The OS/2 multimedia system provides a number of system-wide values that can be queried and set by applications. Because OS/2 multimedia applications such as Volume Control and Multimedia Setup allow users to set system values, it is recommended that applications only query the settings users have selected. The following table describes the system values that can be queried and set using mciQuerySysValue and mciSetSysValue.
┌────────────────────┬─────────────────────────────────────────────┐ │System Value │Description │ ├────────────────────┼─────────────────────────────────────────────┤ │MSV_CLOSEDCAPTION │Query or set the current state of a │ │ │captioning flag. │ │ │By querying the setting of this flag, an │ │ │application can determine whether to display │ │ │text along with audio, for example, for a │ │ │hearing-impaired user. │ ├────────────────────┼─────────────────────────────────────────────┤ │MSV_MASTERVOLUME │Query or set the current master audio level. │ │ │This value acts as a "multiplier" of the │ │ │individual volume levels of each device │ │ │context, allowing one application to control │ │ │the volume for a number of open devices or │ │ │elements. │ ├────────────────────┼─────────────────────────────────────────────┤ │MSV_HEADPHONES │Reserved for future use. │ ├────────────────────┼─────────────────────────────────────────────┤ │MSV_SPEAKERS │Reserved for future use. │ ├────────────────────┼─────────────────────────────────────────────┤ │MSV_WORKPATH │Query or set the directory for storing of │ │ │temporary files by the media driver. │ │ │This value can be used to point to, for │ │ │example, a directory on the hard disk that │ │ │holds waveform data from a recording │ │ │operation. │ ├────────────────────┼─────────────────────────────────────────────┤ │MSV_SYSQOSERRORFLAG │Query the Quality of Service (QOS) error │ │ │flag. │ │ │By querying this flag, an application can │ │ │determine an error occuring during band-width│ │ │reservation. │ ├────────────────────┼─────────────────────────────────────────────┤ │MSV_SYSQOSVALUE │Query or set the QOS specification value. │ │ │This system-wide Quality of Service (QOS) │ │ │specification value is used for band-width │ │ │reservation (for example, bytes per second) │ │ │over the network. │ └────────────────────┴─────────────────────────────────────────────┘
The following code fragment demonstrates how to obtain the multimedia work path.
CHAR szWorkpath[CCHMAXPATH] ; /* Work path for temporary files */
if ( mciQuerySysValue( MSV_WORKPATH, szWorkPath ) )
{
/* mciQuerySysValue was successful, szWorkPath now */
/* contains the multimedia workpath */
}