Here goes:
I've been running mythtv for about 2 years now, using a hauppauge wintv pci card. It works fine, but I've been wanting to upgrade it past a single tuner setup for a while. This has been my project since last month - and what a mega project it has become! I've spent more time on this than I have at work over the last month!

I bought new hardware, making sure that everything I bought was well supported. Hauppauge pvr500 and a pcHDTV5500. And I'm using nvidia graphics cards (one mx4000 and one 7600gs) because they have better than average linux support. And of course a new matx mobo and case. I am currently running both machines, trying to narrow down the cause of my problem.

With previous versions of mythtv I have always used xine for DVD playback (should point out that DVD is MPEG2) so I have never had to deal with mythtv's internal MPEG2 playback controls.

Of course, the pvr500 has two mpeg2 hardware encoders. Last night, while watching a basketball game with a friend, I noticed the video was slightly choppy, jittery, or jerky. Whatever your adjective, it's minor. It only happens for a split second, but it happens pretty much EVERY second. Once you notice it, you can't ignore it - and it drives me nuts. I didn't notice it while watching my regular TV programming (maybe due to latency in my monitor). But as soon as I watch something with lots of action, I see it.

At first I thought it was just my hardware MPEG2 encoding needed to have the bitrate bumped up. So I tried bumping both bitrates by 1k. Still see the choppyness.

On a hunch, I enabled the Internal player for DVD playback. WOW. Very prominent during action flicks (I tested it with Star Wars). Unwatchable. The crisper image of DVD makes it quite clear that the playback is screwy.

CPU utilization is almost always below 30% from what I've seen: mythfrontend runs at 15-20%, ivtv-enc takes 1-4% and xorg takes 1-4%. I don't think it's a driver issue. Like I said, xine plays smoothly. I think it's strickly a mythtv config issue.

So I tested the various MPEG2 decoders. I can't notice any difference between either the Standard or the libmpeg2 decoders. Standard XvMC has another set of problems on top of the choppy playback: I get the greyscale OSD mentioned here at the MythTV wiki. Funny thing is, I get this greyscale OSD problem with both nvidia cards. Following the directions on that page, I fixed the greyscale with the mx4000 card. The playback doesn't seen any less choppy though, and now my DVD menu OSD is messed up because of the changes. I'm not too concerned about that though - I can always re-install. (Not like I haven't done it 50 times already in the last month - every time I get things working jjust a little better before I screw something else up)

Next I located this blog dealing with xorg.conf options for the nvidia drivers. This met with mixed success: playback was smoother, but I was getting video artfacts (squares of video stay on the screen for a moment) and other strange behaviours (Video skips a split second every once in a while.) The first few seconds after I tuned into a channel I would get really messed up playback. then things would get better.

I'm running out of leads. Does anyone have any ideas for me?

-Mike

_________________
-Mike
* Currently using 5E50, started with 5A16
* Soltek 75FRN2 with Athlon 2500, 1GB RAM
* Hauppauge WinTV PCI
* pcHDTV 5500

Update:
There are a few entries in the changelog for MythTV 20.1 (or more accurately, the release-0-20-fixes wich will be going into myth 20.1) which look like they reference my problem:

MythTV
Fixed V4L2 API compatibility with IVTV 0.8

MythDVD
Fixed choppy playback on some DVD main titles

Now I shift gears and try to compile mythtv from source.

-Mike

_________________
-Mike
* Currently using 5E50, started with 5A16
* Soltek 75FRN2 with Athlon 2500, 1GB RAM
* Hauppauge WinTV PCI
* pcHDTV 5500

R5E50 is pretty current. To see the max included MythtTV changelist number, from the main menu go to either KnoppMyth -> Version where it is the last line "software version" displayed or to Information Center -> System Status -> Listings Status where it's the last item on the first line. Then compare that to the changelist numbers here: http://svn.mythtv.org/trac/log/branches/release-0-20-fixes Any change list # higher than the one listed in the GUI isn't included.

Basically there have only been a handful of fixes since the version used in R5E50 and I don't think any of them match the ones you're talking about.

Try disabling this option: It too causes the jitters with my MX4000.

Option "RenderAccel" "1"
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MERCEDES-BENZ C112 SPECIFICATIONS