Jittery HD only during live TV

[TBacker]

I know these forums are riddled withreports of jittery HD playback issues, but they all seem to pleague both playback of recorded material AND live TV.

In my case, I have no issue watching 1080i HD recorded shows, but theres just enough jitter in the video of live HD material to make it annoying / unwatchable. What really hurts is the picture is otherwise stunning!

Lower res live material is fine in live, just the 1080i jitters.

More symptoms / checks I've done....

* Audio is fine.
* I'm using the gbpvr.exe file dated 11/5/06.
* PureVideo decoders for both audio and video (June 06 release - forget the version).
* No other decoders are on the system.
* DirectX 9B version of quartz.dll
* The latest nVidia drivers released just days ago (made the problem better but not gone).
* CPU use is in the 40-50% range during live TV with 1080i source.
* PureVideo set for hardware acceleration, anamorphic / smart deinterlace / best avaialable / prever VMR9
* GB-PVR set for VMR9 Custom / live preview / no deinterlacing
* Have tried overlay mode to no avail.

So - now I'm stumped. I presently have to watch my HD stuff off of the old STB, or wait for it to record and watch it after it's done!

Input from the brain trust would be appreciated.

[Braklet]

* PureVideo set for hardware acceleration, anamorphic / smart deinterlace / best avaialable / prever VMR9
* GB-PVR set for VMR9 Custom / live preview / no deinterlacing
* Have tried overlay mode to no avail.

Had the exact same issues as you. My only success seemed to be a combination of configuring Overlay on both GB-PVR and PureVideo, and configuring GB-PVR playback for System Default. The latter means you have to ensure that DirectShow will use PureVideo as you expect. I'm still sorting all that out so can't offer a nice set of steps to ensure that it happens. If Windows Media Player can play the recorded HD with good quality, it should be possible to get GB-PVR to do the same even with Live TV.

Any other combination either gave me screwed up video due to the nVidia aspect ratio bug, or a large percentage of dropped frames.

Do you have an nVidia GPU based video card?

I suggest you get a copy of GSpot just to have some visibility into your DirectShow filters and as a test tool. I'm starting to learn the ropes with GraphEdit.
They won't necessarily fix your problems but they do provide insight.

[TBacker]

My only success seemed to be a combination of configuring Overlay on both GB-PVR and PureVideo, and configuring GB-PVR playback for System Default..

Thanks - I'll give that a try tonight.

Any other combination either gave me screwed up video due to the nVidia aspect ratio bug, or a large percentage of dropped frames.

What is the aspect ratio bug - that is the first I've heard of this....

Do you have an nVidia GPU based video card?

Yup - it's a Gigabyte fanless implemntation of the 7600GT GPU w/256 MB RAM

I suggest you get a copy of GSpot just to have some visibility into your DirectShow filters and as a test tool.

I got RadLight Filter Manager http://developer.radlight.net to verify video and audio filter / decoder settings and priorities, but haven't used it much beyond making sure that PurVideo had the highest merit.

Thanks for the quick reply - I'll report back on my testing...

Tim

[Braklet]

What is the aspect ratio bug - that is the first I've heard of this....

At some point in my endless configure/retune cycle, video was compressed in the upper left corner of the frame. The rest of the frame was taken up by large pink or black areas flecked with green. I asked about it on this forum and was told "it sounds like the nVidia aspect bug," so now I repeat the meme for your benefit.

Yup - it's a Gigabyte fanless implemntation of the 7600GT GPU w/256 MB RAM

That's much more memory bandwidth than mine (6600 GPU). I'd think it easily capable of HD reproduction. Your GPU load seems high to me. I have an Athlon 64 x2 but live HD play only eats maybe 10% (been a while since I checked). That might be a clue.

I'm curious about the fanless cards but will save that for another thread.

Also try opening up recorded media files with GraphEdit for curiosity's sake. It won't necessarily help isolate Live TV problems but does indicate what DirectShow thinks should happen by default.

