Energy envelope perceptual correction for high band coding
First Claim
1. A method of encoding an audio bitstream at an encoder, the method comprising:
- encoding an original low band signal at the encoder by using a closed loop analysis-by-synthesis approach to obtain a coded low band signal;
encoding an original high band signal at the encoder by using an open loop energy matching approach to obtain coded high band energy envelopes;
comparing an energy of the coded low band signal with an energy of a corresponding original low band signal for a subframe;
generating an indication flag that indicates whether an energy envelope perceptual correction is needed for the subframe based on comparing the energy; and
electronically transmitting the coded low band signal, the coded high band energy envelopes, and the indication flag.
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Abstract
In accordance with an embodiment, A method of encoding an audio bitstream at an encoder includes encoding an original low band signal at the encoder by using a closed loop analysis-by-synthesis approach to obtain a coded low band signal, encoding an original high band signal at the encoder by using an open loop energy matching approach to obtain coded high band energy envelopes, comparing an energy of the coded low band signal with an energy of a corresponding original low band signal for a subframe, and generating an indication flag that indicates whether an energy envelope perceptual correction is needed for the subframe based on comparing the energy.
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Citations
34 Claims
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1. A method of encoding an audio bitstream at an encoder, the method comprising:
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encoding an original low band signal at the encoder by using a closed loop analysis-by-synthesis approach to obtain a coded low band signal; encoding an original high band signal at the encoder by using an open loop energy matching approach to obtain coded high band energy envelopes; comparing an energy of the coded low band signal with an energy of a corresponding original low band signal for a subframe; generating an indication flag that indicates whether an energy envelope perceptual correction is needed for the subframe based on comparing the energy; and electronically transmitting the coded low band signal, the coded high band energy envelopes, and the indication flag. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of decoding an encoded audio bitstream at a decoder, the method comprising:
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electronically receiving the encoded audio bitstream, the encoded audio bitstream comprising a coded low band signal, coded high band energy envelopes, and an indication flag; performing an energy envelope perceptual correction by reducing amplitudes of the coded high band energy envelopes if the indication flag is in a true state; generating a high band signal by applying the coded high band energy envelopes after performing the energy envelope perceptual correction; and forming an output speech/audio signal from the coded low band signal and the generated high band signal. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of encoding an audio bitstream at an encoder, the method comprising:
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encoding an original low band signal at the encoder by using a closed loop analysis-by-synthesis approach to obtain a coded low band signal; encoding an original high band signal at the encoder by using an open loop energy matching approach to obtain coded high band energy envelopes; comparing an energy of the coded low band signal with an energy of a corresponding original low band signal; generating an indication flag that indicates whether an energy envelope perceptual correction is needed based on comparing the energy; calculating high band energy envelopes of the original high band signal at the encoder; applying energy envelope perceptual correction by reducing amplitudes of the high band energy envelopes if the indication flag is true; encoding the high band energy envelopes after applying the energy envelope perceptual correction at the encoder by using an open loop energy matching to obtain coded high band energy envelopes; and electronically transmitting the coded low band signal, and the coded high band energy envelopes. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A system for encoding an audio signal, the system comprising:
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a low band encoder configured to encode an original low band signal using a closed loop analysis-by-synthesis approach to obtain a coded low band signal; a high band encoder configured to encode an original high band signal using an open loop energy matching approach to obtain coded high band energy envelopes; an energy comparison block configured to compare an energy of the coded low band signal with an energy of a corresponding original low band signal for a subframe, and generate an indication flag to indicate whether an energy envelope perceptual correction is needed for the subframe based on comparing the energy; and an interface block configured to transmit the coded low band signal, the coded high band energy envelopes, and the indication flag. - View Dependent Claims (23, 24, 25)
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26. A system for encoding an audio signal, the system comprising:
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a low band encoder configured to encode an original low band signal using a closed loop analysis-by-synthesis approach to obtain a coded low band signal; a high band encoder configured to encode an original high band signal using an open loop energy matching approach to obtain coded high band energy envelopes; an energy comparison block configured to compare an energy of the coded low band signal with an energy of a corresponding original low band signal for a subframe, and generate an indication flag that indicates whether an energy envelope perceptual correction is needed for the subframe based on comparing the energy; a correction block configured to reduce amplitudes of the high band energy envelopes if the indication flag is true; a high band energy envelope encoder configured to encode the high band energy envelopes after applying the energy envelope perceptual correction at the encoder by using an open loop energy matching to obtain coded high band energy envelopes; and an interface block configured to transmit the coded low band signal, and the coded high band energy envelopes. - View Dependent Claims (27, 28, 29)
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30. A system for decoding an encoded audio bitstream, the system comprising:
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a receiver for receiving an encoded bitstream comprising a coded low band signal, coded high band energy envelopes, and an indication flag; a perceptual correction block configured to reduce amplitudes of the coded high band energy envelopes to form corrected coded high band energy envelopes if the indication flag is in a true state; a high band signal generator coupled to the perceptual correction block, the high band signal generator configured to apply the high band energy envelopes to form a generated high band signal; and a filter bank synthesis block configured to form an output speech/audio signal from the coded low band signal and the generated high band signal. - View Dependent Claims (31, 32)
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33. A non-transitory computer readable medium has an executable program stored thereon, wherein the program instructs a processor to perform the steps of:
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encoding an original low band signal using a closed loop analysis-by-synthesis approach to obtain a coded low band signal; encoding an original high band signal using an open loop energy matching approach to obtain coded high band energy envelopes; comparing an energy of the coded low band signal with an energy of a corresponding original low band signal for a subframe; generating an indication flag that indicates whether an energy envelope perceptual correction is needed for the subframe based on comparing the energy; and transmitting the coded low band signal, the coded high band energy envelopes, and the indication flag.
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34. A non-transitory computer readable medium has an executable program stored thereon, wherein the program instructs a processor to perform the steps of:
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encoding an original low band signal using a closed loop analysis-by-synthesis approach to obtain a coded low band signal; encoding an original high band signal using an open loop energy matching approach to obtain coded high band energy envelopes; comparing an energy of the coded low band signal with an energy of a corresponding original low band signal for a subframe; generating an indication flag that indicates whether an energy envelope perceptual correction is needed for the subframe based on comparing the energy; calculating high band energy envelopes of the original high band signal at the encoder; applying energy envelope perceptual correction by reducing amplitudes of the high band energy envelopes if the indication flag is true; encoding the high band energy envelopes after applying the energy envelope perceptual correction at the encoder by using an open loop energy matching to obtain coded high band energy envelopes; and transmitting the coded low band signal, and the coded high band energy envelopes.
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Specification