Method and apparatus to encode/decode low bit-rate audio signal by approximiating high frequency envelope with strongly correlated low frequency codevectors
First Claim
1. A method of encoding a low bit-rate audio signal, the method comprising:
- quantizing and encoding a plurality of first frequency sub-bands in a low frequency region of a full-band audio signal having a plurality of frequency sub-bands;
generating a codebook of codevectors using one or more of the plurality of overlapping first frequency sub-bands of the low frequency region of the full-band audio signal to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution;
detecting an envelope of at least one second frequency sub-band in a high frequency region of the full-band audio signal higher than the highest low frequency sub-band and quantizing and encoding the envelope;
selecting a codevector in the first frequency sub-band codebook that is most similar to the second frequency sub-band to be encoded from the generated codebook'"'"'s codevectors and determining a codebook codevector index which defines a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band; and
generating a bit stream using encoded data generated in the encoding of the first frequency sub-band, the envelope, and the determined codebook codevector index.
1 Assignment
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Accused Products
Abstract
A method of encoding a low bit-rate audio signal includes quantizing and encoding a plurality of low frequency sub-bands of an audio signal in a frequency domain, generating a codebook of codevectors using sub-bands of the audio signal spectrum, detecting an envelope of another frequency sub-band of the audio signal and quantizing and losslessly-encoding the detected envelope, selecting a codevector most similar to the higher frequency sub-band spectrum from the generated codebook'"'"'s codevectors and determining its codebook codevector index, and generating a bit stream. Decoding the low bit-rate audio signal includes restoring and dividing a bit stream into a plurality of first frequency sub-bands and at least one second frequency sub-band and inversely quantizing the first frequency sub-bands in the bit stream, restoring codebook codevector index information and envelope information for the second frequency sub-band, generating a codebook of codevectors using the inversely quantized first frequency sub-bands, and restoring the second frequency sub-band using the restored codevector index information and the envelope information.
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Citations
44 Claims
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1. A method of encoding a low bit-rate audio signal, the method comprising:
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quantizing and encoding a plurality of first frequency sub-bands in a low frequency region of a full-band audio signal having a plurality of frequency sub-bands; generating a codebook of codevectors using one or more of the plurality of overlapping first frequency sub-bands of the low frequency region of the full-band audio signal to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution; detecting an envelope of at least one second frequency sub-band in a high frequency region of the full-band audio signal higher than the highest low frequency sub-band and quantizing and encoding the envelope; selecting a codevector in the first frequency sub-band codebook that is most similar to the second frequency sub-band to be encoded from the generated codebook'"'"'s codevectors and determining a codebook codevector index which defines a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band; and generating a bit stream using encoded data generated in the encoding of the first frequency sub-band, the envelope, and the determined codebook codevector index. - View Dependent Claims (2)
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3. A method of encoding a low bit-rate audio signal, the method comprising:
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quantizing and encoding a plurality of first frequency sub-bands in a low frequency region of a full-band audio signal having a plurality of frequency sub-bands; generating a codebook of codevectors using one or more of the plurality of first frequency sub-bands of the low frequency region of the full band audio signal to vector quantize at least one high-frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution; detecting an envelope of a second frequency sub-band in the high frequency region of the full-band audio signal higher than the highest low frequency sub-band and quantizing and encoding the detected envelope of the second frequency sub-band; checking whether a codevector having at least a predetermined similarity exists among the generated codevectors of the codebook with respect to a high frequency band to be encoded; if the similar codevector exists, selecting the similar codevector, determining a codebook codevector index which defines a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band; if a similar codevector does not exist, encoding information indicating that a similar codevector does not exist; and generating a bit stream using encoded data generated in the encoding of the first frequency sub-band, the envelope of the second frequency sub-band, the determined codebook codevector index, and the information indicating that the similar codebook does not exist. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. An apparatus to encode a low bit-rate audio signal, the apparatus comprising:
