what to do with phonon & why aren't you using it?

[Kevin Kofler]

Harald Sitter wrote:
> A bit of background perhaps: waaaay back when phonon was conceived as
> multimedia abstraction library to serve as multimedia pillar. While it
> is certainly abstract and a library I'm not so sure about the pillar
> aspect ;) In fact, phonon is barely even an abstraction since I only
> maintain the vlc backend and nobody else maintains any other backend.

Well, that might be one (though not the only) answer to your first question 
("Why don't you use phonon?"). The preferred backend in distributions has 
been GStreamer for years. (At some point, it was even the one preferred by 
upstream.) It is also what QtMultimedia uses by default. Why was VLC chosen 
as the one maintained backend for Phonon?

These days, the Phonon GStreamer backend can have obvious defects (visible 
in less than 5 minutes of testing, e.g., Dragon Player crashing on exit), 
and nobody is here to care. This in turn will lead developers to stop using 
the "buggy" Phonon.

> So, one has to wonder if it'd not make more sense to put the bit of
> energy that flows into phonon to instead go into qtvlc and not have to
> deal with the abstraction element at all. Indeed all these
> abstractions seem a bit silly because the multimedia libraries
> gstreamer and vlc are already abstractions... it's nesting dolls all
> the way down.

Ah, the famous "KDE Abstracted My Abstraction Layer" quote (which I see you 
even used as a presentation title in 2011). ;-)

This is a bit of a mess indeed. One issue is of course that some people 
prefer GStreamer and some VLC (and then there may in principle be: native 
Windows or MacOS backends, a backend using FFmpeg directly, etc.), so then 
you end up with another layer to pick one of those. Kinda an instance of:
https://xkcd.com/927/

The whole history of multimedia on Qt is a mess. Phonon was started when 
something like QtMultimedia simply did not exist. That had made it so 
interesting to the Qt project that they started to ship Phonon with Qt. 
Unfortunately, that cooperation never worked as well as intended (I remember 
subtle incompatibilities between "Qt Phonon" and "KDE Phonon", different 
default backends or even different backends altogether, issues initially 
getting the GStreamer backend from "Qt Phonon" to fully work with "KDE 
Phonon", and bootstrapping / build order issues) and abruptly ended when Qt 
decided to reinvent the wheel with QtMultimedia (first as a part of 
QtMobility, then standalone).

As a result, we now have two competing Qt multimedia frameworks that both 
suffer or suffered from a lack of maintainers. QtMultimedia was in a 
horrible state a few months ago (so much that I ended up suggesting on the 
Qt developer mailing list to just use Phonon, which, I was later told, made 
some powerful people at Qt really hate me ;-) ). It seems to be better now. 
But now we have Phonon falling into pieces, with only one backend being 
maintained at all.

I wish Qt and KDE could work together on *one* multimedia framework, with at 
least a working GStreamer backend. Though I am worried about the porting 
effort, since it would mean at least one of the two APIs will go away, maybe 
even both (in favor of a completely new one). But if you are going to 
revisit the Phonon API anyway, it may be worth considering to work with 
QtMultimedia instead.

I would rather have one working multimedia framework for Qt than two 
half-unmaintained ones.

        Kevin Kofler