# US 12,192,734 B2 · Parametric stereo upmix apparatus, a parametric stereo decoder, a parametric stereo downmix apparatus, a parametric stereo encoder

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,192,734 B2
- Document ID: US12192734B2
- Status: Granted
- Kind: B2
- Application number: 18/525,910
- Filed: 2023-12-01
- Published: 2024-04-11
- Granted: 2025-01-07
- Earliest claimed: 2008-05-23
- Assignees: Koninklijke Philips N.V.
- Applicants: Koninklijke Philips N.V.
- Inventors: Erik G. P. Schuijers
- Web page: https://patentgrep.com/patent/US12192734B2

## CPC

- H04S 5/00: Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation
- G10L 19/008: Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
- H04S 3/02: of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other
- H04S 2400/03: Aspects of down-mixing multi-channel audio to configurations with lower numbers of playback channels, e.g. 7.1 -> 5.1 (H04S2400/01 takes precedence)
- H04S 2420/03: Application of parametric coding in stereophonic audio systems
- H04S: STEREOPHONIC SYSTEMS
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING

## Abstract

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.

## Claims

### Claim 1

A method, comprising:
splitting an input bitstream into a mono bitstream and a parameter bitstream;
decoding the mono bitstream into a mono downmix signal;
decoding the parameter bitstream into spatial parameters;
scaling the mono downmix signal with a prediction coefficient (α) to produce a scaled mono downmix signal;
predicting a first difference signal, wherein the predicting is based on the scaled mono downmix signal;
adding a scaled decorrelated mono downmix signal to the first difference signal to form a second difference signal, wherein the scaled decorrelated mono downmix signal is formed by scaling a decorrelated mono downmix signal by a scaling factor (β);
forming the left signal based on a sum of the mono downmix signal and the second difference signal; and
forming the right signal based on a difference between the mono downmix signal and the second difference signal wherein the scaling factor (β) is:
β
=
iid
+
1
-
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
-
❘
"\[LeftBracketingBar]"
α
❘
"\[RightBracketingBar]"
2
wherein iid, ipd, and icc are the spatial parameters,
wherein iid is an interchannel intensity difference,
wherein ipd is an interchannel phase difference, and
wherein icc is an interchannel coherence.

### Claim 2 (depends on 1)

The method of claim 1, wherein the prediction coefficient (α) is:
α
=
iid
-
1
-
j
·
2
·
sin
⁡
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
.

### Claim 3 (depends on 1)

The method of claim 1 wherein the scaling factor (β) is derived from spatial parameters.

### Claim 4 (depends on 1)

The method of claim 1, wherein the prediction residual signal has substantially zero correlation with the mono downmix signal.

### Claim 5 (depends on 1)

The method of claim 1 wherein the scaling factor (β) compensates for a prediction energy loss.

### Claim 6 (depends on 1)

The method of claim 1, wherein the prediction coefficient (α) is based on waveform matching the downmix signal onto the first difference signal.

### Claim 7 (depends on 1)

A computer program stored on a non-transitory medium, wherein the computer program when executed on a processor performs the method as claimed in claim 1.

### Claim 8

A method, comprising:
splitting an input bitstream into a mono bitstream and a parameter bitstream;
extracting a prediction residual bitstream from the input bitstream;
decoding the mono bitstream into a mono downmix signal;
decoding a prediction residual signal from the prediction residual bitstream;
decoding the parameter bitstream into spatial parameters;
scaling the mono downmix signal with a prediction coefficient (α) to produce a scaled mono downmix signal;
predicting a first difference signal, wherein the predicting is based on the scaled mono downmix signal;
adding a scaled decorrelated mono downmix signal to the first difference signal to form a second difference signal, wherein the scaled decorrelated mono downmix signal is formed by scaling a decorrelated mono downmix signal by a scaling factor (β);
forming a first portion of the left signal based on a sum of the mono downmix signal, the first difference signal, and the prediction residual signal;
forming a second portion of the left signal based on a sum of the mono downmix signal and the second difference signal;
forming a first portion of the right signal based on a difference between the mono downmix signal, and a sum of the first difference signal and the prediction residual signal; and
forming a second portion of the right signal based on a difference between the mono downmix signal and the second difference signal
wherein the scaling factor (β) is:
β
=
iid
+
1
-
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
-
❘
"\[LeftBracketingBar]"
α
❘
"\[RightBracketingBar]"
2
wherein iid, ipd, and icc are the spatial parameters,
wherein iid is an interchannel intensity difference,
wherein ipd is an interchannel phase difference, and
wherein icc is an interchannel coherence.

