How to play a tone sequence

To play a tone sequence defined in a descriptor do the following:

• Constructing and initializing

• Configuring

• Playing

Use the CMMFDevSound::NewL() method to construct a new instance of DevSound.

After construction, use an CMMFDevSound::InitializeL() method to initialize DevSound to play tones. This method requires that you specify the DevSound observer class to handle callbacks.

Once initialization has completed, successfully or otherwise, DevSound calls the MDevSoundObserver::InitializeComplete() function.

The following settings can be configured before or during tone play:

• To change the volume of the audio device to a specific value, use the CMMFDevSound::SetVolume() function. The volume can be set to any value from 0 to CMMFDevSound::MaxVolume().

  To define a period over which the volume rises from 0 to the normal volume level, use the CMMFDevSound::SetVolumeRamp() function.

  Note: The CMMFDevSound::SetVolumeRamp() function is only available during tone play.

• To set the speaker balance, use the CMMFDevSound::SetPlayBalanceL() function. This function has two parameters:

  • aLeftPercentage - the left speaker volume percentage.

  • aRightPercentage - the right speaker volume percentage.

• To set the priority setting for this instance of DevSound to access the audio device, use the CMMFDevSound::SetPrioritySettings() method. Priority settings are used by the Audio Policy component to resolve multiple requests to access the audio hardware.

To start playing a tone sequence, use the CMMFDevSound::PlayToneSequenceL() method:

IMPORT_C void PlayToneSequenceL(const TDesC8 &aData);

This method has one parameter, &aData, the tone sequence that is to be played.

When an attempt to play a tone sequence has completed, successfully or otherwise, DevSound calls the MDevSoundObserver::ToneFinished() function. If a tone sequence is not valid, MDevSoundObserver::ToneFinished() returns with an error of KErrCorrupt.

Note: Further calls to CMMFDevSound::PlayToneSequenceL() can be made both before and after the MDevSoundObserver::ToneFinished() callback is received.