[mythtv-users] Pvr350 TV-OUT decoder

jose rubio debian at nc.rr.com
Sat Feb 28 07:26:07 EST 2004


On Fri, 2004-02-27 at 14:37, Benjamin James VanderSluis wrote:
> Hey everybody,
> I am having a little bit of trouble with tv-out on the hauppage pvr-350.
> 
> Here's what I am using.
> KnoppMyth R4v2:
>   ivtv 0.1.9
>   MythTV 0.14
> 
> 
> I followed the HOWTO and am successfully running X on the television. When
> not using the Hauppage decoder TV comes up fine, but is, as expected, slow
> and jerky. When the "Use pvr-350's tv-out/mpeg decoder" box is checked, the
> screen simply goes black. From all I can tell via ssh, everything appears to
> be working fine. Just no picture.
> 
> I am able to send things directly to the tv via the command line with something
> like dd or cat, as described in the HOWTO.
> 
> So my questions are:
> 
>         1) How does Myth handle video?  Is the X-video stream totally
>            independent of the TV-video stream?

tv-video gets sent to /dev/video16 (I'm assuming you only have one card,
if you have morethan one the 16 might change to something else) and the
X display gets sent to the framebuffer device /dev/fb?
When you say like you said at the begining that video is jerky and slow
is because you are using /dev/fb? to display tv.  like you said, this is
bypassing the decoder so you will see a big change in your cpu usage.
(OT: the folks over at ivtv are playing around with all this and I hear
that a lot of this might change in the 0.2.0 version of the driver)


> 
>         2) What exactly does checking the "Use pvr-350's tv-out/mpeg decoder"
>            box do?

Simply to use /dev/video16 for display and not what is setup in your
XF86Config file (ie do not use the device that X is using)
Of course (and this relates to the next question) both /dev/fb0 and
/dev/video16 are going to display on your tv screen!!! dev/fb0 will
display X (and myth's EPG and myth's menu) and /dev/video16 will display
tv-out. so, how do you watch tv???  Well you have to turn the /dev/fb0
display off.  Myth does this automagically but if not using myth you can
do it with the "golbalalpha localalpha command from the ivtv driver
howto" which basicall turns off the /dev/fb0 display.  just a note that
it's not just an on/off command but it can take a value from 0-255. 
Myth takes advantage of this to provide semi-transparent menus (there's
a setting in myth that you can use to control how transparent the menus
will be)


> 
>         3) Could I send the TV-video to a TV-display and send the X-video
>            to a computer-display?  Discussions of the pros and cons of this
>            would be welcome.
> 
That's about how my setup is right now.  I have a monitor sitting next
to my tv.  When not running mythfrontend both screens show an x-desktop
when the mouse runs out one side of the monitor it shows on the tv and
vice-versa.  screen :0.1 is the tv, so to run myth I just type:

export DISPLAY=:0.1 && mythfrontend

and there I have it.tv on the tv and x on the monitor...just the way it
was meant to be :-)
Warning:  if you take the focus away from myth by clicking somewhere on
the monitor weird things can happen unless you've setup appropriately
(which I haven't yet)


>         4) Most importantly ... Do you have any ideas that might help
>            me get X and TV (using the 350's decoder) working?  Everything
>            seems to be in place and the hardware works.  I just can't
>            "Watch TV" from Myth :-(

Well, I hate to put it this way but you've just missed a step along the
way...

One thing that might have happened is that you use that "globalalpha
command..." damnit i can't remember what it was and I'm not at my
machine.  Anyway, if you are getting a black screen _AND_ sound comes
out of the tv-speakers it is because your /dev/fb0 display (which turns
black when myth is going to display tv) is showing in front of your tv.

the solution is simple.  reboot. don't mess around with anything just
start mythfrontend and watch tv. myth will take care of setting
everything up on start up.



Hope this helped a bit.  If nothing works then re-start the howto... or
follow another.  there's a bunch out there.


-jose-
> 
> 
> 
> Here is the HOWTO I followed:
> http://ivtv.writeme.ch/tiki-print.php?page=TvOutHowto
> 
> Here is my XF86Config-4
> http://www.ourapartment.com/XF86Config-4
> 
> 
> Thanks,
> Ben VanderSluis
> ----
> 

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