Hello

I've been using MythTV for couple of months now and really like it, although I have had some problems.

R5F27 worked quite well for me. Backend crashed every now and then, but export MALLOC_CHECK_=1 in /etc/profile fixed that. Frontend crashed every now and then but not too often. Setup was relatively painless although I had to change driver in xorg.conf from ati to radeon. I probably wouldn't even have upgraded to R5.5 but I wanted to get multirec. Now I'm wondering if something perhaps went wrong with upgrade or if R5.5 is just very unhappy with my hardware.

Worst problems are with mythtv-setup, which fortunately one doesn't need very often. About 10 % of the time it segfaults even before it gets the GUI up. Tuning channels for my three DVB tuners is a pain. Attempt to tune crashes setup something like 90 % of the time. If it actually gets started, it always goes all the way (even doing complete scan all transports tuning). Took me quite a while to get everything tuned, but since I only need to do it once, no problem.

Backend is quite stable, but still crashes every couple of days (export MALLOC_CHECK_=1 doesn't seem to help this time. Previously there was some error in logs, now it just stops). No worries, I set up a script to monitor and restart it if that happens. I can live with that although this probably isn't normal.

The frontend, on the other hand. Crashes every time after:

1. Watching live TV (never during watching)

2. Watching a recording and trying to go back from list of recordings (to media lirary screen)

I have both UI and playback set up to use OpenGL. If I use something else than OpenGL for playback, the crashes happen when stopping playback, but only something like 80 % of the time.

The CPU utilization is also quite high, especially with OGL renderer. Around 40 percent for SD and too high to play HD (crash after few seconds of choppy playback). This could have been to case with R5F27 already. I wasn't paying attension then. The 40 percent number is minimum. With some deinterlacers (yadif for example), playback becomes choppy and CPU is at 100 percent.

Playing around with other renderers (I don't remember if it was directfb or xv-blit) I got CPU utilization of 20 percent at the lowest, which seems a bit high.

Now, even the frontend isn't really a problem. I have script monitoring it too and since it never crashes when playing videos (the CPU is capable of anyway), crashing isn't really a huge problem.

My setup:

Opteron 180 (dual-core, 2.4 GHz, 2x1 MB cache)
Asus A8N SLI Deluxe (nForce 4)
3 GB of memory
Ati X800XL
3 Satelco Easywatch DVB-C PCI cards (SAA7146 (rev 01) in lspci)
Two Seagate hard drives (/myth/video/tv is on dedicated drive)

This is actually my old gaming rig and I know it is not ideal for MythTV from compatibility point of view.

What I would like to have your opinions on is:

1. Is there some known problem with my setup? I know the motherboard is crap (as seems to be nForce 4 in general) and that Radeons and Linux in general is asking for trouble. Is this a hopeless battle if I don't change graphics card/motherboard/processor/tuners?

If you think I should choose different hardware, what would you suggest? I really wouldn't want to toss away perfectly good dual core machine.

2. Do you think a clean install would help?

By clean I mean really clean, not just backup-reinstall-restore, which I have already done. If so, how could I do it without losing all my recordings? Is there an easy way to just restore recordings (or more precisely, the data about the recordings. The mpegs are, as stated, on another drive)?


So far, I have run memtest for a night and found no errors. Everything else seems to be working ok. The machine itselfs has never crashed, only Myth related stuff (of course, the machine isn't doing much more anyway).

I appreciate any input.

-JLarja

Wish I could answer some of your specific questions, but they're over my head. Do you have a spare HDD? If so, pull out current one that contains your "live" KM install and do a clean install on your spare drive to see if any of the backup files are some how causing your problems.

I always keep an old HDD handy for these sorts of experiments so I don't roach my functional KM install.

_________________
Retired KM user (R4 - R6.04); friend to LH users.

Re: playback performance problems. I didn't see anywhere in your post where you state which "playback profile" you are using or tried to use. There are some things in there (like deinterlacing options) which makes it sound like you were in those settings, but let us know what preset profiles you tried (CPU++, CPU--, slim, etc).

Also not listed: what kind of display are you using, what's its resolution, and how are you connected to it? Obviously if you're trying to do 1080p over HDMI that's quite different than using standard TV out via composite or S-video.

That's not a bad idea considering I actually have a spare hard drive (or more like four). I will probably try that tomorrow.



Ah, you always forget something...

I have used custom profile, since some of the presets had problems with OSD. I just tested couple different profiles (SD content):

slim: 12
CPU--: 40
High quality: 40

I'm not sure if high quality is what that last profile is called (I use Finnish translation). I accidentally destroyed CPU++ profile, but between CPU-- and High quality there doesn't seem to be any difference. Slim got CPU utilization down, but even with it trying to watch HD crashed after few seconds of choppy playback (CPU at 100 percent). Perhaps it would be possible to make slim use both cores, but HD isn't really a priority, since I don't yet have an HD capable TV.

By the way, turning on OpenGL vsync if using some other than OGL renderer causes weird playback issues: in few second intervals video is displayed at high speed and then nothing is displayed. Usually frontend crashes in about ten to fifteen seconds.



