Hi,
This is my first post to mythtv-users. I built my mythtv box somtime
back in August. It took me about 2.5 weeks to set it up (grueling)
trying this or that distribution and many different driver
combinations. Now that mythtv is working 99% properly it is a pretty
amazing program. It's kind of shocking but this not only works better
than the equivalent windows solution (MCE2005), it works better with
less horsepower under the hood, and driver support for some of my
components is actually less buggy than under windows. Well that's
another post; the subject of my current discussion are just a couple of
minor problems here or there that I can't seem to solve by myself just
yet. In order to detail the problem, I'll provide a short history of
the evolution of the mythtv machine so that if anyone sees something
that might have been done to actually cause the problem, they might be
able to point it out. If you don't want to go through such boredom you
can skip to the last paragraph which describes the problem in detail.
Here's a little background info on my problem starting with my current
configuration:
hardware:
Motherboard: Gigabyte GA7VAX; chipset: VIA KT400; BIOS: F4
Graphics card: ATI 9600pro (sapphire brand)
Sound: onboard, realtek something or other, one of those onboard 6.1
channel numbers.
TV tuner: ATI TV wonder pro (uses connexant)
Remote: ATI remote Wonder
Processor: Athlon XP 1700+ Palomino core
Ethernet adaptor: Zonet 802.11g card (ralink 2500 chipset)
HD1: Maxtor 80GB 7200RPM ATA133, 2MB buffer (Diamond Max Plus 9) -
stores root filesystem and mythtv recordings.
HD2: Maxtor 80GB 5400RPM ATA133, 2MB buffer (Diamond Max Plus 9 or some
such) - stores mp3s and mame roms.
NEC 24xCDROM drive - used for nothing once OS has been installed.
Software configuration:
Distro: Ubuntu Hoary
Desktop: gnome 2.x - ubuntu hoary default
Display driver: ATI proprietary fglrx module, latest version, but only
software OpenGL using Mesa
Ethernet driver: ra2500 compiled as a module from latest release
Sound system driver: via82xx - ALSA, hoary default version
TV tuner driver: cx88xx module (connexant), hoary default version
Remote control: ati_remote module - hoary default version
Remote implementation: X input device with xmodmap to assign key controls
Mythtv version: 0.17 - the latest version in ubuntu universe repositories
Mythtv plugins version: see line above
Working mythtv plugins: Mythmusic, mythgame
Partially working mythtv plugins: Mythweather (never can download
satelite image), mythweb (can view and make bookmarks but cannot browse
any pages due to error "kdelib not meant to run with root priveledges"
forgot exact offending library but some such, unable to view mythweb
html pages due to php syntax errors). mythtnews (can view rss headers
but no browsing).
mysql: latest hoary repository version
apache: see line above
php4: see line above
Basically all supporting myth software is at ubuntu hoary latest
repository level
Special hdparm commands: hdparm -M128 /dev/hda; hdparm -M128 /dev/hdb;
hdparm -B120 /dev/hdb (puts second HD to standby after 5 minutes)
hdparm shows DMA on
Athcool version: latest ubuntu repository version. "sudo athcool on"
command issued upon startup
Recording quality: 480x480 RTJPEG quality170 MP3 48kHz quality3- 40%
processor utilization
LiveTV quality: 384x480 RTJPEG quality170 MP3 48kHz quality4- 40%
processor utilization
watching recording: 10-20% utilization
Recording+watching recording - 60-80% utilization
This machine is set to run as the backend and I use it for my frontend
as well
Brief history of the setup arriving at current above config:
Original configuration: Same as above except motherboard is replaced
with an EPoX mobo with viaKT266A chipset, sound is replaced with a Sound
Blaster Live Value
Distros tested: Mepis -compiled mythtv 0.18 from source along with all
dependancies. This was the most trouble in terms of getting it working,
but I did have a working mythtv box there. No mythplugins would compile
or install no matter what I tried., so I moved on to Mandrake 10.1.
