US5451954A
Expired / Lapsed
US
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Quantization noise suppression for encoder/decoder system
Assignee: Dolby Laboratories Licensing Corp
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Filing: 1993-08-04
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Granted: 1995-09-19
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Expires: 2013-08-04
Abstract
Abstract The invention relates in general to low bit-rate encoding and decoding of information such as audio information. More particularly, the invention relates to the suppression of quantizing noise which results from low bit-rate encoding and decoding of signal events such as transients. An encoder identifies intervals of an input signal in which a decoder is likely to generate audible artifacts caused by quantizing errors. Indications of these intervals are passed in the encoded signal to the decoder. The decoder uses these indications to eliminate quantizing artifacts by suppressing corresponding intervals in the output signal.
Inventors
- 👤 Mark F. Davis
- 👤 Craig C. Todd
- 👤 Grant A. Davidson
- 👤 Stephen D. Vernon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:13
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; H04B1/665; H04N; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/60; H04N5/00; H04N5/14; H04N5/21
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
116 words
An encoder of an input signal comprising signal samples, said encoder comprising receiver means for receiving said signal samples and for generating an auxiliary signal in response thereto, said auxiliary signal comprising subblocks of one or more samples, detector means for detecting transients within said auxiliary signal, selection means for generating side information indicating the position of one or more of said subblocks in proximity to one or more of said transients, filter bank means for generating subband information in response to said signal samples, quantizer means for generating quantized information by quantizing said subband information, and formatter means for assembling said quantized information and said side information into a form suitable for transmission or storage.
Claim 2
Dependent Claim
116 words
An encoder of an input signal comprising signal samples, said encoder comprising receiver means for receiving said signal samples and for generating an auxiliary signal in response thereto, said auxiliary signal comprising subblocks of one or more samples, detector means for detecting transients within said auxiliary signal, selection means for generating side information indicating the position of one or more of said subblocks in proximity to one or more of said transients, filter bank means for generating subband information in response to said signal samples, quantizer means for generating quantized information by quantizing said subband information, and formatter means for assembling said quantized information and said side information into a form suitable for transmission or storage.
Claim 3
Dependent Claim
30 words
An encoder according to claim 1 wherein said detector means compares a transient threshold to a difference between a measure of subblock amplitudes of a respective pair of said subblocks.
Claim 4
Dependent Claim
24 words
An encoder according to claim 2 wherein said measure of subblock amplitude is the amplitude of the largest magnitude sample in the respective subblock.
Claim 5
Dependent Claim
20 words
An encoder according to claim 2 wherein said transient threshold represents a change in amplitude substantially equal to 14 dB.
Claim 6
Dependent Claim
27 words
An encoder according to claim 1 or 2 wherein the length of said subblocks is commensurate to the pre-temporal psychoacoustic masking interval of the human auditory system.
Claim 7
Dependent Claim
63 words
An encoder according to claim 1 or 2 wherein said selection means generates side information indicating the position of one or more intervals, each interval comprising one or a plurality of adjoining subblocks immediately adjacent to a respective one of said one or more transients, wherein a measure of subblock amplitude of all subblocks within said interval do not exceed a small-amplitude threshold.
Claim 8
Dependent Claim
24 words
An encoder according to claim 6 wherein said measure of subblock amplitude is the amplitude of the largest magnitude sample in the respective subblock.
Claim 9
Dependent Claim
20 words
An encoder according to claim 6 wherein said small-amplitude threshold decreases as a function of distance from a respective transient.
Claim 10
Dependent Claim
45 words
An encoder according to claim 8 wherein the length of said subblocks is commensurate to the pre-temporal psychoacoustic masking interval of the human auditory system, and wherein said small-amplitude threshold decreases at a rate substantially equal to 3 dB across the length of each subblock.
Claim 11
Dependent Claim
38 words
An encoder according to claim 8 wherein the length of said subblocks is substantially equal to one millisecond, and wherein said small-amplitude threshold decreases at a rate substantially equal to 3 dB across the length of each subblock.
Claim 12
Dependent Claim
21 words
An encoder according to claim 6 wherein each of said intervals comprise one or more subblocks prior to a respective transient.
Claim 13
Dependent Claim
24 words
An encoder according to claim 1 or 2 wherein said receiver means generates said auxiliary signal by applying a filter to said signal samples.
Claim 14
Dependent Claim
22 words
An encoder according to claim 12 wherein said filter is a high-pass filter with a cutoff frequency substantially equal to 2 kHz.
