System and method for performing voice compression
First Claim
1. A method of voice compression comprising the steps of:
- performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal in accordance with a speech compression procedure;
storing the intermediate signal;
performing a second type of compression different from the first type on said stored intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and
wherein said first type of compression is of a kind that causes loss of a portion of the information contained in the intermediate signal with respect to the voice signal, and said second type of compression is of a kind that causes no loss of information contained in the output signal with respect to the intermediate signal.
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Abstract
Voice compression is performed in multiple stages to increase the overall compression between the incoming analog voice signal and the resulting digitized voice signal over that which would be obtained if only a single stage of compression were to be used. A first type of compression is performed on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal, and a second, different type of compression is performed on the intermediate signal to produce an output signal that is compressed still further. As a result, compression better than 1920 bits per second (and approaching 960 bits per second) are obtained without sacrificing the intelligibility of the subsequently reconstructed analog voice signal. Voice compression is also performed by recognizing redundant portions of said voice signal, such as silence, and replacing such redundant portions with a special code in said compressed signal. Among other advantages, the higher total compression allows speech to be transmitted in far less time than would otherwise be possible, thereby reducing expense.
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Citations
31 Claims
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1. A method of voice compression comprising the steps of:
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performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal in accordance with a speech compression procedure; storing the intermediate signal; performing a second type of compression different from the first type on said stored intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said first type of compression is of a kind that causes loss of a portion of the information contained in the intermediate signal with respect to the voice signal, and said second type of compression is of a kind that causes no loss of information contained in the output signal with respect to the intermediate signal.
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2. A method of voice compression comprising the steps of:
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performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal; storing the intermediate signal; performing a second type of compression different from the first type on said stored intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said output signal is compressed in time with respect to said voice signal.
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3. A method of voice compression comprising the steps of:
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performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal in accordance with a speech compression procedure; performing a second type of compression different from the first type on said intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and storing said intermediate signal as a data file prior to performing said second type of compression.
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5. A method of voice compression comprising the steps of:
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performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal; performing a second type of compression different from the first type on said intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said voice signal includes speech interspersed with silence, and said first type of compression produces said intermediate signal as a sequence of frames each of which corresponds in time to a portion of said voice signal and said voice signal includes data representative of said portion of said voice signal, and further comprising detecting at least one of said frames which corresponds to a portion of said voice signal that contains silence, replacing said at least one of said frames in said sequence with a binary code that indicates silence, and thereafter performing said second type of compression on said sequence. - View Dependent Claims (6)
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7. A method of voice compression comprising the steps of:
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performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal; performing a second type of compression different from the first type on said intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said first type of compression produces said intermediate signal as a sequence of frames each of which corresponds in time to a portion of said voice signal and contains data that represents a plurality of characteristics of said voice signal, said data for at least one of said characteristics being interleaved with said date for at least one other of said characteristics in said frame, and further comprising; deinterleaving said delta so that said data for each one of said characteristics appears together in said frame, and thereafter performing said second type of compression on said sequence. - View Dependent Claims (4, 8)
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9. A method of voice compression comprising the steps of:
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performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal; performing a second type of compression different from the first type on said intermediate signal to produce an output signal that is compressed with respect to the intermediate signal;
addwherein said first type of compression produces said intermediate signal as a sequence of frames each of which corresponds in time to a portion of said voice signal and contains data that represents information contained in said portion of said voice signal and data that does not represent said information, and further comprising; removing said data that does not represent said information from each one of said frames, and thereafter performing said second type of compression on said sequence.
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10. A method of voice compression comprising the steps of:
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performing a first type of compression on a voice signal to produce an intermediate signal that is compressed with respect to the voice signal; performing a second type of compression different from the first type on said intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said first type of compression produces said intermediate signal as a sequence of frames each of which corresponds in time to a portion of said voice signal and includes a plurality of bits of data at least some of which represent information contained in said portion of said voice signal, each said frame being a non-interger number of bytes in length, and further comprising; adding a selected number of bits to each said frame to increase the length thereof to an integer number of bytes, and thereafter performing said second type of compression on said sequence.
