help on frame skipping

[wgf_bean]

I’ve just purchased and installed an "ATI TV Wonder 650". My CPU is an AMD 2800+. The video card uses an "NVIDIA GeForce 6800 GT", which comes with hardware MPEG-2 decoding.

I’m new to Beyond TV but from reading on the forum I have a common problem that others have had: frame skipping. I found this link:
http://www.snapstream.com/community/Articles/decoders/

This 4 year old post has this listed combination:

System:AMD 1700+
Encoder:PVR250
Decoder:nvDVD
Video Card:nVidia GeForce 4 MX440
Quality Profile:DVD High-Res
CPU Usage:15%

With my hardware the CPU Usage is more like 55-70%. It never peaks to 100%, but I still get frame skipping. Audio is fine. I have found no setting for quality profile. I’m sure BTV is different than it was when the older post was done.

I have a faster CPU, have hardware encode and decode, have the latest drives for both, yet my performance is much worse. My signal strength is fine. I would appreciate any tips to fix the frame skipping.

[Killer Bob]

Try turning on Overlay.... That will lower your CPU usage by quite a bit. Are you trying to do HD?

[wgf_bean]

Originally Posted by Killer Bob

Try turning on Overlay.... That will lower your CPU usage by quite a bit. Are you trying to do HD?

It's already set to Overlay.
I'm trying to view 1080i broadcasts.

Would love to solve this as I want to record football when it starts this weekend.

Also I have:

1G system RAM
256M non-shared video RAM
500G HD SATA dedicated to BTV

[queonda]

Try playing in VLC or WMP to see if you still have the problem.
Also, search the forums for your Nvidia card (i have no experience here), I hear newer drivers may not be better than older drivers for HD playback.
Not sure if BTV uses the hardware decoder.

[wgf_bean]

I see no setting for VLC or WMP. What are they?

I'm viewing live.

I did see that some people have better luck with older drivers. I can try uninstalling, and using the original install disk - if I can find it!

[queonda]

AH, you say live tv, What happens when you record the show and playback? I meant try different video players ( VLC and Windows Media Player) to see if it's a problem with playback in BTV or displaying out your video card.

You may also try the exclusivefs switch. http://snapstream.helpserve.com/inde...articleid=1142

[wgf_bean]

OK. I tried recording, then playback (with BTV stopped of course). I get the same skips at the same locations. Perhaps it's a signal strength issue and I'm just not used to the symptoms since I'm new to HDTV. Depending on what I'm watching sometimes it's only once or twice a minute that I see it. Sometimes every second. I was attributing this to higher or lower definition content.

Now where do I check the signal strength without going through the set up to rescan all the channels? Must be in the BTV interface somewhere...

[Killer Bob]

I was afraid that you were doing HD, My hunch is that your 2800 proc is borderline for HD, Your vid card should handle it but with your processor running as hard as it is to keep up, Im thinking that might be the issue. Especially if your getting the same thing recording as you are watching live. When I made the move to HD I upgraded everything.

[wgf_bean]

Originally Posted by Killer Bob

When I made the move to HD I upgraded everything.

What did you have for a CPU before you upgraded?

[kandlg]

Run your test one more time without watching the show while you record it. Just go into the guide and record the show and go back and watch it AFTER it is finished recording. Post 7 makes it look like you watched it while it was recording and then played it back. Since watching requires a lot of CPU, you want to take that out of the equation. When you play it back, if it still has dropped frames skip back and see if the drops are always in the same place. If yes, recording issue. If not, it is a playback issue.

When you record an HDTV stream the computer is simply transferring the MPG stream directly to the hard drive. There is no encoding involved so your processor should have little or no load. If you are experiencing dropped frames at the same point everytime on a recorded show then it is probably the recording process and it is probably a signal issue. Playback issues are generally random. A longshot, but it might be that your hard drive has dropped into PIO mode - check your sata or ide controller and make sure it is in DMA mode.

[wgf_bean]

kandlg, thanks for the tips. I'll try more tests when I get home from work tonight. I suspect signal issues. My cable system doesn't have HDTV so I'm using a Terrestrial Digital DB8 UHF HDTV Antenna with a Channel Master CM 7778 Titan2 VHF/UHF Preamplifier

http://www.solidsignal.com/prod_display.asp?PROD=TD-DB8

http://www.solidsignal.com/prod_disp...=&PROD=ANC7778

This high gain antenna coupled with the preamplifier is necessary for me to pull in the stations in my area. However I haven't yet mounted them very high to clear the trees. Since I'm not line of sight yet and not aimed optimally, I might be getting some multi-path reception, which if it gets bad enough could explain the issues I have. I’m used to a friends set (also in the town I live in) which shows jpeg artifacting when his signal strength gets in trouble – you know, the square boxes, etc. Perhaps this ATI Theater 650 PRO shows it differently by opting to freeze the image while it resyncs rather than showing it breaking down into squares.

The hard drive is in DMA mode. Running a test it sustains a little over 50M/sec which should be more than enough. If I'm doing my math right, recording at 8G/hour=2.2M/sec, which is less than 5% of the drive's ability.

I have a novice question. I've been watching 1080i broadcast which are perfect except for the occasional frame skipping / pausing. Tomorrow night will be the first football game of the season so I'll get to test the system with a much more active image. The question is how do the broadcast stations make use of their bandwidth? Does regular 1080i show like a sit com use the same bandwidth as a sports show also broadcast in 1080i which has significantly higher video activity? In other words does the broadcaster make use of all the available bandwidth and simply increase the detail on a sit com, where as decrease the detail slightly on a sports event to maintain bandwidth? If the answer is they use more bandwidth on a sports event, then I may expect to see the problem I am experiencing get worse.

[Killer Bob]

Originally Posted by wgf_bean

What did you have for a CPU before you upgraded?

I had a 754 pin 3g mobile athlon (ran at 1800 mgz) --- with the same vid card that you got. It handled reg TV ok but I didnt want to chance it with HD. Now that 3g mobile chip is one generation ahead of the 2800 chip that your running.

I upgraded to the 3800x2 chip and I love it... They are cheap the MB's have come way down in price and for doing a HTPC I think they are very cost effecient. But I did go PCIE on the vid card and spent a few bucks there....

[wgf_bean]

I ran a test without watching the show while record it. The CPU usage is 5-15%. The frame skipping is still there, but is very much related to the channel I watch and aiming the antenna. Sometimes it’s as infrequent as once or twice a minute. I'm 22 miles from the broadcaster, but I also have woods with 55 foot trees only 100 feet from my antenna. I haven't yet mounted the antenna high. It's only 20 feet off the ground. I could easily be getting multi-path. So I don't think there's a driver or software issue, but rather my signal source.

One thing we lose when we go to HDTV is the ability to "see" what's wrong with the signal. On analog TV it's easy to recognize multi-path because of the ghosting it generates. In fact there are all sorts of different types of interference. A trained eye can look at the picture and know what needs correcting. This doesn't seem to be so with HDTV. Is anyone aware of a way to diagnose signal problems on HDTV? I.e., recognize that a problem is multi-path, signal overload, interference from another source, etc.?