Coding of audio signals
First Claim
1. An encoder comprising an input for inputting frames of an audio signal in a frequency band, a filter for dividing the frequency band into at least a lower frequency band and a higher frequency band, a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block for encoding the audio signals of the higher frequency band, a mode selector for selecting an operating mode for the encoder among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, and a scaler to control the second encoding block to gradually change the encoding properties of the second encoding block in connection with a change in the operating mode of the encoder.
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Accused Products
Abstract
An encoder comprises an input for inputting frames of an audio signal in a frequency band, an analysis filter dividing the frequency band into lower and higher frequency bands, a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block for encoding the audio signals of the higher frequency band, and a mode selector for selecting an operating mode for the encoder among at least a first mode where signals only on the lower frequency band are encoded, and a second mode where signals on both the lower and higher frequency band are encoded. The encoder has a scaler to gradually change the encoding properties of the second encoding block in connection with a change in the operating mode of the encoder. The invention also relates to a device, a decoder, a method, a module, a computer program product, and a signal.
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Citations
30 Claims
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1. An encoder comprising
an input for inputting frames of an audio signal in a frequency band, a filter for dividing the frequency band into at least a lower frequency band and a higher frequency band, a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block for encoding the audio signals of the higher frequency band, a mode selector for selecting an operating mode for the encoder among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, and a scaler to control the second encoding block to gradually change the encoding properties of the second encoding block in connection with a change in the operating mode of the encoder.
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11. An AMR-WB encoder comprising
an input for inputting frames of an audio signal in a frequency band, a filter for dividing the frequency band into at least a lower frequency band and a higher frequency band, a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block (for encoding the audio signals of the higher frequency band, a mode selector for selecting an operating mode for the encoder among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, and a scaler to control the second encoding block to gradually change the encoding properties of the second encoding block in connection with a change in the operating mode of the encoder.
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13. A device comprising an encoder comprising
an input for inputting frames of an audio signal in a frequency band, an analysis filter for dividing the frequency band into at least a lower frequency band and a higher frequency band, a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block for encoding the audio signals of the higher frequency band, and a mode selector for selecting an operating mode for the encoder among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, wherein the encoder further comprises a scaler to control the second encoding block to gradually change the encoding properties of the encoding block in connection with a change in the operating mode of the encoder.
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15. A system comprising an encoder comprising
an input for inputting frames of an audio signal in a frequency band, a filter for dividing the frequency band into at least a lower frequency band and a higher frequency band, a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block for encoding the audio signals of the higher frequency band, and a mode selector for selecting an operating mode for the encoder among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, wherein the system further comprises a scaler to control the second encoding block to gradually change the encoding properties of the second encoding block in connection with a change in the operating mode of the encoder.
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17. A method for compressing audio signals in a frequency band, the method comprising
dividing the frequency band into at least a lower frequency band and a higher frequency band, encoding the audio signals of the lower frequency band by a first encoding block, encoding the audio signals of the higher frequency band by a second encoding block, selecting an operating mode for the encoding among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, and gradually changing encoding properties of the second encoding block in connection with a change in the operating mode.
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25. A module for encoding frames of an audio signal in a frequency band which is divided into at least a lower frequency band and a higher frequency band, the module comprising
a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block for encoding the audio signals of the higher frequency band, a mode selector for selecting an operating mode for the module among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, and a scaler to control the second encoding block to gradually change the encoding properties of the second encoding block in connection with a change in the operating mode of the module.
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27. A computer program product comprising machine executable steps stored in a readable medium for execution on a processor, the machine executable steps when executed for
compressing audio signals in a frequency band divided into at least a lower frequency band and a higher frequency band, encoding the audio signals of the lower frequency band by a first encoding block, encoding the audio signals of the higher frequency band by a second encoding block, selecting an operating mode for the encoding among at least a first mode and a second mode, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, and gradually changing the encoding properties of the second encoding block in connection with a change in the operating mode.
- 29. A signal comprising a bit stream including parameters for a decoder to decode said bit stream, the bit stream being encoded from frames of an audio signal in a frequency band, which is divided into at least a lower frequency band and a higher frequency band, and at least a first mode and a second mode are defined for the signal, in which first mode signals only on the lower frequency band are encoded, and in which second mode signals on both the lower and higher frequency band are encoded, wherein on a mode change between said first mode and said second mode at least one of the parameters of the signal relating to said higher frequency band are gradually changed.
Specification