[mythtv-users] mpeg2 video stuttering

[Yeechang Lee]

ojw at weilerfamily.com <ojw at weilerfamily.com> says:
> The problem I'm having is that when I try to view either a recorded
> show or something live'ish (from the ringbuffer),

MythTV hasn't used a ringbuffer for live TV in almost three
years. Live TV is essentially an automated recording rule's that's
created and deleted on the fly.

> I was thinking it might be the marginally supported PCTV HD Pro USB
> stick

I don't use that tuner myself, but ATSC or QAM recordings are
all-digital and so either are stored to disk or they aren't; nothing
in the middle. It's not like a video card with inadequately-written
drivers that results in varying video performance.

Speaking of video cards . . .

> the view jitters.  What should be obviously smooth scene pans turns
> into jerky stutter steps through the scene.

Given that you specifically refer to pans I presume you get smooth
playback elsewhere, so it's not a driver issue that switching to the
proprietary Nvidia ones from the free Xorg ones would solve. As you've
already noted in your reply to Mike Dean, what you have isn't a
prebuffering-delay issue (although the Wiki page he pointed to, which
I hadn't seen, is great for those with that problem).

Does
<URL:http://www.gossamer-threads.com/lists/mythtv/users/203862#203862>
help? (Written more than two years ago so adjust driver version
numbers and some of the playback-settings wording accordingly. I'd
also try Standard decoder first.)

> I also tried playing the resulting mpegs in mplayer on the
> mythtv box.  At first, mplayer told me I didn't have enough
> CPU power to play the file

mplayer is great for what it does, but is irrelevant when discussing
how MythTV's internal player works.

mplayer's performance-related error messages are very generic and will
pop up in any context involving inadequate performance, whether
CPU-related or not.

> so I used the -ao null option to negate sound.  After I did that,
> mplayer didn't complain but it stuttered more than during playback
> in mythtv.

Likely the same cause that you're seeing in the MythTV internal
player, plus the by-default lack of deinterlacing.

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