Linear predictive analysis-by-synthesis encoding method and encoder
DCFirst Claim
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1. A linear predictive analysis-by-synthesis coding method, including the steps ofdetermining optimum gains of a plurality of subframes;
- collectively vector quantizing said optimum gains; and
updating internal encoder states using said collective vector quantized gains.
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Abstract
A linear predictive analysis-by-synthesis encoder includes a search algorithm block (50) and a vector quantizer (58) for vector quantizing optimal gains from a plurality of subframes in a frame. The internal encoder states are updated (50, 52, 54, 56) using the vector quantized gains.
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14 Claims
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1. A linear predictive analysis-by-synthesis coding method, including the steps of
determining optimum gains of a plurality of subframes; -
collectively vector quantizing said optimum gains; and
updating internal encoder states using said collective vector quantized gains. - View Dependent Claims (2, 3, 4, 5, 6, 7)
storing an internal encoder state after encoding of a subframe with optimal gains; restoring said internal encoder state after vector quantization of gains from several subframes; and
updating said internal encoder states by using determined codebook vectors and said vector quantized gains.
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3. The method of claim 2, wherein said internal encoder state include an adaptive codebook state, a synthesis filter state and a weighting filter state.
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4. The method of claim 1, 2 or 3, wherein gains from 2 subframes are vector quantized.
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5. The method of claim 1, 2 or 3, wherein all gains from all subframes of said frame are vector quantized.
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6. The method of claim 1, including the steps of:
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weighting error contributions from different subframes by weighting factors; and
minimizing the sum of the weighted error contributions.
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7. The method of claim 6, wherein each weighting factor depends on the energy of its corresponding subframe.
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8. A linear predictive analysis-by-synthesis encoder, including
a search algorithm block for determining optimum gains of a plurality of subframes; -
a vector quantizer for collectively vector quantizing said optimum gains; and
means for updating internal encoder states using said collective vector quantized gains. - View Dependent Claims (9, 10, 11, 12, 13, 14)
means for storing an internal encoder state after encoding of a subframe with optimal gains; means for restoring said internal encoder state after vector quantization of gains from several subframes; and
means for updating said internal encoder states by using determined codebook vectors and said vector quantized gains.
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10. The encoder of claim 9, wherein said means for storing said internal encoder state includes an adaptive codebook state storing means, a synthesis filter state storing means and a weighting filter state storing means.
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11. The encoder of claim 8, 9 or 10, including means for vector quantizing gains from 2 subframes.
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12. The encoder of claim 8, 9 or 10, including means for vector quantizing all gains from all subframes of a speech frame.
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13. The encoder of claim 8, including
means (58) for weighting error contributions from different subframes by weighting factors and minimizing the sum of the weighted error contributions. -
14. The encoder of claim 13, including means for determining weighting factors that depend on the energy of corresponding subframes.
Specification