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a low frequency quantizing/encoding unit which quantizes and encodes a plurality of first frequency sub-bands in a low frequency region of a full-band audio signal having a plurality of frequency sub-bands; a codebook generating unit which generates a codebook of codevectors using one or more of the plurality of first frequency sub-bands of the low frequency region of the full-band audio signal to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution; an envelope quantizing/encoding unit which detects an envelope of at least one second frequency sub-band in a high frequency region of the full-band audio signal higher than the highest low frequency sub-band and quantizes and encodes the detected envelope of the second frequency sub-band; a codebook index acquiring unit which selects a codevector in the first frequency sub-band codebook most similar to the second frequency sub-band to be encoded from among the generated codebook'"'"'s codevectors and determines a codebook codevector index to define a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band; and a bit stream generating unit which generates a bit stream using encoded data which are generated by the low frequency quantizing/encoding unit, and the envelope quantizing/encoding unit and the determined codebook codevector index. - View Dependent Claims (11)
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12. An apparatus to encode a low bit-rate audio signal, the apparatus comprising:
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a low frequency quantizing/encoding unit which quantizes and encodes a plurality of first frequency sub-bands in a low frequency region of a full-band audio signal having a plurality of frequency sub-bands; a codebook generating unit which generates a codebook of codevectors using one or more of the plurality of first frequency sub-bands of the low frequency region of the full-band audio signal to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution; an envelope quantizing/encoding unit which detects an envelope of at least one second frequency sub-band of a high frequency region of the full-band audio signal higher than the highest low frequency sub-band and quantizes and encodes the detected envelope of the second frequency sub-band; a similarity checking unit which checks whether a codevector of the codebook having at least a predetermined similarity exists among the generated codevectors of the codebook with respect to a high frequency band to be encoded; a codebook existence information/index encoding unit which selects a similar codevector from the codebook, determines a codebook codevector index which defines a fine structure of the first frequency sub-band if the similar codevector in the codebook exists, and encodes the determined codebook codevector index and information indicating that the similar codevector exists; a codebook existence information encoding unit which encodes information indicating that a similar codevector in the codebook does not exist if a similar codevector in the codebook does not exist; and a bitstream generating unit which generates a bit stream using encoded data which are generated by the low frequency quantizing/encoding unit, the codebook existence information/index encoding unit, and the codebook existence information encoding unit. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. An encoding apparatus, comprising:
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a first quantizing/encoding unit to quantize a plurality of first frequency sub-bands of a full spectrum audio signal having a plurality of frequency sub-bands and to encode the quantized first frequency sub-bands; a second quantizing/encoding unit to quantize one or more envelopes of at least one second frequency sub-band of the full spectrum audio signal and to encode the quantized one or more envelopes; a codebook unit to generate a codebook of one or more codevectors from the first frequency sub-bands to vector quantize the at least one second frequency sub-band of the plurality of frequency sub-bands or to encode the at least one second frequency sub-band by perceptual noise substitution, to determine whether a similar codevector in the codebook exists for the second frequency sub-band, and to encode codevector existence information to indicate similarities between the second frequency sub-bands and the codevectors in the codebook; and a bit stream unit to generate a bitstream including the encoded first frequency sub-band, the encoded envelopes of the at least one second frequency sub-band, and the encoded codevector existence information. - View Dependent Claims (20)
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21. A method of decoding a low bit-rate audio signal, the method comprising:
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dividing a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands, and at least one second frequency sub-band other than the first frequency sub-band of the full-band audio signal; decoding and inversely quantizing the first frequency sub-bands of the full-band audio signal; restoring codebook codevector index information which defines a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band and envelope information about the second frequency sub-band; generating a codebook of codevectors using the inversely quantized first frequency sub-band to inversely vector quantize the at least one second frequency sub-band or to decode the at least one second frequency sub-band by perceptual noise substitution; and restoring the second frequency sub-band using the restored codebook codevector index information and the restored envelope information about the second frequency sub-band. - View Dependent Claims (22)
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23. A method of decoding a low bit-rate audio signal, the method comprising:
