Advanced stereo coding based on a combination of adaptively selectable left/right or mid/side stereo coding and of parametric stereo coding
First Claim
1. An encoder system encoding a stereo signal to a bitstream signal, the encoder system comprising:
- a downmix stage generating a downmix signal and a residual signal based on the stereo signal;
a parameter determining stage coupled to the downmix stage and determining one or more parametric stereo parameters;
a perceptual encoder coupled downstream to the downmix stage, wherein the perceptual encoder selectsencoding based on a sum of the downmix signal and the residual signal and based on a difference of the downmix signal and the residual signal, orencoding based on the downmix signal and based on the residual signal in a frequency-variant or frequency-invariant manner.
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Abstract
The application relates to audio encoder and decoder systems. An embodiment of the encoder system comprises a downmix stage for generating a downmix signal and a residual signal based on a stereo signal. In addition, the encoder system comprises a parameter determining stage for determining parametric stereo parameters such as an inter-channel intensity difference and an inter-channel cross-correlation. Preferably, the parametric stereo parameters are time- and frequency-variant. Moreover, the encoder system comprises a transform stage. The transform stage generates a pseudo left/right stereo signal by performing a transform based on the downmix signal and the residual signal. The pseudo stereo signal is processed by a perceptual stereo encoder. For stereo encoding, left/right encoding or mid/side encoding is selectable. Preferably, the selection between left/right stereo encoding and mid/side stereo encoding is time- and frequency-variant.
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Citations
20 Claims
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1. An encoder system encoding a stereo signal to a bitstream signal, the encoder system comprising:
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a downmix stage generating a downmix signal and a residual signal based on the stereo signal; a parameter determining stage coupled to the downmix stage and determining one or more parametric stereo parameters; a perceptual encoder coupled downstream to the downmix stage, wherein the perceptual encoder selects encoding based on a sum of the downmix signal and the residual signal and based on a difference of the downmix signal and the residual signal, or encoding based on the downmix signal and based on the residual signal in a frequency-variant or frequency-invariant manner. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An encoder system encoding a stereo signal to a bitstream signal, the encoder system comprising:
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a downmix stage generating a downmix signal and a residual signal based on the stereo signal; a parameter determining stage coupled to the downmix stage, and determining one or more parametric stereo parameters; a transform stage coupled to the downmix stage, and performing a transform based on the downmix signal and the residual signal, thereby generating a pseudo left/right stereo signal; and a perceptual stereo encoder coupled to the downmix stage and encoding the pseudo left/right stereo signal, wherein the perceptual stereo encoder is configured to select left/right perceptual encoding or mid/side perceptual encoding in a frequency-variant or frequency-invariant manner.
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9. A decoder system decoding a bitstream signal including one or more parametric stereo parameters to a stereo signal, the decoder system comprising:
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a perceptual decoder decoding based on the bitstream signal, wherein the perceptual decoder generating by decoding a first signal and a second signal and outputting a downmix signal and a residual signal, wherein the perceptual decoder selects the downmix signal and the residual signal based on a sum of the first signal and of the second signal and based on a difference of the first signal and of the second signal or based on the first signal and based on the second signal in a frequency-variant or frequency-invariant manner; and an upmixer coupled to the perceptual decoder, and generating the stereo signal based on the downmix signal and the residual signal, with the upmix operation of the upmixer being dependent on the one or more parametric stereo parameters. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A decoder system decoding a bitstream signal including one or more parametric stereo parameters to a stereo signal, the decoder system comprising:
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a perceptual stereo decoder decoding based on the bitstream signal, the decoder generating a pseudo stereo signal, wherein the decoder selectively performs left/right perceptual decoding or mid/side perceptual decoding in a frequency-variant or frequency-invariant manner; a left/right to mid/side transformation stage performing a left/right to mid/side transform based on the pseudo stereo signal, thereby generating a downmix signal and a residual signal; and an upmixer coupled to the perceptual stereo decoder, and generating the stereo signal based on the downmix signal and the residual signal, with the upmix operation of the upmixer being dependent on the one or more parametric stereo parameters.
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17. A method for encoding a stereo signal to a bitstream signal, the method comprising:
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generating a downmix signal and a residual signal based on the stereo signal; determining one or more parametric stereo parameters; perceptual encoding downstream of generating the downmix signal and the residual signal, wherein encoding based on a sum of the downmix signal and the residual signal and based on a difference of the downmix signal and the residual signal or encoding based on the downmix signal and based on the residual signal is selectable in a frequency-variant or frequency-invariant manner; wherein the method is performed by one or more microprocessor-based components.
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18. A method for encoding a stereo signal to a bitstream signal, the method comprising:
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generating a downmix signal and a residual signal based on the stereo signal; determining one or more parametric stereo parameters; generating a pseudo left/right stereo signal by performing a transform based on the downmix signal and the residual signal; and performing perceptual stereo encoding of the pseudo left/right stereo signal, wherein left/right perceptual encoding or mid/side perceptual encoding is selectable in a frequency-variant or frequency-invariant manner; wherein the method is performed by one or more microprocessor-based components.
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19. A method for decoding a bitstream signal including one or more parametric stereo parameters to a stereo signal, the method comprising:
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perceptual decoding based on the bitstream signal, wherein a first signal and a second signal is generated by decoding and a downmix signal and a residual signal is output after perceptual decoding, the downmix signal and the residual signal being selectively based on the sum of the first signal and of the second signal and based on the difference of the first signal and of the second signal or based on the first signal and based on the second signal in a frequency-variant or frequency-invariant manner; and generating the stereo signal based on the downmix signal and the residual signal by an upmix operation, with the upmix operation being dependent on the one or more parametric stereo parameters; wherein the method is performed by one or more microprocessor-based components.
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20. A method for decoding a bitstream signal including one or more parametric stereo parameters to a stereo signal, the method comprising:
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performing perceptual stereo decoding based on the bitstream signal to generate a pseudo stereo signal, wherein left/right perceptual decoding or mid/side perceptual decoding is selectable in a frequency-variant or frequency-invariant manner; generating a downmix signal and a residual signal by performing a transform based on the pseudo stereo signal; and generating the stereo signal based on the downmix signal and the residual signal by an upmix operation, with the upmix operation being dependent on the one or more parametric stereo parameters; wherein the method is performed by one or more microprocessor-based components.
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Specification