Jerky playback

[Chris Jensen]

Hi,
I probably should've asked this right from the start: I've noticed some
people talking about the Xv on the list, is this just an abbreviation for
XVideo, or is it something seperate, because my Xfree setup is loading
XVideo:
(II) Loading extension XVideo
But there's no mention of anything called Xv in the startup.
Is this all I need or have I been stupid from the start and not even
installed the basic requirement.

Thanks
Chris Jensen

----- Original Message -----
From: Gildas Bazin <gbazin at netcourrier.com>
To: <vlc at videolan.org>
Sent: Friday, July 13, 2001 3:16 PM
Subject: Re: Jerky playback


> On Tuesday 10 July 2001 2:56 pm, Chris Jensen wrote:
> >
> > Do you mean hardware acceleration for decoding mpeg or displaying? I'm
> > certain it can for the later (although I have yet to get xvideo
working),
> > and I would assume the former also since using --overlay did improve
> > performance slightly.
> >
>
> VLC doesn't use hardware acceleration for mpeg decoding as everything is
done
> in software. Well, maybe you can argue that using the ac3 spdif output is
> equivalent to using hardware acceleration because the ac3 audio is then
not
> decoded by VLC but by your ampifier (becareful, you need an ac3 amplifier
> with an spdif input).
> But VLC can make use of hardware acceleration for the video output. For
> exemple, the Xvideo output plugin will use an YUV hardware overlay. That
> means the decoded MPEG pictures which are in YUV video format won't have
to
> be converted to RGB in software, this step is done directly by the
graphics
> card. And I think Xvideo can also use hardware rescaling with
interpolation.
> So you will gain a lot using Xvideo.
>
> Another thing: I looked at the code, and it seems to me that the --overlay
> option is not used anywhere (It must have been used in the past but is not
> anymore). Well it is referenced once in the SDL output plugin, but it
doesn't
> do anything.
> So --overlay shouldn't make any difference.
>
> > > On the other hand it looks like you are missing one vital other
library,
> > like
> > > svgalib (I use svgalib-1.4.1-13.i386.rpm) or another. I can't remember
> > exactly
> > > which libraries you need.
> >
> > I'd say this is definately the problem as I had no idea i had to install
it.
> > Will I need to recompile vlc or anything else to take advantage of
svgalib
> > once it's installed? (ie xfree, or the xvideo component?)
> > Where can I find out what other libraries I need (since I have probably
not
> > installed them).
>
> I really don't think you need svgalib. All you should need for the Xvideo
> output is XFree 4.x.x and its development packages (for the header files
and
> other things ...)
>
> Also, If the SDL output and the Xvideo output are segfaulting on your
> computer but the x11 output is working fine, that would be a proof in
favour
> of an Xvideo problem on your computer. Because, as you were guessing,
libSDL
> is not a low level display driver, its goal is just to provide a
consistent
> API to access the video display on several platforms (this is why vlc's
SDL
> output plugin is working on Linux, Beos, Windows ...). And therefore it
will
> try to use the best display driver available on your computer, which in
your
> case will be Xvideo.
> If you want to make sure that Xvideo is working on your computer, try to
find
> another app that can use it.
>
> You can also try to use GDB with vlc to trace this segfault ;-)
>
> --
> Gildas
>
>