Claim 15
Dependent Claim
32 words
An encoder according to claim 13 wherein said filter is a band-pass filter with a first cutoff frequency substantially equal to 2 kHz a second cutoff frequency substantially equal to 8 kHz.
Claim 16
Dependent Claim
108 words
A decoder of encoded information representing an input signal, said decoder comprising deformatter means for receiving said encoded signal and for extracting quantized information and side information therefrom, wherein said side information indicates one or more positions within said input signal, dequantizer means for dequantizing said quantized information into recovered subband information, inverse filter bank means for generating recovered signal samples in response to said recovered subband information, and suppressor means for generating an output signal in response to said recovered signal samples by suppressing selected ones of said recovered signal samples, said samples selected in response to said one or more positions indicated by said side information.
Claim 17
Dependent Claim
108 words
A decoder of encoded information representing an input signal, said decoder comprising deformatter means for receiving said encoded signal and for extracting quantized information and side information therefrom, wherein said side information indicates one or more positions within said input signal, dequantizer means for dequantizing said quantized information into recovered subband information, inverse filter bank means for generating recovered signal samples in response to said recovered subband information, and suppressor means for generating an output signal in response to said recovered signal samples by suppressing selected ones of said recovered signal samples, said samples selected in response to said one or more positions indicated by said side information.
Claim 18
Dependent Claim
18 words
A decoder according to claim 15 wherein said suppressor means sets said selected samples to a predefined value.
Claim 19
Dependent Claim
12 words
A decoder according to claim 16 wherein said predefined value is zero.
Claim 20
Dependent Claim
22 words
A decoder according to claim 15 wherein said suppressor means reduces the amplitude of said selected samples by applying a scale factor.
Claim 21
Dependent Claim
17 words
A decoder according to claim 15 wherein said suppressor means applies a filter to said selected samples.
Claim 22
Dependent Claim
58 words
A decoder according to claim 15 wherein said suppressor means comprises means for passing said recovered signal samples through a filter and through a matching delay element in parallel with said filter, and switching means for generating said output signal by switching between the outputs of said filter and said delay element in response to said side information.
Claim 23
Dependent Claim
23 words
A decoder according to claim 20 wherein said switching means is a cross-fade between the outputs of said filter and said delay element.
Claim 24
Dependent Claim
98 words
An encoding method of an input signal comprising signal samples, said encoding method comprising receiving said signal samples and generating an auxiliary signal in response thereto, said auxiliary signal comprising subblocks of one or more samples, detecting transients within said auxiliary signal, generating side information indicating the position of one or more of said subblocks in proximity to one or more of said transients, generating subband information in response to said signal samples, generating quantized information by quantizing said subband information, and assembling said quantized information and said side information into a form suitable for transmission or storage.
Claim 25
Dependent Claim
98 words
An encoding method of an input signal comprising signal samples, said encoding method comprising receiving said signal samples and generating an auxiliary signal in response thereto, said auxiliary signal comprising subblocks of one or more samples, detecting transients within said auxiliary signal, generating side information indicating the position of one or more of said subblocks in proximity to one or more of said transients, generating subband information in response to said signal samples, generating quantized information by quantizing said subband information, and assembling said quantized information and said side information into a form suitable for transmission or storage.
Claim 26
Dependent Claim
95 words
A decoding method of encoded information representing an input signal, said decoding method comprising receiving said encoded signal and extracting quantized information and side information therefrom, wherein said side information indicates one or more positions within said input signal, dequantizing said quantized information into recovered subband information, generating recovered signal samples in response to said recovered subband information, and generating an output signal in response to said recovered signal samples by suppressing selected ones of said recovered signal samples, said samples selected in response to said one or more positions indicated by said side information.
Claim 27
Dependent Claim
95 words
A decoding method of encoded information representing an input signal, said decoding method comprising receiving said encoded signal and extracting quantized information and side information therefrom, wherein said side information indicates one or more positions within said input signal, dequantizing said quantized information into recovered subband information, generating recovered signal samples in response to said recovered subband information, and generating an output signal in response to said recovered signal samples by suppressing selected ones of said recovered signal samples, said samples selected in response to said one or more positions indicated by said side information.
References Cited (Backward Citations)
US4464783A
Cited
EP0193143B1
Cited
EP0251028A2
Cited
WO1989011759A1
Cited
US5109417A
Cited
EP0446031A2
Cited
WO1992017884A1
Cited
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