Lennart Poettering wrote:
> An abstraction layer's main purpose it to abstract differences of what
> is below, and as hence usually is a least common denominator of what is
> below, but certainly nothing that adds features. PA OTOH extends what
> is below, it adds features.
Phonon also adds features compared to the underlying GStreamer or xine-lib
library. In particular, it can be set up to send different types of sounds
to different outputs, kinda like PulseAudio (but it's implemented at a
different layer, and of course it only affects applications using Phonon).
There's also work ongoing (that branch by Colin Guthrie) on making
PulseAudio sinks show up as Phonon devices, and even reproducing the per-
sound-type preferences set in PulseAudio (so Phonon still matches them by
default, while showing the list of devices within Phonon as opposed to one
"PulseAudio" device). There too, this is a feature not offered by GStreamer
or xine-lib, but implemented by calling PulseAudio directly. See
for this work.