[mythtv-users] Fast CPU, DMA enabled on HD, Xv enabled, still getting pauses in Live TV

[Joe V]

Albert,

It's a good thing that I haven't started my new job
yet, or I'd be going into work pretty tired (it's 3AM
right now).  I've spent the night scouring the mailing
list archives on a hunch (I thought that I saw
something before).

You may not have the same situation as I do, but I
highly recommend that you check the cable signal
strength (assuming you are using analog cable as I
am).  Apparently PC TV tuner cards are more sensitive
than a regular TV, and artifacts in the signal or a
poor signal can cause extra CPU usage, and frames
being dropped (I found this out in talking to my
ex-roommate and on the mailing list).

To verify this, I hooked up a VCR (hey, it's all I
have with a coax input) to the Television input on my
capture card (Leadtek Winfast TV XP 2000 Deluxe).  I
set the capture resolution to 480x480, uncompressed
audio and watched a tape.  The picture was nice and
smooth (need to work on the color a bit, but monitor
colors differ from a TV), no noticable dropped frames,
and no "rebuffering" messages.  This lasted for a full
hour.  The only possible problem message that I saw
was "IOBOUND - blocking in ThreadFileWriter::Write()",
and there's mention of that in the archives, so I'll
be doing some more reading.

All of this was done with a stock Red Hat 9
installation, running GDM, going into KDE, which will
not be my final setup (I will not use gdm, and will
boot straight into twm or blackbox or something, as
well as killing services, etc.)  I was using the
default settings (RTJPEG).  The user CPU usage never
went above 15% (this includes both Mythfrontend and
Mythbackend), which I feel are excellent numbers for
my hardware setup.  Adding a second tuner will work
out quite well when I decide to do so later on.

So, looks like tomorrow I'm making a trip to Radio
Shack for a signal amplifier and some new coax cable
(well shielded).  From there, make sure that normal
cable works, and then play around with using MPEG4
possibly, getting the best picture I can.

