So I have older hardware that I was hoping to use as a front-end to my mythtv box I have setup. Currently the backend is in a server rack and is a beast. So there is no way that I could ever hope to use it as a true front end. I have a K6-2 500 with 384 mb of ram, Nvidia 5200 FX, pci live soundcard. I have everythign working but when I turn on xvmc I get a constant prebuffering pause error in the log and my audio seems to studder. The video does somewhat, but the audio is where you can really tell. With XvMC turned off the constant studder is gone, but is replaced by a severe studder every 2-3 seconds. I have seen ppl say that they have gotten knoppmyth to run on a 500mhz system, but yet to see anyone say how. If anyone can give me some direction of what I can do to get this working I would be eternally grateful.

Have you put extra audio buffering on in setup?

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Intel C2D 7400, Nvidia 5600 via HDMI to Samsung B37B650TW (PAL), Asus P5QL-E mobo, 4Gb PC6400 DDR2 ram, Samsung Spinpoint 500 Gb & 1Tb drive, Nova-HD-S2 (x2)

It was turned on by default. I have tried it with it on and off.

You really have to tell us what video stream type you are using? Is this mpeg-2 video from a hauppauge card? Or a DVB or ATSC stream? Or maybe you are transcoding into Xvid mpeg-4? For that matter are you only talking about myth recordings? Or does this happen in mythvideo also?

If you are using hauppauge mpeg-2 encoder cards for capture then you could easily get a pvr-350 for the frontend and have the playback hardware accelerated.

Also tell us about your nextwork please. If you're going through a 10Base-T hub, I think I found your problem. But I assume if you have a "server rack" in your house that wont be the problem.

Sorry about that. They are coming off a pvr 250 card to an mpeg2 file. I was originally running through 10base-t hub, but thought that could be a problem and went back to my 100mb switch.

Run nvidia-settings and turn off the options (there are three in mine, one on by default) for "Sync to VBlank". This should fix the Xvmc stutter. Note that nvidia-settings is not persistent, so you'll have to figure a way to run it on every X-server restart (I added a script in /etc/Xsession.d)

Interesting. I had tried that, but I'm not sure if I rebooted the box before I tested it or not. I will give it another go this evening and report back. Thx for the help.

I tried for weeks with all sorts of variations to get a 400MHz K6-3 system similar to what you describe to work and never could. Even with an NVidia card running the proprietary driver, the kernel and libc6 compiled for K6 architecture, MythTV compiled from source optimized for K6, every variation of parameter I could think of.

It just did not have the CPU horsepower/throughput necessary to playback video smoothly at decent quality levels (ie, 480 lines vertical). I tried overclocking, adding RAM, HD parameters, you name it. I could get marginally smooth quality 320x240 video but it still looked like doom and the audio was choppy as you describe.

However, when I tried it on P2 machines, even much slower CPUs and comparable hardware otherwise, I was able to get decent video playback and smoother audio.

I do not know why the K6's have so much trouble but I suspect it has something to do with the old socket 7 architecture compared to the newer P2 slot1/socket 370. I believe there are throughput limitations present in the socket 7, even with 100+ MHz FSBs, that somehow the next generation P2/P3 sockets (slot 1/socket 370) fixed.

Best of luck. I hate to throw cold water on your efforts but they sound so familiar. If you are able to get your system to work, please post how you did it. I would REALLY like to hear what the fix is.

Thanks

Andrew Lynch

unfortunately this did not help. Are the any other ideas out there?

Thats good to know. I have a friend that has a stock pile of old equipment that he has told me I'm welcome to. I'm sure he has some intel stuff. Would the celerons fair better do you imagine?

If I were you, I would review the hardware options available and pick a system based on the slot 1/socket 370 or socket A/socket 462. I think those systems seem to have a better chance of working compared to socket 7 regardless of raw CPU speed. I believe a slot 1 celeron would probably still beat a socket 7 pentium (K6) even for comparable or greater clock speed.

I have browsed the Tier 1 and Tier 2 forums and picked out the low end systems that have worked for people here. For the low end they mostly seem to be P2 or systems that use the slot 1/socket 370 and a few athlon (socket A/socket 462) sprinkled in as well.

If you get access to a variety of old hardware, check to see what socket the motherboard supports. It seems to me that it is more of a factor than raw CPU speed. For instance, 400MHz P2 seem OK but your 500MHz K6 is stuttering just like mine did.

Based on my experimenting, I am fairly confident that the CPU throughput was the limiting factor since I took various nuv files at different resolutions and formats. I played them back using the MythTV internal viewer and also using MPlayer (compiled for K6). With nothing else running in the background (no tuner recording, no network, etc) I still saw the problems with the video playback even with Xv enabled or even XvMC.

The other option is to get a PVR-350 and offload the video decoding entirely to it. However, it is not a cure-all though as the accelerated playback only applies to MPEG2 which severely restricts your PVR options (ie, all recordings must be in MPEG2). If you transcode to MPEG4 to save space, you will be back to the stuttering video. They are not cheap either at $125-$175 depending on where you get them.

Best of luck.

Andrew Lynch

Thanks for the advice. I got an Intel Celeron running @ 566 and it works like a charm. next step will be to buy the remote for it and finish my tweaks and then I will be good. Thanks all for everyone's help.