Methods and apparatus for gain controlling waveform elements ahead of an attack portion and waveform elements of a release portion
First Claim
1. A method for encoding a waveform signal, the waveform signal representative of audio or video data, comprising the steps of:
- detecting an attack portion of the waveform signal with an abruptly increased signal level;
detecting a release portion of the waveform signal with an abruptly decreased signal level;
adaptively selecting from among a plurality of gain control amounts a gain control amount at least for waveform elements ahead of the attack portion and waveform elements of the release portion, responsive to characteristics of the waveform signal, wherein the waveform signal is divided into a plurality of sub-blocks each having a plurality of waveform elements, and wherein the adaptive selection for each of the waveform elements ahead of attack portion and the waveform elements of the release portion of the waveform signal are based upon a respective ratio of a maximum amplitude value of continuous sub-blocks to a maximum amplitude value of a next following sub-block;
gain-controlling at least the waveform elements ahead of the attack portion and waveform elements of the release portion, using the selected gain control amount;
transforming said waveform signal into a plurality of frequency components; and
encoding control information for gain control and said frequency components.
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Accused Products
Abstract
A signal encoding method and apparatus for encoding input digital signals by so-called high efficiency encoding, and a recording medium having the encoded signals. An attack portion and a release portion of audio signals are detected and a gain control function is selected at least for waveform elements (waveform signals) of a signal portion ahead of the attack portion and waveform elements of the release portion from among plural gain control functions responsive to characteristics of the waveform signals. At least the waveform elements (waveform signals) ahead of the attack portion and the waveform elements of the release portion are gain controlled. The resulting gain-controlled audio signals are transformed into plural spectral components which are encoded along with the control information for gain control. With the present encoding method and apparatus, the encoding efficiency may be improved, while pre-echo and post-echo may be effectively prohibited and the sound quality may be prohibited from being deteriorated even for the high compression ratio.
84 Citations
32 Claims
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1. A method for encoding a waveform signal, the waveform signal representative of audio or video data, comprising the steps of:
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detecting an attack portion of the waveform signal with an abruptly increased signal level; detecting a release portion of the waveform signal with an abruptly decreased signal level; adaptively selecting from among a plurality of gain control amounts a gain control amount at least for waveform elements ahead of the attack portion and waveform elements of the release portion, responsive to characteristics of the waveform signal, wherein the waveform signal is divided into a plurality of sub-blocks each having a plurality of waveform elements, and wherein the adaptive selection for each of the waveform elements ahead of attack portion and the waveform elements of the release portion of the waveform signal are based upon a respective ratio of a maximum amplitude value of continuous sub-blocks to a maximum amplitude value of a next following sub-block; gain-controlling at least the waveform elements ahead of the attack portion and waveform elements of the release portion, using the selected gain control amount; transforming said waveform signal into a plurality of frequency components; and encoding control information for gain control and said frequency components. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for encoding a waveform signal, comprising:
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means for detecting an attack portion of the waveform signal with an abruptly increased signal level; means for detecting a release portion of the waveform signal with an abruptly decreased signal level; means for adaptively selecting from among a plurality of gain control amounts a gain control amount at least for waveform elements ahead of the attack portion and waveform elements of the release portion, responsive to characteristics of the waveform signal, wherein the waveform signal is divided into a plurality of sub-blocks each having a plurality of waveform elements, and wherein the adaptive selection for each of the waveform elements ahead of attack portion and the waveform elements of the release portion of the waveform signal are based upon a respective ratio of a maximum amplitude value of continuous sub-blocks to a maximum amplitude value of a next following sub-block; means for gain-controlling at least the waveform elements ahead of the attack portion and waveform elements of the release portion, using the selected gain control amount; means for transforming said waveform signal into a plurality of frequency components; and means for encoding control information for gain control and said frequency components. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for decoding encoded signals for restoring a waveform signal, wherein said encoded signals at least comprise an encoded version of a plurality of frequency components transformed from waveform elements and an encoded version of the control correction information for gain control correction for waveform elements ahead of an attack portion with an abruptly rising signal level and for waveform elements of a release portion with an abruptly decaying signal level, said encoded signals are decoded in order to take out the plural frequency components and the control correction information, said frequency components are transformed into waveform signals made up of plural waveform elements, comprising the steps of:
