| 摘要 |
A "multi-stage" method of estimating pitch in a speech encoder (FIG. 2). In a first stage of the method, a set of candidate pitch values is selected, such as by using a cost function that operates on said speech signal (steps 21-23). In a second stage of the method, a best candidate is selected. Specifically, in the second stage, pitch values calculated from previous speech segments are used to calculate an average pitch value (step 25). Then, depending on whether the average pitch value is short or long, one of two different analysis-by-synthesis (ABS) processes is then repeated for each candidate, such that for each iteration, a synthesized signal is derived from that pitch candidate and compared to a reference signal to provide an error value. A time domain ABS process is used if the average pitch is short (step 27), whereas a frequency domain ABS process is used if the average pitch is long (step 28). After the ABS process provides an error for each pitch candidate, the pitch candidate having the smallest error is deemed to be the best candidate.
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