How to play a tone

To play a tone 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 set the number of times a tone is to be repeated during playback use the CMMFDevSound::SetToneRepeats() method:

  IMPORT_C void SetToneRepeats(TInt aRepeatCount, const TTimeIntervalMicroSeconds
&aRepeatTrailingSilence);

  This method has two parameters:

  • aRepeatCount - the number of times the tone is to be repeated.

  • &aRepeatTrailingSilence - the interval of silence to be played after each tone.

• 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, use the CMMFDevSound::PlayToneL() method:

IMPORT_C void PlayToneL(TInt aFrequency, const TTimeIntervalMicroSeconds &aDuration);

This method has two parameters:

• aFrequency - the frequency at which the tone is to be played.

• &aDuration - the period over which the tone is to be played.

Tip: If you want to play two tones simultaneously, the CMMFDevSound::PlayDualToneL method can be called instead of CMMFDevSound::PlayToneL(). CMMFDevSound::PlayDualToneL has an extra parameter, aFrequencyTwo, to specify the frequency at which the second tone is to be played.

When an attempt to play a tone has completed, successfully or otherwise, DevSound calls the MDevSoundObserver::ToneFinished() function.

Note: Further calls to CMMFDevSound::PlayToneL() can be made both before and after the MDevSoundObserver::ToneFinished() callback is received. If subsequent calls are made to CMMFDevSound::PlayToneL(), only one MDevSoundObserver::ToneFinished() callback is received.