This was the slowest of all the distros I tried, also could not get
sound working without unwatchably bad quality of no end to hissing and
popping, so moved on to Knoppmyth. Knoppmyth installed a working mythtv
distro, but with extremely low video quality (355x240) I still had 95%
processor utilization. Anything higher and I got prebuffering pauses or
whatever they are called. On to Ubuntu (easiest distro I have ever
installed). Mythtv worked using 0.17 which is in the ubuntu
repositories. Followed an online guide for mythtv under ubuntu
specifically and was up and running. Bad video tearing and intermittent
beeping noises during recording or playback. Moved TV tuner card from
last PCI slot to third; perfect video capture now and no beepng noises.
Installed mythplugins, able to access mythweb server from other machines
at first, then inexplicably have lost this functionality. Last
remaining problem with recording involves occasional popping noise with
sound, nothing I couldn't live with and I started regularly watching
recordings. Watching a recording while simultaneously recording a show
works perfectly. Perfectionism leads me to search for source of
intermittant popping. Replace old KT266A mobo with less old KT400 one,
long believed dead, once supported a windows machine, now resurrected by
linux somehow (I cannot explain it, it stopped booting about 1.5 years
ago and I even got a warranty repair which didn't help, it stayed in a
closet for 1.5 years and now not only boots reliably every time, but
runs linux, not M$). At this time install athcool and issue hdparm
command to quiet down main HD. Install new HD with music and games on
it. hdparm it to quiet it down too. The mobo switch was made due to
belief that older via mobo had problems giving soundcard adequate power
with agp slot in use. Popping noise is reduced even more and almost
nonexistant.... BUT still there from time to time! Next theory, ALSA
drivers for SBLive are bad. Remove SBLive and use onboard sound.
Bingo. Sound is absolutely perfect. This step could not have been
taken with previous kt266 mobo because the onboard sound was unusable on
it: insane clicking and popping with any sound that would emanate from
the line out. Mythtv box is now 100% usable with good remote support
and good sound with good video quality, and quiet hardware, running cool
due to athcool. Last nitpicks include the mythweb server not working,
mythweather not downloading radar map. Those are pretty minor admittedly.
Now, the last problem I have to solve before my mythtv machine is 100%
operational and better than a TiVo could be, with no problems whatsoever
after this:
If the the machine is recording a TV program and I want to watch a
recording simultaneously, the playback skips whenever I try to seek by
jumping _ahead_, fast forwarding, or by skipping commercials. Jumping
back does not cause this problem. Also, if the skipping occurs, and I
pause it for a few seconds, and then resume playback, the skipping will
stop until after my next forward seek. The skipping also ocurs if I am
already recording and select to watch a recording; the skipping starts
as soon as the playback starts, and the pause tricl works. Without
recording at the same time, seeking is flawless. Setting hdparm -M254
or -M0 does not help, nor does setting athcool off. So this must be
related to the HD directly or the mobo-HD insteraction. Tried an
experiment: go to program guide and select a show to record. Now go to
"watch recordings" and watch this recording while it is being recorded.
Skipping problems ocur, ok expected. Now, go to watch live TV, I should
see skipping, because it is doing the same as playing back a recording
while it is being recorded. *NO* skipping watching live TV! Why? Live
TV plays back perfectly. Does anyone know anything about this? Anyone
else using a KT400 and encounter this problem? Can I fix this problem
by increasing the read ahead using hdparm. Defualt for most drives
seems to be 4KB, maybe if I set it to like 64KB or even higher, the
playback will not skip because it is able to keep the data stream
unbroken due to increased read-ahead. Anyone got any suggestions about
what read-ahead to use or iedas about why it would or wouldn't work.
Thanks everyone who can help and thanks for holding out on this long
post. Mythtv is great and it can only get better at this point. A real
triumph for linux. Let's hear it for the analog hole.
Raphael
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