Re: [Ekiga-devel-list] preliminary patch for X-Video support

[Julien PUYDT <jpuydt free fr>]

Damien Sandras a écrit :
> Hi Matthias,
>
> Le mardi 12 septembre 2006 à 20:33 +0200, Matthias Schneider a écrit :
> > > Is XV support intended to replace GDK or SDL?
> > > I would replace both if possible.
> > Ok, on compile time we have options: configured with --disable-xv and without.
> > If disable-xv is given to configure, the behaviour is like before, GDK for window mode and SDL (if
> > found and enabled) for fullscreen mode. On linux systems only (to answer Juliens question),
> > without the --disable-xv given, ekiga will make use of the XV code for window (fully scalable) and
> > fullscreen mode. 
>
> Perfect. --enable-xv should be the default, but does xv work everywhere
> on Linux?

We must care also about *BSD, and we do have friendly @sun people whom 
we wouldn't want to make flee :-)

> > > I don't understand the problem.
> > >
> > > Can you elaborate on the functions flow and what is the exact problem?
> > Ok I will try to describe the problem in a better way. Right now the implementation works like
> > this: either we enable GDK/SDL OR XV output at compile time. However even if XV is compiled into
> > ekiga, at runtime it is possible that:
> > - there is no support for XV by the graphics driver
> > - there is no free XV port available because another program is using it.
> > Right now in that case there simply is no window.  I suppose it would be nicer to have a fallback
> > to the GDK/SDL implementation. The problem I am facing right now that I do not know whether XV is
> > available until the first frame is to be displayed.
>
> Ah, I understand!
>
> > Right now the output device is set in manager.cpp GMMAnager::GMManager() statically to GDK/SDL or
> > XV (via the device variable in OpalManager)
> > I this correct? I have not yet fully understood how the different output device are handled in
> > ekiga/opal.
>
> That is correct. Notice also that SDL support is a part of the virtual
> GDK device we implement and not a new PVideoOutputDevice.

This discussion makes me think about these enhancement bug reports I 
wrote some time ago :
http://bugzilla.gnome.org/show_bug.cgi?id=339883
http://bugzilla.gnome.org/show_bug.cgi?id=339881

because after all, what you want is being able to fall back on something 
else during the call...

> > My question now is where and how could I possibly implement a fallback in case XV is not
> > available? Can I register a PVideoOutputDevice_GDK from inside the PVideoOutputDevice_XV class? Or
> > where could I start to implement something like that? 
>
> I think that unfortunately you not switch from one PVideoOutputDevice to
> another once it is open. Doing so would require changes in OPAL.

See my bug reports : don't switch the PVideoOutputDevice, keep the same 
one, but put something else behind.

> Perhaps Craig can comment on this?
>
> So I see two solutions :
> - Modify OPAL so that you can change from one PVideoOutputDevice to
> another during a call
> - Create a new PVideoOutputDevice_Ekiga class from the current GDK one
> that is able to draw using xv and fallback to SDL or GDK if it is not
> possible.

Implement my idea.
Make your XV backend ask ekiga to use SDL when it has a problem.
Make the SDL one ask ekiga to use GDK when it has a problem.

> > Another idea would be to check once before registering the ouput device in GMManager::GMManager()
> > if XV is available and register the respective output device. This however would not cover the
> > situation that XV is available on a system, but no more ports are available.

My solution handles that.

> > I dont know if I make more sense than in my message from yesterday, perhaps it would be better to
> > use some code to demonstrateE?
>
> No, I understood the problem.

No, I understood the problem, and my solution will give other nice 
features :-)

> > > >   I also have an nearly similar DirectX class waiting for ekiga, hopefully I will find some
> > > time
> > > > soon. Please let me know what you think about this XV class,
> > > I like it :)
> > >
> > > Thanks!

I like the idea :-)

Snark