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dividing a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands and at least one second frequency sub-band other than the first frequency sub-band of the full-band audio signal; decoding and inversely quantizing the first frequency sub-bands of the full-band audio signal; decoding information as to whether a similar codevector in a codebook exists; if a similar codevector in the codebook exists, restoring codebook codevector index information that defines a fine structure of the first frequency sub-band and envelope information about the second frequency sub-band to help decode the structure of the similar second frequency sub-band; generating a codebook of codevectors to inversely vector quantize at least one second frequency sub-band or to decode the at least one second frequency sub-band by perceptual noise substitution using the first frequency sub-bands which are decoded and inversely quantized and restoring the at least one second frequency sub-band using the restored codebook index information that defines a fine structure of the first frequency sub-band and the restored envelope information about the second frequency sub-band; and if a similar codebook does not exist, restoring the envelope information and restoring the second frequency sub-band using a signal of a previous band and the restored envelope information. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. An apparatus to decode a low bit-rate audio signal, the apparatus comprising:
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a bit stream dividing unit which divides a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands and at least one second frequency sub-band other than the first frequency sub-bands of the full-band audio signal; a low frequency restoring unit which decodes and inversely quantizes the first frequency sub-bands of the full-band audio signal; a high frequency index/envelope restoring unit which restores codebook codevector index information which defines a fine structure of the first frequency sub-band and envelope information about the second frequency sub-band to help restore the structure of the similar second frequency sub-band; a codebook generating unit which generates a codebook of codevectors using the first frequency sub-band inversely quantized in the low frequency restoring unit to inversely vector quantize at least one second frequency sub-band or to decode at least one second frequency sub-band by perceptual noise substitution; and a high frequency restoring unit which restores the second frequency sub-band using the restored codebook codevector index information that defines a fine structure of the second frequency sub-band and the restored envelope information about the other frequency sub-band. - View Dependent Claims (31)
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32. An apparatus to decode a low bit-rate audio signal, the apparatus comprising:
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a bit stream dividing unit which divides a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands and at least one second frequency sub-band other than the first frequency sub-bands of the full-band audio signal; a low frequency restoring unit which decodes and inversely quantizes the first frequency sub-bands of the full-band audio signal; a codebook existence information restoring unit which decodes information as to whether a similar codevector of a codebook exists to inversely vector quantize at least one second frequency sub-band or to decode at least one second frequency sub-band by perceptual noise substitution; an index/envelope restoring unit which, if the similar codevector of the codebook exists, restores codebook codevector index information that defines a fine structure of the first frequency sub-band and envelope information about the second frequency sub-band to restore the similar second frequency sub-band; a first high frequency restoring unit which generates a codebook of codevectors using the first frequency sub-band which is decoded and inversely quantizes and restores the second frequency sub-band using the restored codebook index information and the restored envelope information about the second frequency sub-band; and a second high frequency restoring unit which, if a similar codevector does not exist, restores the envelope information and restores the second frequency sub-band using a signal of a previous band and the restored envelope information. - View Dependent Claims (33, 34, 35, 36, 37, 38)
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39. A non-transitory computer-readable medium having a computer executable program for a method of encoding a low bit-rate audio signal, the method comprising:
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quantizing and encoding a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands in a low frequency region of the full-band audio signal; generating a codebook of codevectors using the first frequency sub-bands in the low frequency region to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution; detecting an envelope of at least one second frequency sub-band of the full-band audio signal other than the first frequency sub-bands in a high frequency region and quantizing and encoding the envelope; selecting a codevector in the first frequency sub-band codebook that is most similar to the second frequency sub-band to be encoded from the codebook'"'"'s codevectors and determining a codebook codevector index which defines a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band; and generating a bit stream using encoded data generated in the encoding of the first frequency sub-band, the envelope, and the determined codebook codevector index.
