Warning, I'm a noobie to Knoppmyth and Linux....

I autoinstalled knoppmyth onto Dell Inspiron PC >2 GHz, >300 mb Ram; GeForce MX4000 128MB PCI w composite video out to SDTV. I chose 800x600 auto installation for my SD TV. HDHomeRun tuner.

Channels, especially HD channels, play with some stuttering, but OSD makes playback -- and OS -- stutter nearly to a halt until after any OSD goes away. Same with playback of recordings. Closed-captioning impossible stutter and stopping of display. (HDHomeRun plays HD fine in VLC on Windows XP, so it is not a bandwidth issue). Myth TV-Playback settings: Least stuttering with "CPU--" choice. OpenGL enabled only worsens things.

Is it the card, can it not deal with processing incoming digital HD? What's bogging things down? Anything I can do to improve with configurations? Ideas? Help!

Thank you!

300 MB might be too little memory. I have a gigabyte in my mythbox and it does HD from the HDHomeRun quite well. You can run "top" in an xterm while viewing HD to get an idea of what's going on.

The HDHomeRun outputs an MPEG2 stream. The computer doesn't have to do much work to store the incoming stream, but it has to do a lot of work to decode and view it.

One thing about the HDHomeRun that I didn't know initially is that it is sensitive to wireless interference. I used to get a lot of stuttering on HD recordings when it was sitting right next to my wireless router. I moved it a few feet away and now it works flawlessly.

Thanks Hari, I'll try more ram next. (Everything else hardware-wise seems good to you?)

Indeed, I know it's not the HDHomeRun unit itself, because it plays beautifully via VLC on windows XP box. Knoppmyth box: TOP shows CPU bouncing around 80 some percent when viewing TV or stored videos.

Thanks for all the tips and info. That's good to know how the MPG2 flows. All about the decoding -- would jive with how the box performs. Seems to record streams fine.

(P.S. I don't understand the "CPU++, CPU--" et al settings in playback, but choosing "CPU--" seems to help somewhat. Somewhat. But besides stuttering, OSD grinds playback to a halt until OSD goes away - quite ugly).

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Knoppmyth R6 Preview auto - Dell Dimension 2400 2.4 GHz - 1.2gb ram - Sparkle GeForce 8400GS (was MX4000 128MB) PCI TV-out - HDHomeRun dual ATSC over gigabit. It's not Greek to me, just Linux

Arrrrgh! I went out (Fry's is 30 miles out) to buy ram today. I now have 1.2 GB ram.... and, no difference! Still stuttering.

In top, there are two mythtv processes. When playing ATSC video, frontend is 80-90 percent, backend is eating the remaining 10 percent. The 2.4 GHz CPU is totally maxed. Doesn't matter how low I have the screen resolution set.

Help!

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Knoppmyth R6 Preview auto - Dell Dimension 2400 2.4 GHz - 1.2gb ram - Sparkle GeForce 8400GS (was MX4000 128MB) PCI TV-out - HDHomeRun dual ATSC over gigabit. It's not Greek to me, just Linux

Sorry to hear more RAM didn't help. If you want video card recommendations, the "Tier 1" forum here is a great resource. I wasn't sure if your CPU was fast enough for HD; I guess not.

This won't help with LiveTV, but a workaround is to transcode the recordings to a lower resolution, and then watch those recordings later. That's not very satisfying, since you might have to wait an hour or more after a recording is made to watch it, but it would put less load on your computer while watching.

In my opinion, a 2.4 GHz CPU is fine for playing back HD, IF your video card can manage it, and IF you have XvMC running.

When you are playing back HD content, and you bring up the on-screen display (menus, pausing playback, etc.) is the on-screen display color or black and white? If it's color then you are not using XvMC; if it's black and white you are.

I'm not sure whether your using TV out is a complicating factor--you're basically taking HD video and scaling it down considerably smaller in order to run via TV out -- but I can definitely say that I'm playing back HD material on an Athlon XP 2400+ (which is running at considerably less than 2.4 GHz) via VGA to a LCD TV at 800x600 resolution.

Check which Nvidia drivers can be used with your video card, and in turn if those drivers support XvMC.

http://www.mythtv.org/wiki/index.php/XvMC

Also check this section to see if your xorg.conf file has the appropriate settings to turn XvMC on

http://www.mythtv.org/wiki/index.php/Xv ... _xorg.conf

Thank goodness OSD is B&W! It is keyed small white text standout on shaded semi-transparent gray/black horizontal bars, right? Anything to avoid updating driver again (Remember, I'm a scary nooB here.... I tried to update 96.43.05 Feb 2008 to 96.43.07 newest, July 2008, as per UpdateNvidiaDrivers wiki. It either wasn't compatible or changed configs so that whenever X started, NVidia logo screen blinked a few times then went black. So I tried installing 96.43.05 again via same process, and it didn't fix. No idea where to look, so I ran Knoppmyth 5.5 autoinstall from scratch again (wipes drive, fresh install of everything), figured it would take less time than days of trying to learn and sleuth what changed. ) ANYhoo...



