[mythtv-users] How functional is Myth PIP ?

R. G. Newbury newbury at mandamus.org
Sun Jan 3 00:13:58 UTC 2010

Brent Bolin wrote:
> On Sat, Jan 2, 2010 at 1:15 PM, RAM <ram at bca.com> wrote:
>> On 01/01/2010 04:34 PM, Brent Bolin wrote:
>>> I would be more then happy to give you as much detail as possible.  It
>>> has just been my experience that I have better luck not using any of
>>> the VDPAU options within MythTV.
>>> I have three ZOTAC IONITX-A-U Atom N330 1.6GHz Dual-Core Mini ITX
>>> Intel Motherboard
>>> Believe the graphics card is GeForce 9400M
>>> Three different displays
>>> 1. Toshiba HD LCD 19LV505
>>> 2. Samsung HD LCD P2370
>>> 3. Panasonic PT-53WX53 HD rear projection
>>> I'm not sure about the interlaced specifications your talking about.
>>> I'm pretty new to much of this.
>>> Pretty sure the Samsung can do just about anything.
>>> When any of the VDPAU options are specified in Mythtv setup, playback
>>> appears to be stuttered or out of sync. Can't really look at the other
>>> displays because they are in use.  Think I was also seeing pause
>>> errors.
>>> CPU usage is less with VDPAU enabled.  When running in "High Quality"
>>> CPU usage bounces around 25% usage.  These boards show (4) cpus with
>>> `top`
>>> _______________________________________________
>>> mythtv-users mailing list
>>> mythtv-users at mythtv.org
>>> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>> Hi Brent,
>> 2 thoughts on why you may have the stuttering issues.
>>    1.    VDPAU lowers the the cpu usage so much that the cpu throttling does
>> not let the buss move data fast enough.
>>    2.    I have a couple of Intel based systems and the hyper-threading
>> (virtual cores) causes problems under certain conditions. They end up
>> starving for cpu cycles depending on what the main core is doing.  From
>> observation, it looks like Linux rotates the processes through the different
>> cores every few seconds either as a work around for this or more likely to
>> even out heat generation.  For MythTV I am using AMD processors, I have
>> tested on the Intel boxes, but never tried turning off hyper-threading in
>> the BIOS.
>> Roy
>> _______________________________________________
>> mythtv-users mailing list
>> mythtv-users at mythtv.org
>> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> What does using the different playback options do?
> The Nvidia GPU is capable of using acceleration etc...
> There are many options in the bios to be tweaked.  From setting static
> RAM to letting it use dynamic RAM.  To throttle or not throttle etc...
> Does Myth have different hooks(lack of better word) for native Nvidia driver?
> I'm not really complaining.  Using "High Quality" gives very good
> results.  With 1080 or 720

It sounds like you have not set up vdpau completely.
There are settings which can only be enabled in the nvidia driver 
through /etc/X11/xorg.conf.

In Setup ->Tv Settings -> Playback -> Page 1 there are a couple of 
settings which affect how how things work/look.
The important settings start on page 3. To understand the differences, 
you need to 'Add new' various playback profiles, naming each one to 
reflect the deinterlacing method.  Edit the resolution setting. For 
testing, you probably want >= 0 x 0, select Vdpau, set max cpus at 1 
(for testing), and uncheck OSD fade.
The de-interlacers are set on the 'Next' page. Select a Primary (and for 
testing, leave the Secondary blank. Leave any default 'Custom Filters' 
alone. For full results, you will have 7 different profiles: None, One 
Field,Bob,Advanced(1), Temporal(1), Advanced(2) and Temporal(2).

For testing, you want a high-quality high-def action clip. In North 
America, NFL or college football from one of the networks is your best 
bet. Manually record a clip, so that the action begins from the first 
second... no commercials!
Now play that clip using each profile. Maybe try ranking them, then test 
A versus B until you find the one you like best. Then test it, with some 
of the other settings changed: using 2 cpus. When you are happy, go back 
and do the whole thing again, with a digital standard definition clip. 
You might prefer a different deinterlacer.

If you really cannot see any difference between the various 
deinterlacers, you had best google how to do a tuneup on your LCD TV, 
because there are quite visible differences between/among the various 
interlacers when playing different content. My choice is Advanced(2) on 
my 9500GT although it will do Temporal(2), but that looks just slightly 
blurred to me, on fast moving objects (like a football!).

The 9400 chipset in the Zotac Ion will do Advanced(2). It did for me, at 
least. My 9300 chipset in my desktop doesn't really do Temporal(2).
The wiki has lots more about this.


         Please let me know if anything I say offends you.
          I may wish to offend you again in the future.

          Tux says: "Be regular. Eat cron flakes."

More information about the mythtv-users mailing list