Volume control apparatus and volume control program

1. A volume control apparatus comprising:

signal processing section for performing digital signal processing and a scaling process on an audio signal outputted from a sound source;

level adjusting section for amplifying or attenuating a level of the audio signal outputted from the signal processing section, by an amount of adjustment determined based on an instructed amount of change, and outputting the amplified or attenuated audio signal to an outside;

storage section for storing a level value of the audio signal outputted to the outside and the amount of adjustment for the audio signal adjusted by the level adjusting section;

detecting section for detecting, when a volume controller is controlled by a user, time required for an amount of operation to reach a predetermined value;

first setting section for setting an amount of operational change based on the level value stored in the storage section and the detected time;

second setting section for setting an allowable amount of change by which the level adjusting section can make an adjustment by an attenuation process, based on the amount of adjustment stored in the storage section;

determining section for determining one of the amount of operational change and the allowable amount of change that has a smaller value to be the instructed amount of change; and

instructing section for instructing the level adjusting section to adjust the level of the audio signal based on the determined instructed amount of change.

2. The volume control apparatus according to claim 1 , wherein

when the level adjusting section is amplifying the level of the audio signal, the determining section further determines a predetermined amount of change to be the instructed amount of change.

3. The volume control apparatus according to claim 2 , wherein

the signal processing section further generates a plurality of channel audio signals based on the audio signal,

the level adjusting section further amplifies or attenuates levels of the respective channel audio signals,

the storage section further stores amounts of adjustment for the respective channel audio signals,

the second setting section determines allowable amounts of change for the respective channel audio signals, and

the determining section determines a smallest one of the amount of operational change and the allowable amounts of change for the respective channel audio signals, to be the instructed amount of change.

4. The volume control apparatus according to claim 3 , wherein

when the level adjusting section is amplifying at least one of the plurality of channel audio signals, the determining section further determines a predetermined amount of change to be the instructed amount of change.

5. The volume control apparatus according to claim 1 , wherein

the detecting section further determines, based on control performed on the volume controller by the user, whether an instruction to increase volume or to reduce volume has been received,

when the detecting section determines that the instruction to increase volume has been received, the second setting section sets the allowable amount of change, and

when the detecting section determines that the instruction to reduce volume has been received, and the level adjusting section is attenuating the level of the audio signal, the determining section further determines the amount of operational change to be the instructed amount of change.

6. A non-transitory computer-readable medium storing a volume control program that causes a computer in a volume control apparatus including signal processing section for performing digital signal processing and a scaling process on an audio signal outputted from a sound source; and level adjusting section for amplifying or attenuating a level of the audio signal inputted from the signal processing section, by an amount of adjustment determined based on an instructed amount of change, and outputting the amplified or attenuated audio signal to an outside, to perform the steps of:

storing a level value of the audio signal outputted to the outside and the amount of adjustment for the audio signal adjusted by the level adjusting section;

detecting, when a volume controller is controlled by a user, time required for an amount of operation to reach a predetermined value;

first setting an amount of operational change based on the stored level value and the detected time;

second setting an allowable amount of change by which the level adjusting section can make an adjustment by an attenuation process, based on the stored amount of adjustment;

determining one of the amount of operational change and the allowable amount of change that has a smaller value to be the instructed amount of change; and

instructing the level adjusting section to adjust the level of the audio signal based on the determined instructed amount of change.

7. The volume control program according to claim 6 , wherein

when the level adjusting section is amplifying the level of the audio signal, the determining step further determines a predetermined amount of change to be the instructed amount of change.

8. The volume control program according to claim 7 , wherein

the signal processing section further generates a plurality of channel audio signals based on the audio signal,

the level adjusting section further amplifies or attenuates levels of the respective channel audio signals,

the step of storing further stores amounts of adjustment for the respective channel audio signals,

the step of second setting determines allowable amounts of change for the respective channel audio signals, and

the step of determining determines a smallest one of the amount of operational change and the allowable amounts of change for the respective channel audio signals, to be the instructed amount of change.

9. The volume control program according to claim 8 , wherein

when the level adjusting section is amplifying at least one of the plurality of channel audio signals, the step of determining further determines a predetermined amount of change to be the instructed amount of change.

10. The volume control program according to claim 6 , wherein

the step of detecting further determines, based on control performed on the volume controller by the user, whether an instruction to increase volume or to reduce volume has been received,

when the step of detecting determines that the instruction to increase volume has been received, the step of second setting sets the allowable amount of change, and

when the step of detecting determines that the instruction to reduce volume has been received, and the level adjusting section is attenuating the level of the audio signal, the step of determining further determines the amount of operational change to be the instructed amount of change.