Comfort noise addition for modeling background noise at low bit-rates
First Claim
1. A decoder being configured for processing an encoded audio bitstream, wherein the decoder comprises:
- a bitstream decoder configured to derive a decoded audio signal from the bitstream, wherein the decoded audio signal comprises at least one decoded frame;
a noise estimation device configured to produce a noise estimation signal comprising an estimation of the level and/or the spectral shape of a noise in the decoded audio signal;
a comfort noise generating device configured to derive a comfort noise signal from the noise estimation signal, wherein the comfort noise generating device is configured to create the comfort noise signal based on a target comfort noise level signal; and
a combiner configured to combine the decoded frame of the decoded audio signal and the comfort noise signal in order to acquire an audio output signal, in such way that the decoded frame in the audio output signal comprises artificial noise.
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Abstract
The invention provides a decoder being configured for processing an encoded audio bitstream, wherein the decoder includes: a bitstream decoder configured to derive a decoded audio signal from the bitstream, wherein the decoded audio signal includes at least one decoded frame; a noise estimation device configured to produce a noise estimation signal containing an estimation of the level and/or the spectral shape of a noise in the decoded audio signal; a comfort noise generating device configured to derive a comfort noise signal from the noise estimation signal; and a combiner configured to combine the decoded frame of the decoded audio signal and the comfort noise signal in order to obtain an audio output signal.
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Citations
25 Claims
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1. A decoder being configured for processing an encoded audio bitstream, wherein the decoder comprises:
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a bitstream decoder configured to derive a decoded audio signal from the bitstream, wherein the decoded audio signal comprises at least one decoded frame; a noise estimation device configured to produce a noise estimation signal comprising an estimation of the level and/or the spectral shape of a noise in the decoded audio signal; a comfort noise generating device configured to derive a comfort noise signal from the noise estimation signal, wherein the comfort noise generating device is configured to create the comfort noise signal based on a target comfort noise level signal; and a combiner configured to combine the decoded frame of the decoded audio signal and the comfort noise signal in order to acquire an audio output signal, in such way that the decoded frame in the audio output signal comprises artificial noise. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21)
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20. An encoder being configured for producing an audio bitstream, wherein the encoder comprises:
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a bitstream encoder configured to produce an encoded audio signal corresponding to an audio input signal and to derive the bitstream from the encoded audio signal; a signal analyzer comprising a signal-to-noise ratio estimator configured to determine the signal-to-noise ratio of the audio input signal based on an energy of a wanted signal of the audio input signal determined by a wanted signal energy estimator and based on an energy of a noise of the audio input signal determined by noise energy estimator; a comparison device configured to compare the determined sign-to-noise ratio with a threshold; a noise reduction device configured to produce a noise reduced audio signal; and a switch device configured to feed, depending on the result of the comparison of signal-to-noise ratio of the audio input signal, either the audio input signal or the noise reduced audio signal to the bitstream encoder for encoding the respective signal, wherein the bitstream encoder is configured to transmit a side information, which indicates whether the audio input signal or the noise reduced audio signal is encoded, within in the bitstream.
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22. A method of decoding an audio bitstream, wherein the method comprises:
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deriving a decoded audio signal from the bitstream, wherein the decoded audio signal comprises at least one decoded frame; producing a noise estimation signal comprising an estimation of the level and/or the spectral shape of a noise in the decoded audio signal; deriving a comfort noise signal from the noise estimation signal and based on a target comfort noise level signal; and combining the decoded frame of the decoded audio signal and the comfort noise signal in order to acquire an audio output signal, in such way that the decoded frame in the audio output signal comprises artificial noise. - View Dependent Claims (24)
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23. A method of audio signal encoding for producing an audio bitstream, wherein the method comprises:
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determining a signal-to-noise ratio of an audio input signal based on a determined energy of a wanted signal of the audio input signal and a determined energy of a noise of the audio input signal; comparing the determined signal-to-noise ratio with a threshold; producing a noise reduced audio signal; producing an encoded audio signal corresponding to the audio input signal, wherein, depending on the result of the comparison of the signal-to-noise ratio of the audio input signal, either the audio input signal or the noise reduced audio signal is encoded; deriving the bitstream from the encoded audio signal; and transmitting a side information, which indicates whether the audio input signal or the noise reduced audio signal is encoded, within the bitstream. - View Dependent Claims (25)
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Specification