[mythtv-users] Help working out XvMC, de-interlacing, and a few other basics

[John Biundo]

Hi all,

I hope you can bear with me a bit and help me with a few basics.  I've 
been piggybacking on a couple of other recent threads, and googling my 
brains out, but I'm still at the stage where I don't know what I don't 
know, so I'm chasing my tail a little.  I thought I'd break down and 
start a new thread with a couple of my basic questions.

First basic question: How do I know if I'm using XvMC?  I've got an 
nVidia 5200 based video card.  My readings lead me to believe that this 
is not something that is "settable" in my xorg.conf or via 
nvidia-settings.  Is this something that must be enabled/disabled when 
mythfrontend is built?

Further clues:
- I *do* have a "Use libmpeg2 for decoding" choice in my mythtv General 
Playback settings page.  The help text says this setting is 
"unavailable" if using XvMC.  I normally take "unavailable" to mean that 
the choice is disabled (i.e., greyed out), but it's not -- I'm allowed 
to check the box.
- second clue: doing ldd /usr/bin/mythfrontend doesn't show any XvMC 
related libraries linked.

My tentative conclusion: I *think* this all means my mythfrontend 
(standard ubuntu distribution, 18.1) wasn't built with XvMC support, but 
I've had a helluva time trying to verify that fact.

Am I on the right track?  If so, is it worth trying to build mythtv 
myself to get XvMC?  Will it likely lead to improved quality (my main 
issues are with fast-moving scenes, like a football game)?  I've got a 
pretty powerful box with plenty of CPU, so that's not really a 
motivation for me.

A related question is: can you still select custom de-interlacing and 
filters when you DO have XvMC enabled?

Next basic question: If I'm displaying on a regular SD TV, is 
de-interlacing actually relevant?  From my (uninformed, newby) readings, 
I thought de-interlacing was for displaying on progressive scan devices, 
but lots of advice seems to suggest using de-interlacing even for 
regular SD TVs.  I'm confused.

Thanks for bearing with me!

Cheers,
john