Control an Acoustic Processing Extension (APX) module
    Note: This utility can only be used if you have QNX Acoustic Management Platform 3.0 installed. 
 
Syntax:
apx_ctl [options]
Options:
- -a
            apx
- The Acoustic Processing Extension (APX) module to start or issue a command to. You can specify
              apx in the following ways: 
              - [card_num:]dev_num — card number and
                device number. The default for both the card number and the device number is 0. 
- name — APX card name (e.g., pcmPreferredp,
                  pcmCxDyp). 
 
- -e
            chns:volume_chn0:...:volume_chnN
- Set volume of external amplifiers (outside of io-audio system).
- -t
            dataset
- Load the specified runtime acoustic processing dataset.
- -u
            user_volume
- Override the default user volume with the system output volume.
- -x
            id:channel[:data]
- Set or get data on an APX module for parameters of size int16_t. where:
              - id is the ID of the parameter
- 
                channel the acoustics channel the parameter is for
- data is the data for the parameter (when setting only)
 
Description:
 The apx_ctl utility controls an Acoustic Processing Extension (APX) module.
        If you specify just the -a option, apx_ctl starts the
        APX. 
See the
apx_ctl.c appendix
for the source for this utility in the Audio Developer's Guide.