API change needed for controlling Audio priorities

Audio priorities for QAudioInput and QAudioOutput in Voice UI are needed. For example, if a user is listening music and receives a new SMS. Then the voice UI can inform user about the new SMS using speech synthesis. The music can be faded out before a synthesizer starts talking. On the other hand, if a ringing tone is playing, SMS notification cannot be given. This kind of behavior can defined by using audio priorities.

Both Meego and Symbian devices have audio priority handling system. Without priorities platform specific back-ends are needed for Voice UI API.

E.g. QSoundControl has already priority settings http://doc.trolltech.com/qtopia4.3/qsoundcontrol.html#setPriority. However, it could be better to use integer values as a priority instead of enumerations. This way, it is easier to add new priority values and use platform specific values as well.

Use Case

The client should be able to say what is its type. E.g. "I am a music player/telephony app/voice recorder/calendar alarm" etc.