametric stereo downmix apparatus for generating a mono downmix signal from a left signal and a right signal based on spatial parameters, wherein said parametric stereo downmix apparatus has a prediction residual signal for a difference signal as an additional output, said parametric stereo downmix apparatus comprising:
a circuit configured to receive the left signal and the right signal and derive the mono downmix signal and a difference signal from the left signal and the right signal, the difference signal comprising a difference between the left signal and the right signal; and
a predictor configured to derive a prediction residual signal for the difference signal as a difference between the difference signal and the mono downmix signal scaled with a predetermined prediction coefficient derived from the spatial parameters,
wherein the prediction coefficient is given as a function of the spatial parameters:
α
=
iid
-
1
-
j
·
2
·
sin
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
(
ipd
)
·
icc
·
iid
wherein iid, ipd, and icc are the spatial parameters, iid is an interchannel intensity difference, ipd is an interchannel phase difference, and icc is an interchannel coherence.
11. A method for generating a prediction residual signal for a difference signal from a left signal and a right signal based on spatial parameters, the method comprising the acts of:
deriving the difference signal between the left signal and the right signal; and
deriving a prediction residual signal for the difference signal as a difference between the difference signal and the mono downmix signal scaled with a prediction coefficient derived from the spatial parameters,
wherein the prediction coefficient is given as a function of the spatial parameters:
α
=
i
i
d
-
1
-
j
·
2
·
sin
(
i
p
d
)
·
i
c
c
·
i
i
d
i
i
d
+
1
+
2
·
cos
(
i
p
d
)
·
i
c
c
·
i
d
d
wherein iid, ipd, and icc are the spatial parameters, iid is an interchannel intensity difference, ipd is an interchannel phase difference, and icc is an interchannel coherence.