| 摘要 |
<p>A code conversion device for converting a first code string based on a first method into a second code string based on a second method. An voice decoding circuit (1500) acquires information of a first linear prediction coefficient and an excitation signal from the first code string and drives a filter having the first linear prediction coefficient by an excitation signal obtained from the excitation signal information, thereby generating a first voice signal. A gain code generation circuit (1400) calculates a gain (optimal gain) at which the distance between a second voice signal generated by information obtained from the second code string and the first voice signal is minimum and corrects the optimal gain, so that gain information in the second code string is obtained according to the optimal gain which has been corrected (corrected optimal gain), the aforementioned optimal gain, and a gain read out from a gain codebook in the second method. Here, according to a voice judgment value, at a non-voice section, a gain is obtained by using an evaluation function which reduces the gain time fluctuation of the second code string.</p> |
