[Openchrome-users] TV Resolution problems

Thu Apr 6 13:19:12 PDT 2006

On 06.04.2006 01:00:40 -0600, Chad wrote:
> On 4/5/06, Steffen Schumacher <steffen at schumacher.dk> wrote:
> > I'm wan't to build a MythTV box using a via M10000(CLE266) and a PVR-150.
> >
> > I seem to have several problems:
> > 1. CPU problems when decoding 720x576 mpeg2 ( unscientific top says ~ 100% cpu )
> 
> Decoding with what application using which output?  Mplayer using xv
> or mythtv using "standard","libmpeg2","Standard XvMC", "Via XvMC"?

using mythtv with setting Via XvMC.

> 
> > 2. Resolution - Using mode 720x576Noscale, the picture doesn't fit onto the screen?
> 
> Doesn't fit how?  Offset to one side, too big (zoomed?), too little
> (black box all around the image)?

Its too big. When I get some more time I'll try to tweak the mythtv config, so that
the screen fits. I'll then reconfigure the PVR-150 to output that same resolution to
avoid rescaling of the signal. Whatever works I guess.

> 
> > I've pulished xorg.conf and Xorg.0.log at http://131.164.191.12/xorg.conf and
> > http://131.164.191.12/Xorg.0.log
> > I'm running FC4 with a recent 'yum -y update', so I should have pretty much
> > updated stuff in there I think..
> >
> >
> > 1.
> > This is probably the most important. I think I should have enabled libVIAXvMC.
> > It should be enabled in mythtv and in xorg. (please look at xorg.conf and Xorg.0.log)
> > I'm missing some way to test if it is actually beeing utilized?
> 
> How is MythTV installed, via the source from mythtv.org or via RPM's
> from somewhere like Axel's Repo (ATRpms)?  If it's via the source, you
> should be able to duplicate the configure step to see if the
> libviaXvMC was found or something else.  If you are so inclined and
> lucky, you will see libXvMCW which is the wrapper script, in which
> case means you simply have to place the name of your via XvMC lib in a
> file.  So, if your XvMC lib (located in /usr/lib) is something like
> libviaXvMC.so.1 then you would:
> echo libviaXvMC.so.1 >> /etc/X11/XvMCConfig

Ok, everything is installed from atrpms using yum. After install I've updated
a few times also.
Ive added the libviaXvMC.so.1 to XvMCConfig also, but that doesn't change.

> And then start up mythtv, go to your playback setting, change the
> output to ViaXvMC (or even regular XvMC) and then try to watch an
> mpeg2 file.  See what the output in your mythfrontend log says (start
> it from an xterm so you can get instant feedback by switching focus to
> your xterm while the mpeg2 is playing back).
> 
> > All I'm seeing in Xorg.0.log is (II) VIA(0): [XvMC] Initialized XvMC extension.
> 
> That's good news.
> 
> > Should I do something other then simply enabling it in mythtv?
> 
> Well, maybe.  Depends on your configure step above as mentioned. 
> Should you want to hard code (I'm a fan of the wrapper library
> personally) the library, you could force mythtv you use your via XvMC
> library instead of the XvMC Wrapper.  If the configure script doesn't
> attach directly to your lib, you can edit the configure options that
> were created from the configure script to hard code the path of the
> XvMC library, though I don't recommend it.
> 
> > how can I test it?
> 
> If it's the wrapper, but starting mythtv, changing your output,
> watching a show and reading your xterm's output.
> 
I've tried that but I can't seem to hit any luck with that.
I've posted the output from xterm in http://131.164.191.12/front.txt
But it doesn't say anything about XvMC in there..

> > 2.
> > I think mythtv supports scaling the signal to a given size, so if i'm screwed,
> > I'll probably fall back to tweaking mythtv to only output to the visible parts
> > of the screen. However I've gotten the impression that scaling yeilds bad performance
> > and / or quality.
> 
> Not sure how you'd be screwed, but yes, MythTV does allow you to set
> the desired output size for TV playback versus GUI size.  Check in
> your Settings under Appearance, you will see seperate size for GUI and
> TV, adjust those numbers to your hearts content.  My understanding is
> that scaling is done by your CPU, so it will eat CPU cycles if you
> aren't outputting at the same resolution as the original content was
> recorded at; I think it's not as CPU intensive as one would think, but
> defintely chews a few.  Quality is probably close if not the same as
> long as you aren't scaling too much bigger than the recorded
> resolution (and your CPU isn't taxed).  If you are down scaling then
> you'll probably get at least as good of an image as the original
> recording (assuming it was done in mpeg2 and not in analog compressed
> to mpeg2).
> 
> > So I would like to be able to make all pixels visible on my screen to avoid this,
> > but I don't really know where to start?
> > If I use 640x480 resolution, it fits neatly.
> 
> Are you sure your source material has a 720x576 resolution?  I usually
> run mplayer to check that my resolution is what I think it is.  If
> 640x480 fits the best, you probably have source material at that
> resolution or close to it.  If you are sure it's 720x576, make sure
> Myth isn't scaling it down before outputting to your TV or Monitor.
> 
> > I'll post the output of xdpyinfo and xvinfo to respectively:
> > http://131.164.191.12/xdpyinfo &
> > http://131.164.191.12/xvinfo
> >
> > in about 3-4 hours (when I get home to the box ;o) )
> >
> > Please ask me anything you need.
> >
> > /Steffen
> >
> > _______________________________________________
> 
> The only thing I can think of that hasn't been posted would be your
> configure output from MythTV.  The only other thing I can think of is
> to tell us what you are driving (what is your display device), it
> might help us to suggest a resolution.
> 

This configure you keep speaking of.. is that also relevant if I didn't
build mythtv from src? I cant 'locate' configure anywhere..

/Steffen

Ps. got the res figured out: 672x544 with the output moved (14,8) pix.

> HTH
> 
> Chad