Playback jerky ONLY on one channel, why?

[tradergordo]

I've been very happy with GBPVR, using HDHomeRun. It took me a long time to get it all setup, but I think I'm 95% of the way there. Everything seemed to be looking great, but for some reason during Sunday's NFL football games, I noticed that playback was jerky (dropped frames) only on CBS, scrolling text (ticker type) was clearly jerky. But on other channels like NBC it is smooth as silk including scrolling text. On regular non-PC based, digital set top box TV, CBS playback was fine with no jerkyness. I'm using the latest version of GBPVR (1.4.7), ATI mpeg video decoder, TS Mux. There are no audio problems. What could be causing the low frame rate only on one channel? Signal strength is not a problem, this is a very good signal.

Hardware: AMD Phenom 9850 Quad-Core 2.5GHz w/ 4 gigs RAM running windows server 2008 64 bit.

[Graham]

Ninetynine times out of ten, jerkiness is a playback issue and not a recording issue.

Have tried VMR Full screen exlusive and EVR in Video renderer on the Playbak tab of Config?

Is hardware acceleration on in the video decoder? Press the button beside the decoder option on the playback tab.

[pBS]

is it antenna source or QAM?
a certain channel only points to reception...[assuming you have more than one ch. with same resolution]
there's still a lot of shuffling around of broadcast strength, late upgrades etc..

record it and check recording in vlc or MPCHC...
if ok it's decoders...
if not ok, probably ant. adjustments
if qam, may have to rescan for changes...

[Snooze]

during Sunday's NFL football games, I noticed that playback was jerky (dropped frames) only on CBS, scrolling text (ticker type) was clearly jerky. But on other channels like NBC it is smooth as silk including scrolling text.

Hi. I am just going to share my experience with Digital Brodcast over QAM on Charter. Everything displayed fairly well. EXCEPT when I invited the guys over to watch hockey or football in digital. It seemed these events have a higher frame rate or something, you know to catch all the action since everything moves so fast (puck, ball etc.), kinda like using a camcorder that you can set the shutter speed depending on what you are filming.

Anyway, I was using a ATI HD2400 PCI (since I had onboard video and no AGP slots available). As much as I hated to admit it, my hardware (video card) just could not keep up with the action. I am thinking the power on the PCI bus just couldnt do what the card demanded.

I since upgraded to a newer system I found on ebay with a PCIE x16 video card, using the same HVR-1600 tuner and I am so happy I did. I do not see the jerky frames anymore.

I do not know if this is your problem, but when I read your post, that is all I could think of when it was me over a year ago. It was only during live games broadcasting 1080i w/ AC3 on QAM.

As you can see by the signature below, I wanted to make sure this would not become an issue for a while again

[tradergordo]

Yea, you could be right. I am using antenna, by the way, but like I said, the signal is rock solid, I've been watching digital TV via antenna literally for 10 years (was an early adopter in '99, believe it or not, Monday night football was in high def that year! Back before ABC moved MNF to ESPN). On my non-PC based TVs it looks perfect. Even on other channels football looks perfect. It must be something CBS is doing (it is 1080i AC3), maybe they are sending just a bit more data than the other guys? Not sure.

I'm using the onboard ATI HD3200. I did try other decoders (ATI one, Cyberlink, etc) but that didn't seem to change the situation. I will try the record and playback with VLC to see what happens next time I observe the issue. Maybe need to upgrade my video card, but was hoping that was not the case, want to keep power consumption as low as possible.

[martint123]

try recording that channel when it is happening and run something like MediaInfo on it and compare the datarates with a channel that plays fine.

http://mediainfo.sourceforge.net/en

[dshoup]

I'll second pBS's comment. I use an antenna and find occasional problems with the digital broadcasts...either the broadcaster has issues (i.e., I have good signal strength, but still get poor reception) or something unusual happens on some shows with my reception (signal normally strong but becomes weak...perhaps due to poor weather at the signal tower even when my weather is not bad).

I can discern it is not a playback issue by playing recorded files with the problem using VLC media player. It often shows with a lot of macroblocking in VLC...an obvious reception problem, not a playback issue. When I play the file with GBPVR, it uses the nVidia decoder and this decoder does a very good job of removing artifacts so the picture looks good...but is jerky (some times sound cuts in and out as well). Your ATI decoder may also be removing artifacts that would clue you in this is a reception issue.

You might download VLC (it's free) and try using it to play files that have this issue to see if it appears to be a reception problem. If so, you probably have no solution other than to try to improve your antenna...but even that may not work if the broadcaster is sending out a bad signal (which I suspect is the case some times when I see this despite having a good signal strength). I feel your pain!

[JBreits]

I also have ATI HD3200 onboard video and had tons of startup issues with 1080i channels. The 720p channels played flawlessly but 1080i channels were so choppy it was not watchable. I tried several decoders (ATI, cyberlink, etc), but I finally narrowed it down to the deinterlacing going on in the hardware. It's almost like the HD3200 doesn't have enough power to deinterlace a 1080i signal.

I eventually switched codecs to the one of the Media Player Classic Home Cinema standalone filters (I think it was the Gabest mpeg decoder, but I'd have to double check). It doesn't use hardware assisted deinterlacing so my CPU usage is up in the 50-60% range for a 1080i station, but it works and there's still enough CPU left to record, etc (I have a dual core AMD).

JBreits

[tradergordo]

That's an interesting comment, because I've also noticed that 720p content is flawless, and 1080p (blu-ray) is also flawless. So I was thinking dang, if it can do flawless 1080p then why would it have problems with some 1080i content? I guess it could have something to do with the deinterlacing on the HD3200... I'll try the codec you mentioned.

I also have ATI HD3200 onboard video and had tons of startup issues with 1080i channels. The 720p channels played flawlessly but 1080i channels were so choppy it was not watchable. I tried several decoders (ATI, cyberlink, etc), but I finally narrowed it down to the deinterlacing going on in the hardware. It's almost like the HD3200 doesn't have enough power to deinterlace a 1080i signal.

I eventually switched codecs to the one of the Media Player Classic Home Cinema standalone filters (I think it was the Gabest mpeg decoder, but I'd have to double check). It doesn't use hardware assisted deinterlacing so my CPU usage is up in the 50-60% range for a 1080i station, but it works and there's still enough CPU left to record, etc (I have a dual core AMD).

JBreits

[Deusxmachina]

An ATI 2400 was mentioned. I have a number of posts around here from when I was battling a 2400pro and deinterlacing. It just didn't have the oomph. I was told by some other users the card should be able to at least do Bob deinterlacing no problem, and I think in some testing I did get that to work fine, but I could never get it to work well with GBPVR for whatever reason.

Watching the card's gpu with monitoring software, it would max out and then the picture would stutter or whatever. Using Weave deinterlacing (basically, it's not doing any deinterlacing, which is fine for most movies, actually), everything worked good enough to be watchable, albeit with some mice teeth/jagged edges on fast motion.

So if anyone is having what is likely deinterlacing problems, be it from a maxed-out gpu or whatever, try setting deinterlacing to Weave. It might at least become watchable until you figure out something better.