Concept for encoding an audio signal and decoding an audio signal using deterministic and noise like information

A method for encoding an audio signal, the method comprising:

• deriving prediction coefficients and a residual signal from an unvoiced frame of the audio signal;
• calculating a first gain parameter information for defining a first excitation signal related to a deterministic codebook and for calculating a second gain parameter information for defining a second excitation signal related to a noise-like signal for the unvoiced frame;
• and
• forming an output signal based on an information related to a voiced signal frame, the first gain parameter information and the second gain parameter information;
• generating an adaptive excitation signal of an adaptive excitation for the voiced signal frame wherein the adaptive excitation is switched off for the unvoiced frame, and/or
• wherein the encoding provides for an unvoiced coding based on a CELP coding scheme that is modified for handling unvoiced frames such that bits saved by switching off the adaptive excitation are reported to the deterministic codebook to code more pulses for a same bit-rate;
• wherein the method comprises determining the first gain parameter based on:
• g
• c
• =
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• xw
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• c
• ⁢
• w
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• wherein cw(n) is a filtered excitation signal of an innovative codebook and xw(n) is a perceptual target excitation computed in CELP encoder;
• wherein the method comprises determining a quantized noise gain based on quantized value of the first gain parameter and the root square energy ratio between the first excitation and the second excitation:
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• c
• ⁡
• (
• n
• )
• ·
• c
• ⁡
• (
• n
• )
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• n
• ⁡
• (
• n
• )
• ·
• n
• ⁡
• (
• n
• )
• wherein Lsf is the size in samples of a subframe;
• wherein c(n) is the first excitation signal, n(n) is the second excitation signal;
• or
• wherein the method comprises quantizing the first gain parameter to acquire a quantized first gain parameter, and determining the first gain parameter as a based on:
• g
• c
• =
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• x
• ⁢
• w
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• cw
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• wherein gc is the first gain parameter, Lsf is the size of the subframe in samples, cw(n) denotes the first shaped excitation signal, xw(n) denotes a Code Excited Linear Prediction encoding signal,
• wherein the method comprises normalizing the first gain parameter to acquire a normalized first gain parameter based on:
• g
• n
• ⁢
• c
• =
• g
• c
• ·
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• c
• ⁡
• (
• n
• )
• ·
• c
• ⁡
• (
• n
• )
• /
• Lsf
• 1
• ⁢
• 0
• wherein gnc denotes the normalized fist gain parameter and n{circumflex over (r)}g is a measure for an average energy of the unvoiced residual signal over the whole frame, wherein c(n) is the first excitation signal;
• and
• wherein the method comprises quantizing the normalized first gain parameter to acquire the quantized first gain parameter.

A non-transitory digital storage medium having stored thereon a computer program for executing a method for encoding an audio signal, the method comprising:

• deriving prediction coefficients and a residual signal from an unvoiced frame of the audio signal;
• calculating a first gain parameter information for defining a first excitation signal related to a deterministic codebook and for calculating a second gain parameter information for defining a second excitation signal related to a noise-like signal for the unvoiced frame;
• and
• forming an output signal based on an information related to a voiced signal frame, the first gain parameter information and the second gain parameter information,
• generating an adaptive excitation signal of an adaptive excitation for the voiced signal frame wherein the adaptive excitation is switched off for the unvoiced frame, and/or
• wherein the encoding provides for an unvoiced coding based on a CELP coding scheme that is modified for handling unvoiced frames such that bits saved by switching off the adaptive excitation are reported to the deterministic codebook to code more pulses for a same bit-rate;
• wherein the method comprises determining the first gain parameter based on:
• g
• c
• =
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• xw
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• c
• ⁢
• w
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• wherein cw(n) is a filtered excitation signal of an innovative codebook and xw(n) is a perceptual target excitation computed in CELP encoder;
• wherein the method comprises determining a quantized noise gain based on quantized value of the first gain parameter and the root square energy ratio between the first excitation and the second excitation:
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• c
• ⁡
• (
• n
• )
• ·
• c
• ⁡
• (
• n
• )
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• n
• ⁡
• (
• n
• )
• ·
• n
• ⁡
• (
• n
• )
• wherein Lsf is the size in samples of a subframe;
• wherein c(n) is the first excitation signal, n(n) is the second excitation signal;
• or
• wherein the method comprises quantizing the first gain parameter to acquire a quantized first gain parameter, and determining the first gain parameter as a based on:
• g
• c
• =
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• x
• ⁢
• w
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• cw
• ⁡
• (
• n
• )
• ·
• cw
• ⁡
• (
• n
• )
• wherein gc is the first gain parameter, Lsf is the size of the subframe in samples, cw(n) denotes the first shaped excitation signal, xw(n) denotes a Code Excited Linear Prediction encoding signal,
• wherein the method comprises normalizing the first gain parameter to acquire a normalized first gain parameter based on:
• g
• n
• ⁢
• c
• =
• g
• c
• ·
• ∑
• n
• =
• 0
• Lsf
• -
• 1
• c
• ⁡
• (
• n
• )
• ·
• c
• ⁡
• (
• n
• )
• /
• Lsf
• 1
• ⁢
• 0
• wherein gnc denotes the normalized fist gain parameter and n{circumflex over (r)}g is a measure for an average energy of the unvoiced residual signal over the whole frame, wherein c(n) is the first excitation signal;
• and
• wherein the method comprises quantizing the normalized first gain parameter to acquire the quantized first gain parameter
• when running on a computer.