-- Joe

--- Albert Santoni <GameGod at sympatico.ca> wrote:
> Joe,
> 
> For the record, I would like to note that I have the
> same problem.
> I previously had a P3-500mhz that would pop in
> LiveTV quite often (cpu
> wasn't fast enough.)
> I upgraded to an Athlon XP 2000+, and now I get the
> pop about once every ten
> minutes, just like you do.
> The only thing I didn't swap out was my hard drives
> and PSU.
> (I also think MythTV 0.11 helped it a bit...  I
> think just the audio
> stutters now...  I may be wrong.)
> 
> Sounds like we have the same problem.
> (I've tried all the things you did - DMA, etc.)
> 
> Please let me know if you find a fix, and I'll keep
> trying to help you
> troubleshoot.
> 
> Thanks,
> 
> Albert Santoni
> 
> 
> ----- Original Message -----
> From: "Joe V" <joevph at yahoo.com>
> To: "Discussion about mythtv"
> <mythtv-users at mythtv.org>
> Sent: Tuesday, August 19, 2003 1:01 PM
> Subject: Re: [mythtv-users] Fast CPU, DMA enabled on
> HD, Xv enabled,still
> getting pauses in Live TV
> 
> 
> > Albert,
> >
> > With this particular motherboard, I did not,
> however,
> > with the previous motherboard that I was using
> (same
> > Athlon XP 2400+, DDR266), I did leave the default
> > compilation options and still had the same
> problems.
> >
> > I will probably try with a different power supply
> and
> > hard drive (the only two components not swapped
> out)
> > and see what happens.
> >
> > Thanks,
> > Joe
> >
> > --- Albert Santoni <GameGod at sympatico.ca> wrote:
> > > Did you try compiling without -march=athlon-xp?
> > > Just leave it at the default (i586??)...
> > >
> > > Someone had a similar problem, and this was the
> > > case.
> > >
> > > ----- Original Message -----
> > > From: "Joe V" <joevph at yahoo.com>
> > > To: "Discussion about mythtv"
> > > <mythtv-users at mythtv.org>
> > > Sent: Tuesday, August 19, 2003 3:44 AM
> > > Subject: Re: [mythtv-users] Fast CPU, DMA
> enabled on
> > > HD, Xv enabled,still
> > > getting pauses in Live TV
> > >
> > >
> > > > Okay, now I'm starting to go nuts.  I've gone
> > > through
> > > > the mailing-list archive, and have tried all
> sorts
> > > of
> > > > things.  Changing DMA parameters, recompiling
> > > MythTV
> > > > with -march=xthlon-xp, trying "nice" on
> > > mythbackend,
> > > > and several other things.  And I'm still
> getting
> > > > skips, and with this hardware, I don't see how
> I
> > > could
> > > > be having problems.  All I want to do is run
> > > > mythbackend and mythfrontend on the same PC
> > > without
> > > > stuttering in the video/audio.
> > > >
> > > > Perhaps based on my hardware/software setup,
> > > somebody
> > > > can make some additional recommendations.
> > > >
> > > > Hardware:
> > > > - Albatron KX400-8X motherboard (brought the
> ECS
> > > board
> > > > back to Fry's, too many problems) - VIA KT400
> > > chipset
> > > > - Athlon XP 2400+ CPU (2GHz real speed, 266MHz
> > > FSB)
> > > > - 512MB RAM (DDR333) - the BIOS indicates that
> the
> > > RAM
> > > > is running at 133MHz * 2.5 (333MHz)
> > > > - Matrox G400 Dual-Head (hooked up to a
> monitor,
> > > so
> > > > using Xv)
> > > > - Western Digital Hard Drive UDMA 100
> > > > - Soundblaster Live! 5.1 (using in full-duplex
> > > mode
> > > > with kernel drivers)
> > > > - Leadtek Winfast TV 2000 XP (I put in
> gbuffers=8)
> > > > - Tulip clone Ethernet card (no onboard NIC)
> > > >
> > > > Software:
> > > > - Red Hat Linux 9
> > > > - Recompiled the kernel, Linux-2.4.21,
> included
> > > the
> > > > low-latency and preempt patch
> > > > (/proc/sys/kernel/lowlatency shows 1)
> > > > - Before compiling any software, I set CFLAGS
> and
> > > > CPPFLAGS to -march=athlon-xp
> > > > - MythTV 0.11
> > > > - Killed off as many of Red Hat's services as
> > > possible
> > > > - Using twm as the window manager.
> > > >
> > > > hdparm -Tt shows:
> > > > /dev/hda:
> > > >  Timing buffer-cache reads:   128 MB in  0.41
> > > seconds
> > > > =312.20 MB/sec
> > > >  Timing buffered disk reads:  64 MB in  1.42
> > > seconds =
> > > > 45.07 MB/sec
> > > >
> > > > I'm using ext3 filesystems for everything, two
> > > > partitions, one for root, one for /home. which
> is
> > > > where MythTV files are stores (using symlinks
> from
> > > > /mnt/store).  The ext3 filesystem is mounted
> with
> > > > noatime, and in grub.conf, I put in
> > > > rootflags=data=writeback.
> > > >
> > > > I'm not really stressing things out, I'm
> recording
> > > > RTJPEG at 480x480, MP3 quality 7.  Switching
> to
> > > MPEG4
> > > > (as suggested in a post in the mailing-list)
> > > didn't
> > > > help any.  I have plenty of CPU time (it never
> > > goes
> > > > higher than 50% user, never less than 30%
> idle.
> > > Not
> > > > using jitter control, not using experimental
> A/V
> > > sync,
> > > > just using the default options.
> > > >
> > > > The only thing that I can think might possibly
> > > causing
> > > > some problems is that I have only one hard
> drive
> > > for
> > > > everything.  Either that, or I do I need a
> real
> > > 2.4GHz
> > > > machine (i.e. Intel?)
> > > >
> > > > Please folks, any suggestions?  Any at all?
> > > >
> > > > -- Joe
> > > >
> > > > --- Joe V <joevph at yahoo.com> wrote:
> > > > > Brian,
> > > > >
> > > > > Well, it helps a bit...  I upgraded to bttv
> > > 0.7.107
> > > > > (and specigied gbuffers=10), put my hard
> drive
> > > and
> > > > > DVD-ROM on seperate cables (don't know if
> that
> > > will
> > > > > help much), as well as forcing 32-bit
> > > operations,
> > > > > and
> 
=== message truncated ===


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