Apparatus for encoding digital data with reduction of perceptible noise
First Claim
1. Apparatus for encoding a digital signal comprised of a plurality of samples, said apparatus comprising:
- frequency dividing means for dividing said digital signal comprised of said plurality of samples into a plurality of frequency divided signals within respective frequency bands;
encoding means for encoding said frequency divided signals including block segmentation means for segmenting each of said frequency divided signals into respective size blocks each having a respective number of said samples, orthogonal transformation means for orthogonally transforming said blocks to form coefficient data, and quantization means for quantizing said coefficient data with a number of bits to form an encoded digital signal;
transient detection means receiving at least the one of said plurality of frequency divided signals within the lowest of said frequency bands for detecting a transient in the received frequency divided signal within the lowest frequency band and for generating an output signal indicating that said transient has been detected; and
control means responsive to said output signal from said transient detection means for controlling the encoding performed by said encoding means of at least said frequency divided signal within said lowest frequency band so as to reduce the perceptibility of noise in the encoded digital signal.
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Abstract
Apparatus for efficiently encoding a digital signal divides the digital signal into a number of signals within respective predetermined frequency bands which are segmented into blocks which, in turn, are orthogonally transformed so as to form coefficient data. The coefficient data is then quantized. A detection circuit detects whether at least the divided signal within the lowest frequency band contains a transient. If a transient is detected, a control circuit controls the encoding processing of a least the divided signal within the lowest frequency band by, for example, increasing the number of bits used for quantizing, reducing the block size, and/or reducing the signal level so as to reduce the perceptibility of noise in the processed signal.
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Citations
45 Claims
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1. Apparatus for encoding a digital signal comprised of a plurality of samples, said apparatus comprising:
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frequency dividing means for dividing said digital signal comprised of said plurality of samples into a plurality of frequency divided signals within respective frequency bands; encoding means for encoding said frequency divided signals including block segmentation means for segmenting each of said frequency divided signals into respective size blocks each having a respective number of said samples, orthogonal transformation means for orthogonally transforming said blocks to form coefficient data, and quantization means for quantizing said coefficient data with a number of bits to form an encoded digital signal; transient detection means receiving at least the one of said plurality of frequency divided signals within the lowest of said frequency bands for detecting a transient in the received frequency divided signal within the lowest frequency band and for generating an output signal indicating that said transient has been detected; and control means responsive to said output signal from said transient detection means for controlling the encoding performed by said encoding means of at least said frequency divided signal within said lowest frequency band so as to reduce the perceptibility of noise in the encoded digital signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. Apparatus for encoding a digital signal comprised of a plurality of samples, said apparatus comprising:
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encoding means for encoding said digital signal including block segmentation means for segmenting said signal into blocks each having a respective number of said samples, transformation means for transforming said blocks from a time domain to a frequency domain so as to form coefficient data, and quantization means for quantizing said coefficient data with a number of bits to form an encoded signal; transient detection means for detecting a transient in the received digital signal, including means receiving said blocks of samples for dividing said blocks into subblocks, means for determining a signal characteristic for each subblock, means for comparing the respective determined signal characteristics of the subblocks making up one of said blocks and means for generating an output signal indicating that said transient has been detected on the basis of a comparison of the respective determined signal characteristics; and control means responsive to said output signal from said transient detection means for controlling the encoding of said digital signal performed by said encoding means so as to reduce the perceptibility of noise in the encoded signal. - View Dependent Claims (17)
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18. Apparatus for encoding a digital signal comprised of a plurality of samples, said apparatus comprising:
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frequency dividing means for dividing said digital signal comprised of said plurality of samples into a plurality of frequency divided signals within respective frequency bands; and encoding means for encoding said frequency divided signals including block segmentation means for segmenting each of said frequency divided signals into respective size blocks each having a respective number of samples, transformation means for transforming said blocks from a time domain to a frequency domain so as to form coefficient data, and quantization means for quantizing said coefficient data with a number of bits to form an encoded digital signal. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A method of encoding a digital signal comprised of a plurality of samples, comprising the steps of:
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dividing said digital signal comprised of said plurality of samples into a plurality of frequency divided signals within respective frequency bands; segmenting each of said frequency divided signals into respective size blocks each having a respective number of samples, transforming said blocks from a time domain to a frequency domain so as to form coefficient data, and quantizing said coefficient data with a number of bits to form an encoded signal. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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Specification