Within the last day, sub told me that one of the logs, gbpvr-native perhaps, provides a textual representation of the filter graph used for Live TV. That'll give you even more information.

EDIT: here's a link to sub's post - http://forums.gbpvr.com/showpost.php?p=1...ostcount=2

[sub]

What is the aspect ratio bug - that is the first I've heard of this....

Its bug in the nvidia driver, which affects VMR when hardware accelleration is enabled. Discussed here: http://forums.nextpvr.com/showthread.php?t=16198

[TBacker]

Well, I tried switching GBPVR to default decoders with the nVidia decoders merit settings high as Braklet suggested, but it seemed to make no difference.

Tonight I brought my work laptop home so I could UlraVNC into the HTPC while watching it (allowing me to actualy be able to read Windows dialogs and tweak on the fly).

Good news - I got the jittering to stop on 1080i live TV by turning off hardware acceleration on the nVidia driver.

Bad news - motion is smooth, but the picture isn't as sharp and there are some motion artifacts (slight horizontal rolls or lines distorting the picture). I guess this is what other posters call "tearing"? In addition, GBPVR is now using 50% of my Pentium 4 3.2GHz processor - presumably because PureVideo is now fully running in software.

I'm a little perplexed as the PureVideo drivers are supposed to work better in concert with the 7600GT GPU I have, offloading from the processor and making faster "decisions", hence better picture quality.

BTW - My earlier post about original processor use (before these tests) was incorrect. GBPVR was only using 20% during 1080i live TV.

I am going to continue to experiment with settings, but I welcome further comments and input.

Once working, maybe I could post a quick "How To Get Here From There" for future GBPVR-ers...

Tim

[TBacker]

I was able to reactivate the hardware acceleration in the PureVideo decoder by switching deinterlacing to Automatic.

Live TV at 1080i still smooth, image quality is good. Processor is back down to <= 20%.

Still have failry regular rolls or tears when there is a scene change or fast pan. Hard to describe... The best description I can come up with is a split-second sharp horizontal line in the picture below which there are several blocks of picture information which lags behind the rest of the picture. Not pixellation, but "bloxellation".

Could be deinterlace errors of some kind...

What is strange is that I swear I used this combination of settings before with no positive results.

We'll watch some must see TV tonight and see how things go on multiple channels.

Tim

[Braklet]

What is strange is that I swear I used this combination of settings before with no positive results.

I've seen that sort of thing many times. GPU tuning does not seem to be very deterministic. In my case Smart vs. Automatic deinterlacing didn't seem to make a huge difference, so I went back to Smart.

IIRC under Automatic deinterlacing the decoder simply uses a static profile based on the media type (video or film). Under Smart deinterlacing it actually tries to tune deinterlacing in real time. That would tend to explain why cards might drop frames more often under Smart.

My 6600 actually performs better displaying full HD 1080i ATSC than it does playing SD material back over a 1080i ATSC channel. Viewing the exact same channel (CBS, 1080i), it stutters occasionally during Survivor (SD program), but rarely if ever stutters during CSI (HD program). I know that sounds counterintuitive, but I guess the GPU & decoder are working harder trying to smooth out the rough SD content.

[TBacker]

I have a feeling that the severity of the studdering problem also depends on what the local stations do to the network feeds.

Because they need to switch and possibly reencode the digital feeds at the station, there is room there for variability in equipment, processing, timing, etc.

The more errors or variability there is in the data stream, the more our equipment has to work to decode it and reconstruct a useable image.

I've reached a point where I can watch most 1080i programming with very few artifacts, but there is still programming that aggrivates the problem.

I can watch CSI in HD pretty smoothly now. On the other hand, Leno or Conan on NBC looks great but studders like a banshi....

I've got a dual core P4 processor on the way to see if true multithreading / multitasking will clean the rest of this issue up.

That's the last I can do for a while... I spent myself into oblivion on this thing :eek:

[diehard2]

The tearing during pans can only be remedied by the setting the VMR9 into exclusive mode. I believe sub is working on this. There was a thread around here somewhere about turning this on, but it didn't work so well after the first usage.