[vlc-devel] [bmpx] Proposal for a common D-Bus interface for media players

Milosz Derezynski internalerror at gmail.com
Tue Dec 5 19:02:43 CET 2006

---------- Forwarded message ----------
From: Milosz Derezynski <internalerror at gmail.com>
Date: Dec 5, 2006 6:49 PM
Subject: Re: [xine-devel] Proposal for a common D-Bus interface for media
To: "Brian J. Tarricone" <bjt23 at cornell.edu>

Chapter 1:

A "decent", "specific" real world usage of at least another point that Rafel
missed out to point out in this spec, is that there would be a single DBus
name (for activation) for all media players, org.freedesktop.MediaPlayer,
and this goes hand in hand with Portland Summit and xdg-utils.

I don't really think that e.g. ISVs want to care what media player is
actually the currently preferred one by the user, nor do they want to
"search" the system for a working one (think app searching for mozilla, then
firefox, then opera, then konqueror then, what else is there, to display
some HTML help page), and _nor_ should they (even if they don't care what
media player is the preferred one) override the user's setting.

We discussed this already (Rafael and me), how a system that provides only a
single DBus iface name can point to multiple apps, and my proposal turned
out to be a system made of one base service (i called it "pspd", for
Preferred Settings Proxy Daemon", it does not have to run constantly
though), and one for each desktop, which the desktops could provide ( e.g.
pspd-kde, pspd-gnome), in a similar way that hald-* and hald-addons-*
daemons work.

The base pspd would proxy the interfaces, and propagate the actual
activation to the specific pspd running for the specific desktop (they could
have iface names like " org.freedesktop.kde.pspd" or so). Saying that, the
base pspd and the desktop-specific pspd could be just as well 1 app/serivce,
and having said _that_, there is no real need for it to be desktop-specific,
but rather the desktops could store their settings using this common system.

There will be inevitably some cross-desktop system to start up the user's
preferred application when something asks for  "media player", and if you
want it or not i'm pretty sure this will work over DBus using activation and
a unified service name and the evil XML and whatever else.

(As for XML: Yeah sure you can overdo it but for rather small hierarchically
structure documents it's just right. I'd agree to say that GConf is
nonsense, but for certain specs XML is just ok)

Chapter 2:

Yeah i can already hear you all scream about "Lolz! Even more daemons! And
the network! And the RAM! The nuclear fallout! The human race!", well scream
as much as you want but please don't troll since we're in a discussion here
and if all you want to do is to block it, stop it, kill it down at the
beginning, then please step out of the way and let the people speak who want
to actually do something with it.

Like Rafael said, and he was very right to say it like this (because all he
wanted to know is whether he should keep you CC'd on this issue): "However,
if D-Bus is something you're interested in but don't have time to work on,
please let me know with a quick message."

It was too polite in fact, so i'm restating it as "If you're not interested,
just tell us we shouldn't mail you anymore but then leave us doing this job

There were already 2 other attempts to keep media players unified where it
makes sense: A common metadata database (which is arguably very much harder
to do right if possible at all), and one thing that goes just hand in hand
with what most people stated here: a common storage for album covers (again,
for those people who think album covers are useless and an obsession: Just
leave it, we don't want to know).

The latter discussion was effectively killed off by some people like you 1
year ago on the gnome-multimedia mailing list. So if all you have to say is
"We think it's stupid", then you're not the people want to talk to, and just
so we don't harass you in the future tell us to keep you not posted ,and
that's all, thanks.


On 12/5/06, Brian J. Tarricone <bjt23 at cornell.edu> wrote:
> Hash: RIPEMD160
> Mike Melanson wrote:
> > Allow me to inaugurate the flame war...
> >
> > Rafaël Carré wrote:
> >> That would let developers use this interface in their programs, and
> >> let their users decide of which media player they wanna use. All
> >> about FREEDOM.
> >
> > I read this as: "Real problems are too hard to solve. Let's create
> > different problems and solve those instead!"
> >
> > :)
> That's somewhat similar to my reaction.  I can see a need for a
> desktop/player-neutral audio API for things like sound notifications on
> certain events, but I don't see why individual media players need to
> have the same interface.  Users can already choose to use whatever they
> want.  If I'm just an application that wants to launch the user's
> preferred audio player (for example), there are already established ways
> of doing that that don't even require D-Bus.
> Embedding audio/video widgets in applications might be an interesting
> use for this.  However, this bit is way more complicated than just
> defining a common control interface, and varying feature-sets among
> different players makes it hard to have real drop-in replacements.
> Really, the only common use-case I can see here is the one mentioned in
> the original post: writing a little remote control GUI for Kicker, or
> gnome-panel, or xfce4-panel or whatever, and being able to have it
> control any media player that supports The Interface.  For such a
> limited use case, what's the point?
> I'm not trying to say this is a stupid idea,  I'm just saying I don't
> understand how it would be used by users and/or application developers.
> Come up with a decent list of *specific* potential real-world users of
> this interface, and then we have a purpose.
>         -brian
> P.S.  Maybe this should be moved to something like xdg at freedesktop.org?
> I know I'm only subscribed to one of the lists on this cross-post, and
> I have no idea if any of the other three will even go through.
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