1024x768@50 Hz. I have an external VGA->PAL converter. I haven't been able to get TV-out working. I didn't even bother to ask about that. There are too many ati-tv-out-not-working threads all over the net.

I'll be posting tomorrow to let you know if making a clean install to another drive worked.

-JLarja

Well, I was bored and had some time before Mythbusters was scheduled for recording, so here goes.

I started by reinstalling R5.5. Installation went smoothly to the point, where I should have tuned the channels. Mythtv-setup crashed on the attempt. I went through the rest of the setup and returned to tuning. Some 5-10 crashes later, I had managed to tune channels for one of the cards, so I went to test frontend. The CPU load and crashes were there, just like before.

So, unfortunately, problem seems to be with R5.5. To make that certain, and to check out the CPU utilization*, I installed R5F27. After manually setting up X, everything went quite well. Mythtv-setup did crash after I had setup channels on two of the tuners, but otherwise there was no problem.

[*] I haven't stated this before (at least, not very clearly), but the utilization is that of mythfrontend process. X howers somewhere below 10 percent, mostly somewhere around 2 or 3, on both R5.5 and R5F27.

On R5F27 the CPU utilization was only around 7 to 10 percent. Deinterlace method was linear blend and MPEG2 decoder standard. With kernel deinterlace method, CPU utilization was up to 11 percent, so not much change there. There doesn't seem to be much difference between R5.5 and R5F27, if deinterlacing and rendering settings are the same. Unfortunately, R5F27 wasn't able to playback the HD recording I have, it just showed blue screen and crashed after a while.

So, any suggestions? I don't know if this really cleared things up even a bit, but at least I now know that reinstalling everything won't help. I would of course like to know if someone has a similar setup. I am most suspicious about the Radeon, but unfortunately, I don't have an Nvidia graphics card to test with. If I don't find any solution, I might go and pick a cheap one with passive cooling. Or perhaps I just wait for R6 .

Edit: Just for the fun of it, I tested R5.5 with 1920x1200 resolution. Effect on CPU load was just few percentages, too small really to notice without better testing.

-JLarja

From all the crashing going on, I'd suspect some sort of hardware problem or incompatibility. R5F27 and R5.5 shouldn't really be crashing, especially in the setup screens. I see you have 3 pci tuners. Maybe they aren't sharing interrupts correctly or, as you say, something with ATI card, or a combination of the two.

Since R5.5 crashes the easiest, try a virgin install on your spare hard drive with only one tuner in place. If that still crashes try the install again with the tuner in a different slot. If you can find a slot that works, then try adding a second tuner and see if that starts crashing. If you video card is in an AGP slot, try leaving the PCI slot next to it empty. Those two often share an interrupt on many motherboards.

If it keeps crashing, even with one tuner, I'd try to find a different video card to test. Even if it isn't nvidia and can't play back hd, it should be able to get through the setup screens without crashing. If a different video card doesn't crash during setup, then you can suspect the ATI more strongly as the culprit.

What I find weird is that R5.5 crashes so much more often. But now that you mentioned interrupts I remembered something.

Originally, when I was intalling the tuner cards, one of them wouldn't show up in dev/dvb. Lspci showed the card, but subsytem line was different from other two identical cards and interrupt was shown to be 255. The fix was also quite interesting. I had disabled all the unnecessary stuff from motherboard's BIOS (extra sata raid controller, serial ports and so on). Enabling everything helped and I haven't thought about this since then. I really should have remembered .



I will try R5.5 with one or two tuners. Radeon is in PCIe slot so I don't think that should cause problems with PCI devices, at least not because of interrupt sharing. The motherboard only has three PCI slots, so there shouldn't be traditional only-four-lanes-for-PCI sharing problem, but who knows.

I'm not really familiar with how current (APIC?) motherboards handle interrupts. Is there some way to check how the sharing is done?



I do have some old Matrox Millenniums for PCI, perhaps even one or two S3s...

-JLarja

After several reinstalls and card swappings I have very little news.

Taking the tuner cards out and changing the PCI slot of a single card didn't have any kind of effect. After I had established that, I tried to replace Radeon with Matrox Millennium (I or II, I'm not sure) PCI card. The motherboard apparently didn't like that. I managed to boot once, but not again (I actually had two of these cards, one with 8 other with 16 MBs of memory. Neither worked except for that one time).

With S3 Trio based PCI card I could boot and install R5.5, but couldn't get the X to display anything. Everything seemed to be ok, and X apparently though everything was fine, but all I could see was blank screen. So unfortunately, I couldn't eliminate the possibility that Radeon is incompatible with something in the system.

I did, however, play around with BIOS. By enabling and disabling different devices and flipping "Plug and play OS installed" parameter from yes to no, the number of adapters in /dev/dvb changed from one to three. Interaction between devices seemed to be pretty deterministic (I wasn't actually taking notes). Just booting again with same settings didn't change the outcome.

From this erratic behaviour I would suspect that the motherboard or tuners are doing something nonstandard, which messes up the plug and play process more or less badly. The BIOS has ability to reserve IRQ, so I shall try to do some googling to see, if I can configure the tuners more or less manually in Linux. If someone knows a good howto or something that could help me, I'd be happy.

