Setting volume not working with Phonon

David Jarvie djarvie at
Wed Jul 22 13:39:32 BST 2009

I have some code to set the audio volume, and to unmute, using Phonon.
Neither function works - no matter what volume I set (I've tried between
0.1 and 1), it always plays at full volume. Unmuting simply does not work
either - I checked the status in KMix, where PCM remained muted, even
after calling setMuted(false). (My master channel doesn't have a mute
control in KMix.)

An extract from the relevant code is below. Any help on how to get these
functions to work would be much appreciated.

Phonon::MediaSource source(audioFile);
mAudioObject = new Phonon::MediaObject();
Phonon::AudioOutput* output = new Phonon::AudioOutput(
                                Phonon::NotificationCategory, mAudioObject);
if (mUnmute)

Note that I've used debug output to confirm the values being passed to
setVolume(). In case it's relevant, this code runs in its own thread.

David Jarvie.
KAlarm author & maintainer.

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