| 摘要 |
An apparatus and a method for transmitting an audio signal are provided to preprocess the audio signal by an analysis-by-synthesis scheme and transmit the preprocessed audio signal. A preprocessing filter(310) converts an audio signal inputted by a frame unit into a frequency domain, multiplies respective frequency components by a filter gain value, converts the audio signal of the multiplied frequency domain into a time domain, and outputs the audio signal of the time domain. The first voice encoder and synthesizer(312) encodes the audio signal outputted from the preprocessing filter(310), and decodes and synthesizes the encoded audio signal. A subtracter calculates an error between the audio signal outputted from the first voice encoder and synthesizer(312) and the audio signal inputted to the preprocessing filter(310), and outputs an error signal. The second voice encoder(332) encodes the audio signal outputted from the preprocessing filter(310), and transmits the encoded audio signal. A filter gain and switch controller(316) calculates the filter gain value by using the error signal outputted from the subtracter(332) and the audio signal inputted to the preprocessing filter(310), and provides the calculated filter gain value to the preprocessing filter(310). When the filter gain value is the optimum value, the filter gain and switch controller(316) outputs an audio signal processed and outputted by the optimum filter gain value from the preprocessing filter(310) to the second voice encoder(332).
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