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11. A method of performing compression on a voice signal that includes redundant signal information, comprising the steps of:
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performing compression on a voice signal to produce a first compressed signal; detecting at least one portion of said compressed signal that corresponds to a portion of said voice signal that contains only said redundant signal information; replacing said at least one portion of said first compressed signal with a binary code that indicates said redundant signal information. - View Dependent Claims (12, 13, 14, 15, 16)
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17. Voice compression apparatus comprising:
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a first compressor for performing a first type of compression on a voice signal to produce an intermediate signal that is a signal in accordance with a speech compression procedure; a memory for storing the intermediate signal; a second compressor for performing a second type of compression different from the first type on the stored intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said first compressor causes loss of a portion of the information contained in the intermediate signal with respect to the voice signal, and said second compressor causes no loss of information contained in the output signal with respect to the intermediate signal.
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18. Voice compression apparatus comprising:
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a first compressor for performing a first type of compression on a voice signal to produce an intermediate signal that is a signal in accordance with a speech compression procedure; a second compressor for performing a second type of compression different from the first type on the intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and a memory for storing said intermediate signal as a data file. - View Dependent Claims (19)
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20. Voice compression apparatus comprising:
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a first compressor for performing a first type of compression on a voice signal to produce an intermediate signal that is a signal; a second compressor for performing a second type of compression different from the first type on the intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said voice signal includes speech interspersed with silence, and said first compressor produces said intermediate signal as a sequence of frames each of which corresponds in time to a portion said voice signal and includes data representative of said portion of said voice signal, and further comprising; a detector for detecting at least one of said frames which corresponds to a portion of said voice signal that contains substantially only silence, means for replacing said at least one of said frames in said sequence with a binary code that indicates silence, and means for thereafter applying said sequence to said second compressor. - View Dependent Claims (21)
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22. Voice compression apparatus comprising;
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a first compressor for performing a first type of compression on a voice signal to produce an intermediate signal that is a signal; a second compressor for performing a second type of compression on the intermediate signal different from the first type to produce an output signal that is compressed with respect to the intermediate signal; and wherein said first compressor produces said intermediate signal as a sequence of frames each of which corresponds to a portion of said voice signal and contains data that represents a plurality of characteristics of said voice signal, said data for at least one of said characteristics being interleaved with said data for at least one other of said characteristics in said frame, and further comprising; means for deinterleaving said data so that said data for each one of said characteristics appears together in said frame, and means for thereafter applying said sequence to said second compressor. - View Dependent Claims (23)
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24. Voice compression apparatus comprising;
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a first compressor for performing a first type of compression on a voice signal to produce an intermediate signal that is a signal; a second compressor for performing a second type of compression different from the first type on the intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said first compressor produces said intermediate signal as a sequence of frames each of which corresponds to a portion of said voice signal and contains data that represents information contained in said portion of said voice signal and data that does not represent said information, and further comprising; means for removing said data that does not represent said information from each one of said frames, and means for thereafter applying said sequence to said second compressor.
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25. Voice compression apparatus comprising:
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a first compressor for performing a first type of compression on a voice signal to produce an intermediate signal that is a signal; a second compressor for performing a second type of compression different from the first type on the intermediate signal to produce an output signal that is compressed with respect to the intermediate signal; and wherein said first compressor produces said intermediate signal as a sequence of frames each of which corresponds to a portion of said voice signal and includes a plurality of bits of data at least some of which represent information contained in said portion of said voice signal, each said frame being a non-integer number of bytes in length, and further comprising; circuitry for adding a selected number of bits to each said frame to increase the length thereof to an integer number of bytes, and means for thereafter applying said sequence to said second compressor.
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26. Apparatus for performing compression on a voice signal that includes speech interspersed with redundant signal information, comprising:
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a compressor for performing compression on a voice signal to produce a first compressed signal that is compressed with respect to the voice signal, a detector for detecting at least one portion of said first compressed signal that corresponds to a portion of said voice signal that contains substantially only said redundant signal information, means for replacing said at least one portion of said first compressed signal with a binary code that indicates said redundant signal information. - View Dependent Claims (27, 28, 29, 30, 31)
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Specification