Digital system and method for compressing speech signals for storage and transmission
First Claim
1. A method for compressing a serial bit stream of speech encoded data for storage and transmission comprising the steps of:
- (a) storing the bits of said serial bit stream;
(b) reading the stored bits in fixed length frames;
(c) processing each frame of read bits to classify the frame as voiced, unvoiced or silence;
(d) determining the pitch for a frame classified as voiced;
(e) comparing, on a pitch basis, the bits of the present voiced frame with the bits of the preceding voiced frames to detect repetition;
(f) temporarily storing the repetition count, the pitch period, and the repetitive pitch bits; and
(g) repeating steps (b) through (f) to compress the serial bit stream that is temporarily stored.
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Accused Products
Abstract
The system and method of the invention operates upon a serial bit stream of speech encoded data by reading the data in fixed length frames. Each frame is classified as to whether the frame represents voiced, unvoiced, or a silence condition. For a voiced frame, the pitches are detected. The bits of the voiced frame are then compared with the bits of prior received voiced frames, on a pitch basis, so as to detect repetition. When repetition is detected, the repetition count, the pitch period, and the one set of the repetitive pitch bits are stored ready for transmission. The compressed data is reconstructed by utilizing a decoder which interprets the stored information and causes reinsertion of the repetitions.
35 Citations
10 Claims
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1. A method for compressing a serial bit stream of speech encoded data for storage and transmission comprising the steps of:
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(a) storing the bits of said serial bit stream; (b) reading the stored bits in fixed length frames; (c) processing each frame of read bits to classify the frame as voiced, unvoiced or silence; (d) determining the pitch for a frame classified as voiced; (e) comparing, on a pitch basis, the bits of the present voiced frame with the bits of the preceding voiced frames to detect repetition; (f) temporarily storing the repetition count, the pitch period, and the repetitive pitch bits; and (g) repeating steps (b) through (f) to compress the serial bit stream that is temporarily stored. - View Dependent Claims (2, 3, 4)
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5. A method for compressing a serial bit stream of speech encoded data for storage and transmission comprising the steps of:
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(a) storing the bits of said serial bit stream; (b) reading the stored bits in fixed length frames; (c) processing each frame of read bits to classify the frame as voiced, unvoiced or silence; (d) compressing the bits of a silent frame by storing one of the repeating bit patterns and a number corresponding to the number of times the bit pattern repeats in a frame; (e) compressing the bits of a voiced frame; (f) comparing, on a pitch basis, the bits of the present voiced frame with the bits of the preceding voiced frames to detect repetition; (g) temporarily storing the repetition count, the pitch period, and the repetitive pitch bits; and (h) repeating steps (b) through (g) to compress the serial bit stream that is temporarily stored.
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6. A system for compressing a serial bit stream of speech encoded data comprising:
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storage means for temporarily storing the serial bit stream of speech encoded data; receiver means operatively coupled to said storage means for reading the serial bit stream from said storage means in fixed length frames; compression means coupled to said receiver means for classifying each frame as voiced, unvoiced or silence and for compressing a voiced frame by recording the number of times that a pitch occurs in each preceding frame and the pattern of the repetitive bits; second storage means for temporarily storing the compressed frames from said compression means; and decoding means coupled to said second storage means for decompressing the compressed frames to reconstruct said serial bit stream of speech encoded data. - View Dependent Claims (7, 8, 9, 10)
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Specification