-JLarja

I see that your capture cards are not listed at
http://www.mythtv.org/wiki/index.php/Vi ... ith_MythTV

In fact there are only 3 dvb-c cards listed there.

Do you know if anyone has ever gotten a Satelco Easywatch DVB-C PCI card to work with Mythtv?
If anyone has perhaps they could post here. Other wise maybe your card just isn't compatible.

I don't personally know anyone who has gotten MythTV to work, so all I got is what can be found online. http://linuxtv.org/wiki/index.php/DVB-C_PCI_Cards says Satelco etc. "works right out-of-the-box with KnoppMyth R5F27." Nothing about R5.5 unfortunately. When I bought those cards (on March I think), C-1501 didn't yet have Linux drivers (or so I was told, I didn't actually check very well myself).

Anyway, if I can't find a solution, I probably test those cards in my current gaming rig, which has an Intel Motherboard, Core 2 Duo and (unfortunately perhaps) Radeon 3870. Moving the cards is going to take some time (I have way too little room for this sort of build operations), so I have to wait for such a time that nothing needs to be recorded for a while.

Personally I'm starting to think that the motherboard has some unholy interactions with Radeon or the tuners. I checked the /proc/interrupts by the way, and always at least one of the cards (usually all) shares interrupts with either on-board devices or display card. This shouldn't be a problem, but if there is something wrong with either the motherboard, cards or drivers, it could be.

-JLarja

Finally, some progress.

The backend started to crash in a rather unpleasant way. It did not totally crash (the process was still alive), so my simple script couldn't restart it. Because of this, I decided that some drastic measures were in order.

I tested with my gaming rig, which is based on Intel DG33FB (G33 chipset), Core 2 Duo E8400 and Radeon HD 3870. In that setup, Mythfrontend was totally stable and myth-setup was quite stable. Unfortunately, playback didn't work very well: X used something like 190 percent of CPU and update speed was still only something like 10 frames per second. I think it was so stable, because everything was done in software, but I didn't know where to check if that was the case.

Next, I tried with Radeon X800XL: crash, crash, crash. This seemed to indicate conflict (at least) between X800XL and tuner cards. Then I decided to test with onboard GMA 3100: Knoppmyth CD wouldn't boot. With acpi=off and noapic installation succeeded, but only one of the processor cores worked. Everything seemed to be rock solid, even tuning in mythtv-setup worked ok, so I decided to test my original setup with acpi=off and noapic. This didn't help, since both cores were still recognized. Nosmp did the trick and now mythtv-setup is able to scan all channels without crashes.

Mythfrontend, however, is not in any better shape. It still crashes every time I return from watching live TV. Of course, I would also like to be able to benefit from both cores on my CPU, so situation is less than ideal. I don't know yet, if backend is more stable than before. I shall know in couple of days.

As I have described before, this setup has some BIOS level problems in device discovery. Intel system never exhibited anything like that and always found all the tuners. The actual problem seems to be some weird set of SMP incompatibilities. Remember, with HD 3870 frontend was solid, but unfortunately unable to playback at reasonable speed.

I think that there are three things I like to do next:

1. Google about MythTV and SMP problems. I vaguely remember seeing something like that before.

2. Test with A8N SLI, Opteron and HD 3870. With some digging I might be able to get X in better shape. Unfortunately, I am pretty certain that HD 3870 with its quite massive passive cooling setup isn't going to motherboard, due to large chipset cooler.

3. Go buy some cheap Nvidia video card and test with that.

Although, if backend is now stable, I might not be too interested to do anything. I won't be home much of the next week and after that my vacation is over. And you know, I might actually want watch some TV .

Anyway, if someone has some new ideas based on this SMP discovery, I'm all ears.

By the way, sorry about all the typos, inconsistencies and such. It is almost 4:30 AM here in Finland and I really need to get some sleep.

-JLarja

I would definitely start there. The price of the card is cheaper than the Rogaine required to replace all the pulled out hair!

...and the card will actually WORK! LOL!

_________________
Retired KM user (R4 - R6.04); friend to LH users.

Well, when I started this project, I was more interested in learning something new than actually getting a usable DVR. I started with just one tuner, all the other parts were "just something that I had laying around", most from my old gaming rig. Only later I bought two more tuners and remote controller. Of course, once you get used to MythTV, you really don't want to go back using some basic home electronics DVR.

Anyway, I'm still pretty philosophical about all this. It is a hobby of mine and I like it.

If, however, I just wanted to build a MythTV box, I would check recommended hardware and stick to that .

Edit: By the way, does it matter which GeForce to choose? Is there any practical difference in, for examole, HD playback capabilities?

-JLarja

Yes. The FX5200 is kind of on the line. If you've got a fast one with plenty of video memory it will do it, but some people have reported HDTV playback problems with the lower end ones using the doubled frame rates that certain deinterlacers require (e.g. Bob2x). For the faster GPUs the key is to make sure that they're not one of those models thats steals system RAM and also extra system bus cycles as a result.