Media Control

TAPI can request the execution of a limited set of media control operations on the call's media stream triggered by telephony events. Although the TAPI clients normally use the media function specifically defined for the media type, media control can yield a significant performance improvement for client/server implementations because simple "detect/control" sequences can be offloaded to the server. The operation TSPI_lineSetMediaControl allows TAPI to specify a list of tuples specifying a telephony event and the associated media-control action, and thus sets up a call's media stream for media control. The telephony events that can trigger media control activities are:

• Detection of a digit: TAPI provides a list of specific digits and the media control action each of them triggers.
• Detection of a media type: TAPI provides a list of media types and the media control actions a transition into the media type triggers.
• Detection of a specified tone: TAPI specifies a list of tones and the media control action each tone detection triggers.
• Detection of a call state: TAPI specifies a list of call states and the media control action each transition to the call state triggers.

Media control actions are defined generically for the different media types. Not all media streams can provide meaningful interpretations of the media control actions. Operations that may be possible are indicated in LINEMEDIACONTROL_ Constants.

The scope of media control is bounded by the lifetime of the call. Media control on a call ends as soon the call disconnects or goes idle. Only a single media control request can be outstanding on a call across all applications.