### Claim 9 (depends on 8)

The method of claim 8,
wherein the first portion is a first frequency subband,
wherein the second portion is a second frequency subband,
wherein the first frequency subband is different from the second frequency subband.

### Claim 10 (depends on 8)

The method of claim 8,
wherein the first portion comprises a first frequency subband,
wherein the second portion comprises a second frequency subband,
wherein the first frequency subband does not overlap the second frequency subband.

### Claim 11 (depends on 8)

The method of claim 8, wherein the prediction coefficient (α) is:
α
=
iid
-
1
-
j
·
2
·
sin
⁡
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
.

### Claim 12 (depends on 8)

The method of claim 8 wherein the scaling factor (β) is derived from spatial parameters.

### Claim 13 (depends on 8)

The method of claim 8, wherein the prediction residual signal has substantially zero correlation with the mono downmix signal.

### Claim 14 (depends on 8)

The method of claim 8 wherein the scaling factor (β) compensates for a prediction energy loss.

### Claim 15 (depends on 8)

The method of claim 8, wherein the prediction coefficient (α) is based on waveform matching the downmix signal onto the first difference signal.

### Claim 16 (depends on 8)

A computer program stored on a non-transitory medium, wherein the computer program when executed on a processor performs the method as claimed in claim 8.

### Claim 17

A method, comprising:
splitting an input bitstream into a mono bitstream and a parameter bitstream, wherein the input bitstream comprises a plurality of subbands;
extracting a prediction residual bitstream from the input bitstream, wherein the prediction residual bitstream comprises a third portion of plurality of subbands;
decoding the mono bitstream into a mono downmix signal,
wherein the mono downmix signal comprises mono downmix subband signals,
wherein the mono downmix subband signal comprises a fourth portion of the plurality of subbands;
decoding a prediction residual signal,
wherein the prediction residual signal comprises prediction residual subband signals,
wherein the prediction residual subband signals comprise a fifth portion of the third portion of the plurality of subbands;
decoding the parameter bitstream into spatial parameters for at least one subband of the plurality of subbands;
scaling the mono downmix subband signal with a prediction coefficient (α) to produce a scaled mono downmix subband signal for at least one subband of the plurality of subbands;
predicting a first difference subband signal for at least one subband of the plurality of subbands, wherein the predicting is based on the scaled mono downmix subband signal;
adding a scaled decorrelated mono downmix subband signal to the first difference subband signal for at least one subband of the plurality of subbands to form a second difference subband signal, wherein the scaled decorrelated mono downmix subband signal is formed by scaling a decorrelated mono downmix subband signal by a scaling factor (β);
forming a first portion of the left signal,
wherein the first portion of the left signal comprises one or more subbands,
wherein each subband is based on a sum of the mono downmix subband signal, the first difference subband signal, and the prediction residual subband signal;
forming a second portion of the left signal,
wherein the second portion of the left signal comprises one or more subbands,
wherein each subband is based on a sum of the mono downmix subband signal and the second difference subband signal;
forming a first portion of the right signal,
wherein the first portion of the right signal comprises one or more subbands,
wherein each subband is based on a difference between the mono downmix subband signal, and a sum of the first difference subband signal and the prediction residual subband signal; and
forming a second portion of the right signal,
wherein the second portion of the right signal comprises one or more subbands,
wherein each subband is based on a difference between the mono downmix subband signal and the second difference subband signal
wherein the scaling factor (β) is:
β
=
iid
+
1
-
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
-
❘
"\[LeftBracketingBar]"
α
❘
"\[RightBracketingBar]"
2
wherein iid, ipd, and icc are the spatial parameters,
wherein iid is an interchannel intensity difference,
wherein ipd is an interchannel phase difference, and
wherein icc is an interchannel coherence.

### Claim 18 (depends on 17)

The method of claim 17, wherein the prediction coefficient (α) is:
α
=
iid
-
1
-
j
·
2
·
sin
⁡
(
ipd
)
·
icc
·
iid
iid
+
1
+
2
·
cos
⁡
(
ipd
)
·
icc
·
iid
.

### Claim 19 (depends on 17)

The method of claim 17 wherein the scaling factor (β) is derived from spatial parameters.

### Claim 20 (depends on 17)

The method of claim 17, wherein the prediction residual signal has substantially zero correlation with the mono downmix signal.

### Claim 21 (depends on 17)

The method of claim 17 wherein the scaling factor (β) compensates for a prediction energy loss.

### Claim 22 (depends on 17)

The method of claim 17, wherein the prediction coefficient (α) is based on waveform matching the downmix signal onto the first difference signal.

### Claim 23 (depends on 17)

A computer program stored on a non-transitory medium, wherein the computer program when executed on a processor performs the method as claimed in claim 17.