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40. A non-transitory computer-readable medium having a computer executable program for a method of encoding a low bit-rate audio signal, the method comprising:
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quantizing and encoding a plurality of first frequency sub-bands in a low frequency region of the full-band audio signal having a plurality of frequency sub-bands; generating a codebook of codevectors using the first frequency sub-bands in the low frequency region to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution; detecting an envelope of at least one second frequency sub-bands of the full-band audio signal other than the first frequency sub-bands in a high-frequency region and quantizing and encoding the detected envelope of the second frequency sub-band; checking whether a codevector of a codebook having at least a predetermined similarity exists among the generated codevectors of the codebook with respect to the first frequency sub-band to help a similar second frequency sub-band to be encoded; if the similar codevector of the codebook exists, selecting the similar codevector of the codebook, determining a codebook codevector index which defines a fine structure of the first frequency sub-band to help encode the similar second frequency sub-band, and encoding the determined codebook index and information indicating that the similar codebook exists; if a similar codevector of the codebook does not exist, encoding information indicating that a similar codevector of the codebook does not exist; and generating a bit stream using encoded data generated in the encoding of the first frequency sub-band, the envelope of the second frequency sub-band, the determined codebook codevector index, and the information indicating that the similar codebook codevector does not exist.
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41. A non-transitory computer-readable medium having a computer executable program for a method of decoding a low bit-rate audio signal, the method comprising:
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dividing a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands and at least one second frequency sub-band higher than the highest first frequency sub-band of the full-band audio signal; decoding and inversely quantizing the first frequency sub-band of the full-band audio signal; restoring codebook codevector index information that defines a fine structure of the first frequency sub-band and envelope information about the second frequency sub-band to help restore the structure of the similar second frequency sub-band; generating a codebook of codevectors to inversely vector quantize at least one second frequency sub-band or to decode at least one second frequency sub-band by perceptual noise substitution using the inversely quantized first frequency sub-band; and restoring the second frequency sub-band using the restored codebook codevector index information and the restored envelope information about the second frequency sub-band.
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42. A non-transitory computer-readable medium having a computer executable program for a method of decoding a low bit-rate audio signal, the method comprising:
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dividing a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands and at least one second frequency sub-band higher than the highest first frequency sub-band of the full-band audio signal; decoding and inversely quantizing the first frequency sub-bands of the full-band audio signal; decoding information as to whether a similar codevector of a codebook exists; if a similar codevector of the codebook exists, restoring codebook codevector index information that defines the fine structure of the first frequency sub-band and envelope information about the second frequency sub-band to help restore the structure of the similar second frequency sub-band; generating a codebook of codevectors to inversely vector quantize at least one second frequency sub-band or to decode at least one second frequency sub-band by perceptual noise substitution using the first frequency sub-bands which are decoded and inversely quantized and restoring the second frequency sub-band using the restored codebook codevector index information and the restored envelope information about the second frequency sub-band; and if a similar codevector in the codebook does not exist, restoring the envelope information and restoring the second frequency sub-band using a signal of a previous band and the restored envelope information.
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43. A method of encoding a full-band audio signal, the method comprising:
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encoding a plurality of first frequency sub-bands of the full-band audio signal having a plurality of frequency sub-bands; generating a codebook of codevectors to vector quantize at least one high frequency sub-band or to encode at least one high frequency sub-band by perceptual noise substitution using the first frequency sub-bands; determining an envelope of at least one second frequency sub-band of the full-band audio signal which is different than the first frequency sub-band and encoding the envelope; selecting one of the generated codevectors of the codebook if it has a predetermined similarity to the second frequency sub-band; and encoding a bit stream with the encoded first frequency sub-bands, the encoded envelope, and one of an indication that a codevector of the codebook was selected with an index of the selected codebook which defines a fine structure of the first frequency sub-band to help encode the structure of the similar second frequency sub-band and an indication that a codebook was not selected.
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44. A method of decoding an audio signal, the method comprising:
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dividing a bit stream into a plurality of first frequency sub-bands of a full-band audio signal having a plurality of frequency sub-bands and at least one second frequency sub-band having envelope information of the full-band audio signal; decoding the first frequency sub-band and generating codevectors of a codebook to inversely quantize at least one high frequency sub-band or to decode at least one high frequency sub-band by perceptual noise substitution using the decoded first frequency sub-band; decoding codebook information which defines a fine structure of the first frequency sub-band indicating whether a codevector of the generated codebook has a similarity to the first frequency sub-band to help decode the structure of the similar second frequency sub-band; restoring the second frequency sub-band based on the codebook information using one of a generated codevectors of the codebook with the envelope information and a signal of a previous band with the envelope information.
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Specification