PureVideo, stutter, and a possible solution (for me)

[jbarr]

I've been struggling with stuttering on my SageTV setup using the PureVideo decoders, and I think I may have found a solution: Set PureVideo's de-interlace control setting to "Film". I tried the "Smart" and "Automatic" settings thinking that they would automatically handle the video type, but after some trial and error, it looks like "Film" is the answer (for my setup, anyway.)

Using "Smart" or "Automatic", some channels stutter and some don't. It's kind of hit-or-miss. But when I set PureVideo's de-interlace control to "Film", now every channel I have tried looks very smooth. I've tried low-end analog cable channels, "standard" digital cable channels, and higher "premium" channels, and they all look much, much better. Even the "crawls" on CNN and Fox News run across the bottom of the screen smoothly instead of the jerky way they used to. And "Star Trek: TNG" and "Star Trek: Voyager" episodes, shows that exhibited consistently jerky playback, are now significantly smoother.

Some of my basic settings:

Video Renderer: VMR9
MPEF2 Decoder: Default (thus using PureVideo)
Audio Renderer: Default
MPEG2 Audio Decoder Filter: SageTV MPEG Audio
Use FSE: Yes
3D Excelleration: Enabled

I know different people's setups vary greatly, and minor settings here or there can make a huge difference. I really can't explain why "Film" would work and "Smart" and "Automatic" won't, but I guess at this point, if the setting works, leave it alone and enjoy the show....

[blade]

Forcing film isn't a good idea because the content will not be handled correctly.

Automatic - The decoder reads the source type and automatically selects video or film mode, depending on the source.

Smart - Lets the decoder choose the best deinterlacing method to use and is the only method that does inverse telecine and bad edit detection.

Film - Forces film mode and does not apply de-interlacing.

Video - Forces video mode and applies de-interlacing.

[flavius]

Do you have any explanation why it does what it does for him?

[jbarr]

I tried again this morning testing various settings on various channels (raw analog, digital, and premium) and again, only "Film" played consistently without stutter.

I have no idea if it is related at all, but one thing I stumbled upon this morning was a possible solution to another Overlay playback error issue I have been having. In my case, any attempt to playback using Overlay failed. VMR9 was the only solution for any playback. This morning, I disabled 3D acceleration in SageTV's Advanced setup, and Overlay playback capabilities returned. I had to leave to go to work, so I'll test things out over the weekend, but that may be the answer to that issue.

If I can get overlay working, then I'm confident that I can get the stutter issue corrected, because as I recall, Overlay gave me much smoother playback. I'll let you know what I find.

[blade]

Originally Posted by flavius

Do you have any explanation why it does what it does for him?

1 - It's not doing any deinterlacing so it's going to be less taxing on the system. (Adaptive deinterlacing is very demanding. Selecting less demanding modes of deinterlacing can sometimes yield smoother playback.)
2 - When forcing film, playback is 30 fps for video where as with all the other settings video is 60 fps. So it's also less taxing on the system.

All of my experience is with Nvidia cards so I can't speak for any other cards.

I've tried the different modes myself and have seen film mode reduce stuttering. I've also seen how poorly it makes certain content look. Some of it is literally unwatchable and I'm not talking about opinion. I mean literally unwatchable by anyone's standards. People have tried this before and it has has been discussed on the forums before.

Trying to "fix" stuttering by applying the wrong method isn't a good solution. The only type of content that should potentially give problems is 1080i video because it's being played back at 60 fps and requires deinterlacing.

Even my lowly 6200 can easily playback all other types of content stutter free with VMR9 while outputting at 1080i resolution. If the card is stuttering with SD content something is definitely wrong somewhere.

[jbarr]

Originally Posted by blade

I've tried the different modes myself and have seen film mode reduce stuttering. I've also seen how poorly it makes certain content look. Some of it is literally unwatchable and I'm not talking about opinion. I mean literally unwatchable by anyone's standards.

