[mythtv-users] Switch FC3 to Kubuntu Feisty, now HD is very jerky

Brad Templeton brad+myth at templetons.com
Sun Jun 3 23:17:55 UTC 2007


I have been moving my systems to ubuntu (kubuntu) and am now working
on the systems running Myth.   (I have 6 linux boxes in my house,
don't you?)

So I upgraded my main frontend from ancient FC3 to Kubuntu Feisty.
That install was smooth and pleasant generally, and I recompiled
Myth from a recent SVN checkout.  I have the lastest nvidia
drivers installed by automatix2, as well as the many multimedia
players (xine, mplayer etc.) which work fine and can play HD.

However, Myth now produces very jerky video on HD.   The apparent
cause is video getting ahead of audio.   I became an expert on getting
Myth working on the old system, but none of the tricks are working here.

Log entries look like this:
    2007-06-03 15:08:41.441 NVP: Video is 14.5947 frames ahead of audio,
                        doubling video frame interval to slow down.
    2007-06-03 15:08:41.446 AO: Broadcasting free space avail
    2007-06-03 15:08:41.447 AO: audio waiting for space on soundcard: have 104 need 4096
    2007-06-03 15:08:41.458 AO: audio waiting for space on soundcard: have 2360 need 4096
    2007-06-03 15:08:41.470 AO: Broadcasting free space avail
    2007-06-03 15:08:41.471 AO: audio waiting for space on soundcard: have 612 need 4096
    2007-06-03 15:08:41.477 NVP: Video is 16.6105 frames ahead of audio,
                            doubling video frame interval to slow down.
    2007-06-03 15:08:41.482 AO: audio waiting for space on soundcard: have 2860 need 4096
    2007-06-03 15:08:41.494 AO: Broadcasting free space avail
    2007-06-03 15:08:41.495 AO: audio waiting for space on soundcard: have 1132 need 4096
    2007-06-03 15:08:41.506 AO: audio waiting for space on soundcard: have 3380 need 4096
    2007-06-03 15:08:41.509 NVP: Video is 17.8376 frames ahead of audio,

CPU is fine, running about 30-40% idle -- this is a 720p video on a
P4-3ghz, and never had any problems with 720p or 1080i before.  As noted
xine and mplayer are able to play the videos fine.

I tried various tweaks:
            OpenGL video sync on or off
            Extra audio buffering on or off
            Use video as timebase on or off
            Deinterlace on or off (should not matter on 720p)
            libmpeg2 decoder instead of ffmpeg (in spite of what it
                says, libmpeg2 seems to have better idle times so I
                am sticking with it even though it's a P4)
            realtime priority on or off



Other changes:
        I added some more memory.  It's PC2700 instead of PC3200 but
        this mobo handles that, clocking each bank independently.

        I recompiled Myth, removing restrictions on architecture
        that were there so I could move the binary to my Athlon.

        Video driver is of course new, card is still Nvidia 5200.
        Removed modelines (newer X now figures out the DPMS)

        Changes to UI size and overscan due to new X config. (odd,
            that this happened, but not hard to fix)

        I turned on NvAGP in xorg.conf as getting suspend working
            is one of my big goals.


Other issue:
        When the system boots up, or comes out of screensaver
        (which I thought I disabled) there is wiggling to elements
        on the screen for about 20 minutes that was not there before.


In all cases myth is still using oss /dev/dsp, should I switch it to something else?
It works OK on my desktop machine like this with the same settings, though
that machine is much faster (Core 2 DUO 6600, nvidia 7600)

Should I put an nvidia 7600 into the Myth machine?  It just generates
more heat, I don't need its extra abilities.

Any other thoughts?


More information about the mythtv-users mailing list