Hey everyone,

I know I've seen this bandied about time and time again, but I've tried all the solutions I've found (so far) and none of them really applied to my problem perfectly, so I'm hoping someone can help or point me somewhere I missed.

Let me start by saying I'm not running KnoppMyth, I'm running mythTV on Ubuntu, using the Ubuntu mythtv sources from apt-get. I'm saying this upfront because I don't want to mislead anyone and I don't want to be down the line and have someone say, "Well, you should just install KnoppMyth, then come back." I'm posting here because you all seem to be good at general MythTV issues, not just KM.

Anyhow, my problem is this:
I ran all the configuration stuff to get HD running on my box, along with the proper resolution hacks (which took forever) for my TV to go 720p on DVI, and the XvMC stuff. Now I'm not topping off my CPU (although it can get close sometimes), and everything looks good. However, when I go to view a recorded TV show in myth, I get choppy sound and video (although the logs seem to point to the video playback being slow, and the audio being delayed to "keep up" with it).

Here's the kicker: If I play the recorded mpg files from the recorded shows directory in Kaffeine or Totem (mplayer?), they play back fine (great actually), even while the backend is recording another show. From viewing the playback logs, XVMC seems to be enabled and working properly, and the OSD goes to gray (which is another indication, AFAIK).

I'm a newbie, btw, as I'm sure you've figured out by now. I could use some help.

My hardware is: Athlon64 3200+ (or so, forget exactly), a mobo with GeFroce 6150 integrated graphics (with 128 system mem being thrown at it), and a gig of dual channel RAM. I'm running everything on a dedicated 500GB Sata 3GB/s drive. I've no idea if it's got DMA enabled, where is that option anyway?

Thanks.

Is it only during playback of recorded shows, or during LiveTV as well?

I don't believe DMA applies to SATA, someone will correct me if I'm wrong.

What motherboard and HDTV card(s) are you using?

I have an A64 3200+ in an Asus M2NPV-VM with 1Gb RAM (I gave the onboard video 256Mb to play with). I use Bob deinterlacing and have set "Preferred MPEG2 decoder" to Standard, and can play HD content (both recorded and "Live") just fine. Lesser CPUs may have a problem, so knowing exactly what you have may help determine where the problem lies. This is on a KnoppMyth R5D1 + MythTV .20 frontend, I'm not sure how your version correlates.

Both LiveTV and recorded, in the internal player.

MSI K8NGM2-FID and a DVico Fusion RT Gold.. but the recordings are fine if I watch them in another player, so I know it's recording fine.

I have it set to Standard XvMC. Before I set it there, it seemed to be using a lot of CPU. I could be wrong. Mythtv is 0.20, but no idea which version of that (aka SVN), or what modifications were made by the Ubuntu-mythTV team.

Oh, and it's an Ahtlon64 3000+. Sorry about the confusion. But I tried my 3800+ X2 from my upstairs computer in it and it didn't help.

Thanks for the help, by the way.

I've made no more progress on this as of this point, but the other features I see working on mythTV (mythweb is awesome!) make me very happy, and make me want to make this player work. Since playback works outside of mythtv with the backend recording, I'm thinking it's not my hardware specs but rather some sort of codec issue. What codec(s) does myth use for the internal player, and how could I update them?

Thanks all.

It looks like you have enabled XVMC which is known to be temperamental. Have you tried disabling XVMC and to see what happens? An Athlon 64 3000+ might be a bit week for HD without XVMC but when you say that dropping a 3800+ in didn't make any difference I start to heavily suspect that XVMC is your issue.

In the interests of science would you disable XVMC and let us know what happens? Ideally you should try to play something in 720p to rule out the 3000+ as the bottleneck.

Martian

_________________
ABIT NF-M2 nView | Athlon 64 X2 3800+ | 2GB DDR2 800 | HDHomerun | GeForce 6150 (onboard) | WD 640 GB SATA HD | DVD-RW (sata) | StreamZap IR receiver with Logitech Harmony remote

Vizio 37" LCD HDTV (1080p)

After disabling XvMC, the video quality got much smoother for everything. Digital SD signals play back perfectly. HD signals, on the other hand, play a little slow. It's MUCH smoother than with XvMC enabled, but you can make out tiny pauses in the stream which make it seem like it's playing a bit below the actual framerate. Running these files in Kaffeine (before I hadn't checked an HD program) is smooth as silk. I'm assuming Kaffeine has XvMC working properly, but I'm not sure. Back to the internal player, the CPU utilization for the SD content was around 50%; for HD, more like 80%. The backend wasn't currently recording, so I don't know if it would get worse with it doing so, but I can only imagine it would.

Summary, XvMC definitely caused the stuttering, but without it my CPU isn't good enough. Anyone think a newer build (aka fresh from the svn) might help these issues at all? Since I'm no good at linux, would a make install replace the appropriate things, or do I have to apt-get uninstall or somesuch before building the new version? Would this frag my existing recordings?

Any hints on the playback issue? Specifically, optimizations I might have missed that would speed up the internal player?

Lastly, a while ago I ran a command that supposedly made mythfrontend run with root priveleges in order to use the real-time threads. How can I verify this? What's the command to give it these priveleges? (I can't find it now).

Thanks!

when viewing in myth, have you tried pausing and starting again. Just one second pause seems to smooth the waters for me especially in 720p. dont know why... you can even FF to 'catch up' and it's fine, just needs the initial pause/start. On recordings I don't see this problem as much as LiveTV.

I played the same game where I could play HD content just fine with everything except the MythTV player. You can seee the "fun" in this thread; http://mysettopbox.tv/phpBB2/viewtopic.php?t=12629

You could try SVN to see if there are any improvements. There is a helper script you may be able to use; http://mysettopbox.tv/phpBB2/viewtopic.php?t=11985 - Not sure if it would apply to your configuration.

"More oomph" Specifically, more CPU power seemed to do it for me. The rule of thumb, according to what I have found here and on other forums, is P4 3.0Ghz or equivalent (or higher) with 1Gb RAM. I went with the A64 3200+ because I found others on these forums that were using it successfully for HDTV playback. My next frontend will be using an X2 3800+ just to make sure I have enough processing power.

I tried the pause trick, it didn't help with XvMC playback.

I disabled real-time threads and opengl vsync and bob deint, and I can get a very watchable HD program now, hooray. I'm not sure if this will still be the case with a concurrent recording, but we'll see when it happens.

I've enjoyed myth enough now to throw some more money at hardware to improve things. In the meantime, I might see if I can fix this XvMC issue in mythtv, if no one else is working on it (I'm actually a Computer Science guy with a good deal of programming experience, nearly with my Ph.D., and I work in image processing )... if anyone has leads on who to contact about helping please let me know. I'll run over to the website and figure stuff out on my own after finals, but in case anyone here knows how the dev efforts are going (aka has inside info), I figured I'd ask.

Thanks for everyone's help.

In the best interest of "throwing money at the problem" I highly recommend you pick up this Athlon 64 X2 3800+ from Fry's for $64.99.

http://www.frys.com/product/4907541

That should solve all of your problems

Martian

_________________
ABIT NF-M2 nView | Athlon 64 X2 3800+ | 2GB DDR2 800 | HDHomerun | GeForce 6150 (onboard) | WD 640 GB SATA HD | DVD-RW (sata) | StreamZap IR receiver with Logitech Harmony remote

Vizio 37" LCD HDTV (1080p)

Oooohh, good catch! Looks like my next frontend will be up and running sooner than I thought...