Can you please elaborate on what what you mean by "unwatchable"? Are you referring to stutter? Picture Quality?

Originally Posted by blade

Trying to "fix" stuttering by applying the wrong method isn't a good solution. The only type of content that should potentially give problems is 1080i video because it's being played back at 60 fps and requires deinterlacing.

Even my lowly 6200 can easily playback all other types of content stutter free with VMR9 while outputting at 1080i resolution. If the card is stuttering with SD content something is definitely wrong somewhere.

I agree 100%. I know my system can perform well because DVD playback is stellar. I'll just have to troubleshoot step-by-step, isolating the problem.

And FYI, my resolution is set at 1366 x 768 , the maximum for my Westinghouse W420t 42" HD monitor. Do you recommend a different resolution?


While it may sound simplistic for veterans, I think the most difficult part is actually getting straight what components handle what aspect of the system. For example:

1.Hauppauge Capture card and drivers:
This controls what is recorded. This shouldn't affect playback in the least other than specific video settings (color, brightness, etc.) I'll ensure that there is nothing out of the ordinary here.

2. Video card and drivers:
This controls what is displayed and where. I'll check the configuration of this to see if anything is out of the ordinary.

3. nVIDIA PureVide decoder:
This controls how the video is decoded for display. Fortunately, there aren't many settings.

4. SageTV:
This kinda ties everything together by selecting what specific decoders and renderers are to be used for playback. The more I play with and read about the settings, the more I understand what the "proper" settings should be for my setup.

As I see it, the key in all this is really understanding just what actually affects playback, what to adjust, and what not to adjust. Unfortunately, out-of-the-box "default" settings are not always the best.

[blade]

Originally Posted by jbarr

Can you please elaborate on what what you mean by "unwatchable"? Are you referring to stutter? Picture Quality?

Terrible PQ. I don't mean a few artifacts here and there. I can't really describe it. For me the entire image was wavy and heavily distorted. It reminded me of a fun house mirror. Some content looked ok, but you'll know when you run across what I'm talking about.

And FYI, my resolution is set at 1366 x 768 , the maximum for my Westinghouse W420t 42" HD monitor. Do you recommend a different resolution?

If that is the native resolution then that is correct.

1.Hauppauge Capture card and drivers:
This controls what is recorded. This shouldn't affect playback in the least other than specific video settings (color, brightness, etc.) I'll ensure that there is nothing out of the ordinary here.

You may already know this, but the temporal and spatial settings can be adjusted via the hauppauge tweak tool. This can make a huge difference in PQ. If motion blur is too high you'll have ghosting and I believe I've heard if it's too low you can get stuttering. I think mine is close to 0 and I don't notice any stuttering so I'm not sure about that.

2. Video card and drivers:
This controls what is displayed and where. I'll check the configuration of this to see if anything is out of the ordinary.

3. nVIDIA PureVide decoder:
This controls how the video is decoded for display. Fortunately, there aren't many settings.

4. SageTV:
This kinda ties everything together by selecting what specific decoders and renderers are to be used for playback. The more I play with and read about the settings, the more I understand what the "proper" settings should be for my setup.

I used to have problems with stuttering on SD material and my systems still require FSE to get smooth playback with VMR9. With the newer versions of Sage, drivers, and decoders stuttering on SD is never an issue for me anymore thanks to FSE.

For HD I still have some problems and there are some really strange things going on with playback. I did a fresh install awhile back and everything was smooth and after a day or two 1080i video content began stuttering and I have been unable to fix it. I changed nothing during that time. It just broke.

Personally I'm waiting on the HD extender so I hopefully no longer have to put up with whatever is causing all of the problems. From my experience HD playback isn't anywhere near where it should be. I don't know what's to blame, but something isn't right somewhere.

If you haven't already tried it fraps can be handy when troubleshooting stuttering when using VMR9. It will show the actual frame rate.