| 摘要 |
PURPOSE:To eliminate the need of an exclusive multiplying circuit for adjusting the sound volume and an analog circuit by varying the variation quantity of quantizing width at the time of decoding of digital data subjected to adaptive difference PCM encoding, against the variation quantity set at the time of encoding. CONSTITUTION:A selector 21 of a quantizing coefficient shifter 2 selects an output of an incrementer 22 for increasing amplitude information A from an ADPCM(adaptive difference pulse code modulation) code by '1' by a sound volume increase signal VU, and outputs it to a quantizing coefficient selector 6. This quantizing coefficient selector 6 selects a quantizing coefficient of a value being larger by one rank than a value shown by the amplitude information A from a quantizing coefficient table 5, and decodes ADPCM code data. In the same way an output of a decrementer 23 for decreasing the amplitude information A from an ADPCM code register by '1' is selected from a sound volume decrease signal VD, and outputted to the quantizing coefficient selector 6. The quantizing coefficient selector 6 selects a quantizing coefficient of a value being smaller by one rank than a value shown by the amplitude information A from the quantizing coefficient table 6. |
