request for phonon API addition

Kevin Krammer kevin.krammer at
Thu Nov 1 15:03:36 GMT 2007

On Thursday 01 November 2007, Matthias Kretz wrote:
> On Thursday 01 November 2007, Kevin Krammer wrote:
> > > Rationale: many apps that don't care for KDE don't care for the
> > > category (as it doesn't make much sense to them anyway).
> >
> > I afraid I don't get this part of the rationale.
> > As far as I understand Categories have nothing (directly) to do with KDE
> > but rather with user experience, e.g. automatically reduced notification
> > volume when media playback occurs.
> True. That's the theory. But without KDE there's currently no way to make
> those categories behave any different on Win and Mac. Meaning it makes 0
> difference whether your app uses CommunicationCategory or MusicCategory on
> Windows which has no equivalents for this.

"Added Value" for KDE then.
But since it does not likely make any difference for other platform, setting 
the correct category doesn't hurt either.

As the framework provider I'd strongly recommend to my users (the developers 
using it) to do this correctly (thinking about the category), because if such 
a distinction becomes available in a future release or update of the 
platform(s), they automatically benefit from it (added value for the 
application vendor)

> Perhaps Vista has something that comes closer to this, but so far I've not
> learned of anything in the Windows configuration that would influence
> Phonon at this point wrt categories.

Even if the platform itself does not have such a capability, the respective 
backend or associated tools might, e.g. as you write below, priorizing 
devices depending on category.

> > I assume the context of the above statement are Qt-using non-KDE
> > application, but, if I take Skype as an example, I'd still expect it to
> > use CommunicationCategory, especially since it's well known to be a Qt
> > application.
> Yes, Skype cares for KDE (in contrast to some in-house app that is confined
> to one platform) and for them it's easy to identify the category to use.

Speaking as a developer of a vertical application, where one of the deployment 
scenarios is just an Xserver and a customer specific window manager, I'd 
still would see a benefit in e.g. using NotificationCategory for if it allows 
me to mute/unmute my notification sounds probably with just changing a single 
line in a configuration file.

> > Since all the other values are "named", what about GenericCategory?
> app is categorized as Music, Video, Notification, ..., Generic
> or
> app is categorized as Music, Video, Not... or not categorized

Which category do you use as default right now? Or does it currently not have 
a default category?

> Actually I'm thinking of something like this:
> Backend defines initial preference of devices. This is used for all audio
> outputs.
> Phonon KCM can reorder the default preference of devices (not tied to any
> category - affects all audio outputs then).
> Phonon KCM can reorder the preference of devices per category. It then
> affects only the audio outputs for the given category.
> This would also solve the problem of having to reorder 6 lists of devices.
> Remaining problem is a good UI for it...

Sounds like a good strategy, however I have to admit that I do not understand 
all implications such a behavior might have.


Kevin Krammer, KDE developer, xdg-utils developer
KDE user support, developer mentoring
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