Encoder and decoder with improved quantizer using reserved quantizer level for small amplitude signals
AssigneeDolby Laboratories Licensing Corporation
InventorsCraig C. Todd, Mark F. Davis
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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.
Claims35
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.
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.
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.
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.
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.
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.
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.
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.
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.
A decoding method according to any one of claims 24 through 30 wherein generating dequantized signals generates signals having an N-bit two's complement representation, and wherein said reserved quantizing level is equal to -2.sup.N-1.
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.
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.
Dependencies are inferred from the claim text.