TECHNIQUE FOR ENCODING/DECODING OF CODEBOOK INDICES FOR QUANTIZED MDCT SPECTRUM IN SCALABLE SPEECH AND AUDIO CODECS
First Claim
1. A method for encoding in a scalable speech and audio codec, comprising:
- obtaining a residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal;
transforming the residual signal at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum;
dividing the transform spectrum into a plurality of spectral bands, each spectral band having a plurality of spectral lines;
selecting a plurality of different codebooks for encoding the spectral bands, where the codebooks have associated codebook indices;
performing vector quantization on spectral lines in each spectral band using the selected codebooks to obtain vector quantized indices;
encoding the codebook indices;
encoding the vector quantized indices; and
forming a bitstream of the encoded codebook indices and encoded vector quantized indices to represent the quantized transform spectrum.
1 Assignment
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Accused Products
Abstract
Codebook indices for a scalable speech and audio codec may be efficiently encoded based on anticipated probability distributions for such codebook indices. A residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer may be obtained, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal. The residual signal may be transformed at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum. The transform spectrum is divided into a plurality of spectral bands, where each spectral band having a plurality of spectral lines. A plurality of different codebooks are then selected for encoding the spectral bands, where each codebook is associated with a codebook index. A plurality of codebook indices associated with the selected codebooks are then encoded together to obtain a descriptor code that more compactly represents the codebook indices.
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Citations
39 Claims
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1. A method for encoding in a scalable speech and audio codec, comprising:
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obtaining a residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal; transforming the residual signal at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum; dividing the transform spectrum into a plurality of spectral bands, each spectral band having a plurality of spectral lines; selecting a plurality of different codebooks for encoding the spectral bands, where the codebooks have associated codebook indices; performing vector quantization on spectral lines in each spectral band using the selected codebooks to obtain vector quantized indices; encoding the codebook indices; encoding the vector quantized indices; and forming a bitstream of the encoded codebook indices and encoded vector quantized indices to represent the quantized transform spectrum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A scalable speech and audio encoder device, comprising:
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a Discrete Cosine Transform (DCT)-type transform layer module adapted to obtain a residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal; transform the residual signal at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum; a band selector for dividing the transform spectrum into a plurality of spectral bands, each spectral band having a plurality of spectral lines; a codebook selector for selecting a plurality of different codebooks for encoding the spectral bands, where the codebooks have associated codebook indices; a vector quantizer for performing vector quantization on spectral lines in each spectral band using the selected codebooks to obtain vector quantized indices; a codebook indices encoder for encoding a plurality of codebooks indices together; a vector quantized indices encoder for encoding the vector and a transmitter for transmitting a bitstream of the encoded codebook indices and encoded vector quantized indices to represent the quantized transform spectrum. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A scalable speech and audio encoder device, comprising:
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means for obtaining a residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal; means for transforming the residual signal at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum; means for dividing the transform spectrum into a plurality of spectral bands, each spectral band having a plurality of spectral lines; means for selecting a plurality of different codebooks for encoding the spectral bands, where the codebooks have associated codebook indices; means for performing vector quantization on spectral lines in each spectral band using the selected codebooks to obtain vector quantized indices; means for encoding the codebook indices; means for encoding the vector quantized indices; and means for forming a bitstream of the encoded codebook indices and encoded vector quantized indices to represent the quantized transform spectrum.
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19. A processor including a scalable speech and audio encoding circuit adapted to:
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obtain a residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal; transform the residual signal at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum; divide the transform spectrum into a plurality of spectral bands, each spectral band having a plurality of spectral lines; select a plurality of different codebooks for encoding the spectral bands, where the codebooks have associated codebook indices; perform vector quantization on spectral lines in each spectral band using the selected codebooks to obtain vector quantized indices; encode the codebook indices; encode the vector quantized indices; and form a bitstream of the encoded codebook indices and encoded vector quantized indices to represent the quantized transform spectrum.