Even the thumbnail preview video in the recordings list seems to max Frontend. Probably a decoding issue? (BTW, what is mythcommflag? I notice that it is growing to 80+ percent of my CPU whenever frontend is doing nothing, ie when not playing video. When frontend is playing video, mythcommflag drops to like .3%.)



I just trancoded recording (while playing, chose "menu" "begin trancoding" choosing autoinstall's default "low quality" -- I think I got the process right). How do I know when it's done it? No feedback, no information that says this is a trancoded file. Anyway, twenty minutes later, seems it does help playback stuttering, except when OSD is on, then it stutters, jerking probably around 25% speed. So does that make it a display issue instead of processing issue? Both? (Oops, playback just stuttered a moment in background as I write this. Back to normal. Sigh.)

UPDATE: I now see the ".nuv" extensions and smaller filesizes. I see it working now (thx)



B&W OSD on my system it seems... so I should be okay, don't need to make config changes? (I already added one, the "UseEvents" thing mentioned in UpdateNvidiaDrivers as a speed tweak.)

Feeling tentative after a few wipe-reinstalls....

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Knoppmyth R6 Preview auto - Dell Dimension 2400 2.4 GHz - 1.2gb ram - Sparkle GeForce 8400GS (was MX4000 128MB) PCI TV-out - HDHomeRun dual ATSC over gigabit. It's not Greek to me, just Linux

It scans your recordings, flagging commercials for later skipping or editing. It is VERY CPU-intensive, particularly with HD programming, so it gets out of the way when you are not watching TV.

Re: your OSD. Somewhere in that XvMC link there is information on making sure that it does not fade on or off, and making sure it's not transparent, for slower machines. I would try to turn off transparency and fading to try to help playback.

Ultimately I think the culprit, however, is the video card. How new is that? I wish I had encyclopaedic knowledge of Nvidia model numbers, but it seems like an old card.

EDIT: Also, to see if it's the TV-out, can you connect a computer monitor to your system, turn off video out, and see how it performs?

** UPDATE **

Re: Auto-Trancode, I think I got it. Doesn't work, though, if you enable record during Live-TV. But it's progress!

Still of course flummoxed by stuttering of ATSC stream decoding and display. Accounts here are that my hardware is up to snuff. ??Transcoding experiments tell me this:

Low Quality trancoding helps somewhat, but problem not there only when low quality and bitrate media also resized to 480x480 -- so seems decoding as well as display are at play. Somehow.

----- Original Message -----



I'm grappling with this:
http://www.mythtv.org/docs/mythtv-HOWTO-23.html#ss23.14

...and getting all flummoxed. Is it possible to set up things so that all recordings (except live tv streaming) are automatically transcoded, without having to change these settings per recording?

UPDATE: I got it. Was just a bit confused by.... things.

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Knoppmyth R6 Preview auto - Dell Dimension 2400 2.4 GHz - 1.2gb ram - Sparkle GeForce 8400GS (was MX4000 128MB) PCI TV-out - HDHomeRun dual ATSC over gigabit. It's not Greek to me, just Linux

an MX4000 is a fairly old nvidia card.
that may be not enough horsepower for HD especially with it converting to tv-out.

Other items might be needing to ensure hdparm is enabled on the hard disk.

Actually memory tells me that there is a Chromakey OSD option that gives color with XvMC. I forget the details but searching for those terms may help.

Thanks, bigbro! And tjc!



What mean?



But heck, if it's b&w, then should be XvMC, right?

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Knoppmyth R6 Preview auto - Dell Dimension 2400 2.4 GHz - 1.2gb ram - Sparkle GeForce 8400GS (was MX4000 128MB) PCI TV-out - HDHomeRun dual ATSC over gigabit. It's not Greek to me, just Linux

I minimun recommedation for a video card and HD is a GeForce 5200. You'll also want to use XvMC.

Doesn't Knoppmyth autoconfigure to use XvMC already?

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Knoppmyth R6 Preview auto - Dell Dimension 2400 2.4 GHz - 1.2gb ram - Sparkle GeForce 8400GS (was MX4000 128MB) PCI TV-out - HDHomeRun dual ATSC over gigabit. It's not Greek to me, just Linux

http://www.knoppmythwiki.org/index.php?page=HardDrives

If DMA is not enabled on your hard drive, it can cause performance issues like stuttering. I think this is more important for DVD playback (a whole other can of worms) but could be coming into play here, so check your HD.




Yes, but as cesman points out, it's likely your video card is underpowered. It really is quite an old model, and a GeForce 5200 PCI is $35 from NewEgg.

http://www.newegg.com/Product/Product.a ... 6814130188

Not sure if KnoppMyth autoconfigures XvMC but it's pretty trivial to enable it (edit xorg.conf as described above). It might be autoconfigured for Nvidia cards but ATI cards (I think) still can't use XvMC so it wouldn't turn it on for those video cards.

Also, the Chromakey OSD only works for certain Nvidia cards.

http://www.mythtv.org/wiki/XvMC#OSD