Encoder and decoder with improved quantizer using reserved quantizer level for small amplitude signals
First Claim
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1. An encoder of a signal comprisingreceiver means for receiving said signal, andquantizer means responsive to said receiver means for quantizing said signal according to a plurality of quantizing levels wherein said quantizer means uses a reserved quantizing level to represent signals having an amplitude significantly less than the smallest nonzero magnitude of said plurality of quantizing levels.
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Abstract
The invention relates in general to the quantization of digital signal information. More particularly, the invention relates to the reduction of perceptible effects of quantizing noise by reserving a special quantizing level for low-level signals in encoding and decoding applications.
31 Citations
35 Claims
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1. An encoder of a signal comprising
receiver means for receiving said signal, and quantizer means responsive to said receiver means for quantizing said signal according to a plurality of quantizing levels wherein said quantizer means uses a reserved quantizing level to represent signals having an amplitude significantly less than the smallest nonzero magnitude of said plurality of quantizing levels.
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3. An encoder of a signal comprising
receiver means for receiving said signal, ditherer means responsive to said receiver means for generating an intermediate signal by applying a dither component to said signal, and quantizer means responsive to said ditherer means for quantizing said intermediate signal according to a plurality of quantizing levels, wherein said quantizer means uses a reserved quantizing level to represent intermediate signals having an amplitude significantly less than the smallest nonzero magnitude of said plurality of quantizing levels.
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9. A decoder of a quantized signal generated by an encoder in response to a signal, said encoder comprising a quantizer having a plurality of quantizing levels and a reserved quantizing level to represent signals having an amplitude significantly less than a smallest nonzero magnitude of said plurality of quantizing levels, said decoder comprising
receiver means for receiving said quantized signal, and dequantizer means responsive to said receiver means for generating a dequantized signal, wherein a small amplitude dequantized signal is generated in response to portions of said quantized signal at said reserved quantizing level.
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11. A decoder of a quantized signal generated by an encoder in response to a signal, said encoder comprising a quantizer having a plurality of quantizing levels and a reserved quantizing level to represent signals having an amplitude significantly less than a smallest nonzero magnitude of said plurality of quantizing levels, said decoder comprising
dequantizer means responsive to said quantized signal for generating a dequantized signal, wherein a small amplitude dequantized signal is generated in response to portions of said quantized signal at said reserved quantizing level, and ditherer means responsive to said dequantizer means for generating a modified signal by applying a dither component to said dequantized signal.
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16. An encoding method of a signal comprising
receiving said signal, and quantizing said signal according to a plurality of quantizing levels, wherein a reserved quantizing level is used to represent signals having an amplitude significantly less than the smallest nonzero magnitude of said plurality of quantizing levels.
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17. An encoding method according to claim 17 wherein said quantizing uses said reserved quantizing level to represent signals having an amplitude substantially equal to or less than one-half said smallest nonzero magnitude.
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18. An encoding method of a signal comprising
receiving said signal, generating an intermediate signal by applying a dither component to said signal, and quantizing said-intermediate signal according to a plurality of quantizing levels, wherein a reserved quantizing level is used to represent intermediate signals having an amplitude significantly less than the smallest nonzero magnitude of said plurality of levels.
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24. A decoding method of a quantized signal generated by an encoding method in response to a signal, said encoding method comprising quantization having a plurality of quantizing levels and a reserved quantizing level to represent signals having an amplitude significantly less than a smallest nonzero magnitude of said plurality of quantizing levels, said decoding method comprising
receiving said quantized signal, and generating a dequantized signal, wherein a small amplitude dequantized signal is generated in response to portions of said quantized signal at said reserved quantizing level.
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26. A decoding method of a quantized signal generated by an encoding method in response to a signal, said encoding method comprising quantization having a plurality of quantizing levels and a reserved quantizing level to represent signals having an amplitude significantly less than a smallest nonzero magnitude of said plurality of quantizing levels, said decoding method comprising
generating a dequantized signal in response to said quantized signal, wherein a small amplitude dequantized signal is generated in response to portions of said quantized signal at said reserved quantizing level, and generating a modified signal by applying a dither component to said dequantized signal.
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31. An encoder of a signal comprising
a receiver, and a quantizer, responsive to said receiver, using a reserved quantizing level to represent signals having an amplitude significantly less than a smallest nonzero quantizing level magnitude.
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34. A decoder of a quantized signal generated by an encoder in response to a signal, said encoder comprising a quantizer using a reserved quantizing level to represent signals having an amplitude significantly less than a smallest nonzero magnitude quantizing level of said quantizer, said decoder comprising
a receiver, and a dequantizer responsive to said receiver, wherein a small amplitude dequantized signal is generated in response to portions of said quantized signal at said reserved quantizing level.
Specification