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20. A machine-readable medium comprising instructions operational for scalable speech and audio encoding, which when executed by one or more processors causes the processors to:
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obtain a residual signal from a Code Excited Linear Prediction (CELP)-based encoding layer, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal; transform the residual signal at a Discrete Cosine Transform (DCT)-type transform layer to obtain a corresponding transform spectrum; divide the transform spectrum into a plurality of spectral bands, each spectral band having a plurality of spectral lines; select a plurality of different codebooks for encoding the spectral bands, where the codebooks have associated codebook indices; perform vector quantization on spectral lines in each spectral band using the selected codebooks to obtain vector quantized indices; encode the codebook indices; encode the vector quantized indices; and form a bitstream of the encoded codebook indices and encoded vector quantized indices to represent the quantized transform spectrum.
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21. A method for decoding in a scalable speech and audio codec, comprising:
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obtaining a bitstream having a plurality of encoded codebook indices and a plurality of encoded vector quantized indices that represent a quantized transform spectrum of a residual signal, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal from a Code Excited Linear Prediction (CELP)-based encoding layer; decoding the plurality of encoded codebook indices to obtain decoded codebook indices for a plurality of spectral bands; decoding the plurality of encoded vector quantized indices to obtain decoded vector quantized indices for the plurality of spectral bands; and synthesizing the plurality of spectral bands using the decoded codebook indices and decoded vector quantized indices to obtain a reconstructed version of the residual signal at an Inverse Discrete Cosine Transform (IDCT)-type inverse transform layer. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A scalable speech and audio decoder device, comprising:
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a receiver to obtain a bitstream having a plurality of encoded codebook indices and a plurality of encoded vector quantized indices that represent a quantized transform spectrum of a residual signal, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal from a Code Excited Linear Prediction (CELP)-based encoding layer; a codebook index decoder for decoding the plurality of encoded codebook indices to obtain decoded codebook indices for a plurality of spectral bands; a vector quantized index decoder for decoding the plurality of encoded vector quantized indices to obtain decoded vector quantized indices for the plurality of spectral bands; and a band synthesizer for synthesizing the plurality of spectral bands using the decoded codebook indices and decoded vector quantized indices to obtain a reconstructed version of the residual signal at an Inverse Discrete Cosine Transform (IDCT)-type inverse transform layer. - View Dependent Claims (32, 33, 34, 35, 36)
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37. A scalable speech and audio decoder device, comprising:
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means for obtaining a bitstream having a plurality of encoded codebook indices and a plurality of encoded vector quantized indices that represent a quantized transform spectrum of a residual signal, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal from a Code Excited Linear Prediction (CELP)-based encoding layer; means for decoding the plurality of encoded codebook indices to obtain decoded codebook indices for a plurality of spectral bands; means for decoding the plurality of encoded vector quantized indices to obtain decoded vector quantized indices for the plurality of spectral bands; and means for synthesizing the plurality of spectral bands using the decoded codebook indices and decoded vector quantized indices to obtain a reconstructed version of the residual signal at an Inverse Discrete Cosine Transform (IDCT)-type inverse transform layer.
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38. A processor including a scalable speech and audio decoding circuit adapted to:
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obtain a bitstream having a plurality of encoded codebook indices and a plurality of encoded vector quantized indices that represent a quantized transform spectrum of a residual signal, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal from a Code Excited Linear Prediction (CELP)-based encoding layer; decode the plurality of encoded codebook indices to obtain decoded codebook indices for a plurality of spectral bands; decode the plurality of encoded vector quantized indices to obtain decoded vector quantized indices for the plurality of spectral bands; and synthesize the plurality of spectral bands using the decoded codebook indices and decoded vector quantized indices to obtain a reconstructed version of the residual signal at an Inverse Discrete Cosine Transform (IDCT)-type inverse transform layer.
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39. A machine-readable medium comprising instructions operational for scalable speech and audio decoding, which when executed by one or more processors causes the processors to:
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obtain a bitstream having a plurality of encoded codebook indices and a plurality of encoded vector quantized indices that represent a quantized transform spectrum of a residual signal, where the residual signal is a difference between an original audio signal and a reconstructed version of the original audio signal from a Code Excited Linear Prediction (CELP)-based encoding layer; decode the plurality of encoded codebook indices to obtain decoded codebook indices for a plurality of spectral bands; decode the plurality of encoded vector quantized indices to obtain decoded vector quantized indices for the plurality of spectral bands; and synthesize the plurality of spectral bands using the decoded codebook indices and decoded vector quantized indices to obtain a reconstructed version of the residual signal at an Inverse Discrete Cosine Transform (IDCT)-type inverse transform layer.
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Specification