| 摘要 |
PURPOSE: To execute a digital level control function while preventing the deterioration in sound quality by controlling the gain of sound volume data by control data generated based on digital volume data and level reduction at the time of controlling digital volume by a digital volume circuit. CONSTITUTION: The deterioration preventing circuit is constituted of a digital signal processing circuit 10, a digital level control circuit 20, 1st and 2nd control signal detection circuits 30, 50, 1st and 2nd digital/analog(D/A) converters 40, 60, 1st and 2nd gain control circuits 70, 80, and 1st and 2nd low pass filters 90, 100. At the time of controlling digital volume, the operation of digital audio data is executed, and after adding control based on level reduction quantity, the gain of the operated audio signal is controlled by the circuits 70, 80 in accordance with the state of a control word. Consequently the digital level control function can be attained while preventing the deterioration of sound volume. |
