I have had this issue in the past, but I never really got anywhere with my tweeking so I am going to try again.

Whenever I select the “watch tv option” the video is choppy, like it is dropping frames almost. Even if I pause it for awhile and let the buffer build up, it is still choppy. Its to the point where it is unwatchable. However, if I select ‘record this show’ and exit out of live tv, and start watching it under my ‘watch recordings’ screen, then everything seems to be fine, even while recording. It will even work fine if I catch up to live time in my recording.

So overall, I am not able to use my ‘watch tv’ function, which is a big bummer when I want to watch multiple channels at once.

Anyway, I have been searching the forums, and trying to fix this problem for awhile. Here are some facts that might help identify the root cause:

--I have DMA turned on in my hard drive, so that is not the issue
--I only notice the skipping when watching an HDTV broadcast, it seems to be fine on sdtv programs.
--I have all commflag stuff turned off. There are no jobs running while watching livetv


My system specs are below

Knoppmyth R5C7 with 0.19

Motherboard: MSI K8 Neo4 –F
CPU: AMD Athlon 64 3800+ (socket 939)
RAM: Corsair Value Select 1GB PC3200 400MHz DDR DIMM kit (2x512MB)
GRAPHICS CARD: ASUS Extreme N6200TC256/TD
SOUNDCARD: Chaintech AV-710 with optical S/PDIF
Tuner Card 1: Airstar HD-5000
Tuner Card 2: Airstar HD-5000
HDD: 500 GB Seagate ATA 100 Ultra
DVD-RW: SAMSUNG|SH-S162L

I had a few ideas of what the root cause could be. Please feel free to rule out some of these possibilities, I am just brainstorming.

--My NVIDIA or graphics card drivers are not setup correctly
--my XF86config-4 file is not setup correctly
-- My ATA ultra cannot handle the strain of HDTV, even with DMA turned on
--There could be other DMA settings that I need to activate
-- I do not have enough processor or RAM speed to handle live hdtv.

As long as we are on the topic, I cannot even use picture-in-picture with my two tuner cards, instead of skipping frames, it simply pauses for about 15 seconds before moving to the next frame in each window. I think the two issues might be related.


Thanks in advance for any help you can provide. I am really beating my head against the wall, and would love to solve this issue.

Your hardware looks OK to me.

I didn't see above whether you have video processing set to 'XvMC' and 'Bob' which make a big difference in processor loading (which is the usual culprit in this type of complaint.)

I am using 'Kernal (less motion blurr)' for my algorithm, libmpeg2 as my mpeg2 decoder, I have enabled OpenGl vertical sync for timing, and I am not using XvMC in any way.

Well, try it, this is a YMMV thing, the others didn't work well for me and XvMC did... I use a Nvidia5200 card and a 3.2 ghz Pentium 4 however.

Are you getting the 'nvidia flash' at bootup ?

Yes I do get the Nvidia splash when I boot up. I am using the Nvidia 8762 drivers.

When I did the initial install of knoppmyth I choose not to include XvMC somewhere in the install, I dont know if that will screw things up. I will try XvMC when I get home and report back. Although I dont have really high hopes, you are the first person I know of that has HDTV working with XvMC.

Well, I tried every option of algorithm and decoder. XvMC did not work for me at all. The video wouldnt play, just a change of frames every 10 seconds or so. What are some other ideas, could it be my Nvidia drivers? I am using the newer nvidia 8762 drivers, and I wonder if this is the problem. It looks like other people on the forum have had trouble with this driver too. But it also seems that people have had trouble switching back to older drivers too, so I dont know what to do. I am trying to explore any option. Any other ideas anyone?

I had a similar problem with similar hardware. Here is what worked for me:

Under Knoppmyth playback setup:
disable "enable OpenGL vertical sync for timing" on the first page.

Run nvidia-settings:
under OpenGL settings
disable "sync to vblank"

I will try this when I get home tonight and report back. Thanks!

Have you tried other deinterlacers like linear blend? That system is just on the cusp of being fast enough to use kernel.

Sorry for not responding to my progress yet. I had to go out of town unexpectedly, and have not had a chance to work on my myth system. I will give the linear blend thing a shot, and the GLsync mentioned above.

No luck. I tried to turn off openGl vertical sync in both myth and Nvidia-settings. I also have tried every other de-interlacer with no luck. The worst part is my WAF is slowly going down. Any other ideas?

Did you ever resolve this issue? I am having the exact same problem under R5D1.

No I never resolved it. I just gave up. My resolution is going to be getting a 4500+ amd dual core and another gig of RAM.