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performing gain control correction at least of the waveform elements ahead of the attack portion and the waveform elements of the release portion using the gain control correction amounts selected from among said plural gain control correction amounts on the basis of the control correction information; and restoring waveform signals from said waveform elements, wherein the control correction information is based upon a division of the waveform signal into a plurality of sub-blocks each having a plurality of waveform elements, and wherein the control correction information for each of the waveform elements ahead of attack portion and the waveform elements of the release portion of the waveform signal are based upon a respective ratio of a maximum amplitude value of continuous sub-blocks to a maximum amplitude value of a next following sub-block. - View Dependent Claims (16, 17, 18)
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19. An apparatus for decoding encoded signals for restoring a waveform signal, wherein said encoded signals at least comprise an encoded version of a plurality of frequency components transformed from waveform elements and an encoded version of the control correction information for gain control correction for waveform elements ahead of an attack portion with an abruptly rising signal level and for waveform elements of a release portion with an abruptly decaying signal level, comprising:
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decoding means for decoding said encoded signals in order to take out the plural frequency components and the control correction information; transform means for transforming said frequency components into waveform signals made up of plural waveform elements; means for performing gain control correction at least of the waveform elements ahead of the attack portion and the waveform elements of the release portion using the gain control correction amounts selected from among said plural gain control correction amounts on the basis of the control correction information; and
means for restoring waveform signals from said waveform elements, wherein the control correction information is based upon a division of the waveform signal into a plurality of sub-blocks each having a plurality of waveform elements, and wherein the control correction information for each of the waveform elements ahead of attack portion and the waveform elements of the release portion of the waveform signal are based upon a respective ratio of a maximum amplitude value of continuous sub-blocks to a maximum amplitude value of a next following sub-block. - View Dependent Claims (20, 21, 22)
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23. An information recording medium having an encoded digital signal recorded thereon, said information recording medium for controlling a reproducing apparatus wherein at least a part of said encoded digital signal is for controlling said reproducing apparatus, said recording medium being prepared by the steps of:
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detecting an attack portion of the waveform signal with an abruptly increased signal level; detecting a release portion of the waveform signal with an abruptly decreased signal level; adaptively selecting from among a plurality of gain control amounts a gain control amount at least for waveform elements ahead of the attack portion and waveform elements of the release portion, responsive to characteristics of the waveform signal, wherein the waveform signal is divided into a plurality of sub-blocks each having a plurality of waveform elements, and wherein the adaptive selection for each of the waveform elements ahead of attack portion and the waveform elements of the release portion of the waveform signal are based upon a respective ratio of a maximum amplitude value of continuous sub-blocks to a maximum amplitude value of a next following sub-block; gain-controlling at least the waveform elements ahead of the attack portion and waveform elements of the release portion, using the selected gain control amount; transforming said waveform signal into a plurality of frequency components; encoding the control information for gain control and said frequency components; and recording the encoded control information and frequency components on the information recording medium. - View Dependent Claims (24, 25, 26, 27)
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28. An information transmission method, comprising the steps of:
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transforming waveform elements into frequency components, said frequency components being obtained by transforming a gain controlled waveform signal using a gain control amount adaptively selected responsive to characteristics of the waveform signals from among a plurality of gain control amounts at least for waveform elements ahead of the attack portion where the waveform elements of the waveform signal rise abruptly in signal level and for waveform elements of the release portion where the waveform elements of the waveform signal decay abruptly in signal level, wherein the waveform signal is divided into a plurality of sub-blocks each having a plurality of waveform elements, and wherein the adaptive selection for each of the waveform elements ahead of attack portion and the waveform elements of the release portion of the waveform signal are based upon a respective ratio of a maximum amplitude value of continuous sub-blocks to a maximum amplitude value of a next following sub-block; encoding and transmitting said frequency components; and encoding and transmitting control information for gain control. - View Dependent Claims (29, 30, 31, 32)
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Specification