Method and apparatus for using coding scheme selection patterns in a predictive speech coder to reduce sensitivity to frame error conditions
First Claim
1. A speech coder, comprising:
- at least one predictive coding mode;
at least one less-predictive coding mode; and
a processor coupled to the at least one predictive coding mode and to the at least one less-predictive coding mode, the processor being configured to cause successive speech frames to be coded by selected coding modes in accordance with at least one pattern, the at least one pattern including at least one speech frame coded with a less-predictive coding mode.
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Abstract
A method and apparatus for using coding scheme selection patterns in a predictive speech coder to reduce sensitivity to frame error conditions includes a speech coder configured to select from among various predictive coding modes. After a predefined number of speech frames have been predictively coded, the speech coder codes one frame with a nonpredictive coding mode or a mildly predictive coding mode. The predefined number of frames can be determined in advance from the subjective standpoint of a listener. The predefined number of frames may be varied periodically. An average coding bit rate may be maintained for the speech coder by ensuring that an average coding bit rate is maintained for each successive pattern, or group, of predictively coded speech frames including at least one nonpredictively coded or mildly predictively coded speech frame.
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Citations
33 Claims
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1. A speech coder, comprising:
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at least one predictive coding mode;
at least one less-predictive coding mode; and
a processor coupled to the at least one predictive coding mode and to the at least one less-predictive coding mode, the processor being configured to cause successive speech frames to be coded by selected coding modes in accordance with at least one pattern, the at least one pattern including at least one speech frame coded with a less-predictive coding mode. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of coding speech frames, comprising the steps of:
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coding a predefined number of successive speech frames with a predictive coding mode;
coding at least one speech frame with a less-predictive coding mode after performing the step of coding a predefined number of successive speech frames with a predictive coding mode; and
repeating the two coding steps in order to generate a plurality of speech frames coded in accordance with a pattern. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A speech coder, comprising:
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means for coding a predefined number of successive speech frames with a predictive coding mode;
means for coding at least one speech frame with a less-predictive coding mode after the predefined number of successive speech frames have been coded with the predictive coding mode; and
means for generating a plurality of speech frames coded in accordance with a pattern of speech frames encoded with a predictive coding mode and speech frames encoded with a less-predictive mode. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27)
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- 28. A method of coding speech frames, comprising the step of coding a plurality of speech frames in a pattern, the pattern including at least one predictively coded speech frame and at least one less-predictively coded speech frame.
- 31. A method of coding speech frames, comprising the step of coding a plurality of speech frames in a pattern, the pattern including at least one heavily predictive coded speech frame and at least one mildly predictive coded speech frame.
Specification