Go Back   nV News Forums > Linux Support Forums > NVIDIA Linux

Newegg Daily Deals

Reply
 
Thread Tools
Old 06-02-10, 05:44 PM   #1
fernandezm
Registered User
 
Join Date: Jan 2003
Posts: 12
Lightbulb Nvidia ION + VDPAU = Stuttering HD video

Hi there,

I recently bought an Asus AT3N7A-I which comes with an Intel Atom 330 + Nvidia ION chip, to use it as a HTPC. I installed Ubuntu 10.04, nvidia drivers, the vdpau package and mplayer from repositories.

Everything seemed to be alright, but there was some problems/artifacts with HD video decoding... first, tearing; also, the playback wasn't "smooth", it was something like "jumping" or dropping frames (but mplayer didn't output anything related in console).

After I worked around the tearing effect disabling the Composite extension inside xorg.conf, I was getting a very annoying "sttutering" playback, no matter if it was a 720p or 1080p movie, like I said before.

I installed the last nvidia-beta drivers (256.x), compiled the last mplayer from git repositories, and nothing resolved the problem, until I went into the XBMC forum (exactly here)...

Following those instructions, I disabled the auto-edid config from nvidia drivers and added some custom modelines in xorg.conf (the most important is 1920x1080@24 fps)... and now my movies (which are 23.976 fps) look very, very smooth! All I have to do is select the @24fps modeline in System->Preferences->Display.

The question is, why is so hard to find the answer and/or getting 24fps movies look smooth in 60fps display configurations?

And more importantly, Nvidia, are you aware of this problem/bug? Will you resolve it?

I'm available to send more debug info, (qvdpautest benchmark for example, or anything you need)...

Thanks a lot, I hope this helps someone else.

Regards
fernandezm is offline   Reply With Quote
Old 06-02-10, 06:24 PM   #2
Stephen Warren
Moderator
 
Stephen Warren's Avatar
 
Join Date: Aug 2005
Posts: 1,327
Default Re: Nvidia ION + VDPAU = Stuttering HD video

When a video is played on a display of a higher frame-rate, video images need to be repeated for some number of display periods. If this isn't done, the video will play much too fast. For 24fps content on a 60Hz display, you'll end up displaying image A for 2 frame periods, then image B for 3 frame periods, then C for 2, then D for 3, and so on. This cadence is commonly referred to as "judder". Is this what you're seeing, or is the problem more serious?
Stephen Warren is offline   Reply With Quote
Old 06-02-10, 06:37 PM   #3
fernandezm
Registered User
 
Join Date: Jan 2003
Posts: 12
Smile Re: Nvidia ION + VDPAU = Stuttering HD video

Quote:
Originally Posted by Stephen Warren View Post
When a video is played on a display of a higher frame-rate, video images need to be repeated for some number of display periods. If this isn't done, the video will play much too fast. For 24fps content on a 60Hz display, you'll end up displaying image A for 2 frame periods, then image B for 3 frame periods, then C for 2, then D for 3, and so on. This cadence is commonly referred to as "judder". Is this what you're seeing, or is the problem more serious?
Great, I didn't know the technical name... yes, I was getting clearly the "judder" effect, like this Youtube example...

How can I avoid this problem? (remember, I'm playing a 23.976fps movie at 60fps)... I searched again in this forum and found this... do I have to interlace the movie?

If I can avoid this problem I don't have to hack inside the xorg.conf file and obtain new modelines for my screen...

Thanks! (very quick answer too).

Regards
fernandezm is offline   Reply With Quote
Old 06-03-10, 10:31 AM   #4
Stephen Warren
Moderator
 
Stephen Warren's Avatar
 
Join Date: Aug 2005
Posts: 1,327
Default Re: Nvidia ION + VDPAU = Stuttering HD video

I'm not sure that Youtube example actually shows what's typically referred to as judder; judder isn't something that comes and goes.

For the effect that really is judder, in general, there's not a lot that can be done about it; it's a fact of life when displaying content encoded at one frame-rate one a display of another frame-rate. One alternative would be to use a display rate that is an exact multiple of the encoded video frame-rate. For example, when you used a 24Hz modeline, that was 1x the frame rate, it looked OK. Using a 48, 96, 120Hz frame-rate should also work, but probably isn't supported by your display device.

(I think XBMC has an option to switch the display frame-rate based on encoded frame-rate for this very reason)
Stephen Warren is offline   Reply With Quote
Old 06-03-10, 11:02 AM   #5
fernandezm
Registered User
 
Join Date: Jan 2003
Posts: 12
Default Re: Nvidia ION + VDPAU = Stuttering HD video

Quote:
Originally Posted by Stephen Warren View Post
I'm not sure that Youtube example actually shows what's typically referred to as judder; judder isn't something that comes and goes.
Well, sorry to say the opposite, but I had exactly the same behavior from the example; the judder came and went generally in smooth big landscape scenes, or in some actor close-ups... but it happened eventually, not in the rest of the video, and definitely not in fast/action scenes. It didn't happened all the time, just like that youtube example. So, are you not sure this is judder? Anyway, I solved it lowering the fps of my display to 24Hz... What else could it be?

Quote:
Originally Posted by Stephen Warren View Post
For the effect that really is judder, in general, there's not a lot that can be done about it; it's a fact of life when displaying content encoded at one frame-rate one a display of another frame-rate. One alternative would be to use a display rate that is an exact multiple of the encoded video frame-rate. For example, when you used a 24Hz modeline, that was 1x the frame rate, it looked OK. Using a 48, 96, 120Hz frame-rate should also work, but probably isn't supported by your display device.
You're right, my display doesn't support 48 Hz or 96 Hz, just 24, 25, 30, 50 and 60. The problem I see is, why I didn't have those modelines available in my Nvidia-Settings application when it asked aboud EDID modes? It shouldn't be hard to let the user select it from the GUI...

This simple change could make easier the life of any linux user not being able to hack around the xorg.conf file... I think there should be a lot of other cases like mine.

Another question I have about my case is, could mplayer do something about it? Preprocessing the video, interlacing it, or <insert your anti-judder-effect-here>? there is a lot of low level issues I don't fully understand and I think all this stuff could be simpler to the non technical user...

Quote:
Originally Posted by Stephen Warren View Post
(I think XBMC has an option to switch the display frame-rate based on encoded frame-rate for this very reason)
Yes, they have it, but X should have the modeline available. If one sees in Nvidia-settings the option to change the refresh rate you can watch movies in your couch in just four or five clicks... ;-)

Thank you for your help

Regards
fernandezm is offline   Reply With Quote
Old 06-04-10, 04:43 PM   #6
Stephen Warren
Moderator
 
Stephen Warren's Avatar
 
Join Date: Aug 2005
Posts: 1,327
Default Re: Nvidia ION + VDPAU = Stuttering HD video

Quote:
Originally Posted by fernandezm View Post
Well, sorry to say the opposite, but I had exactly the same behavior from the example; the judder came and went generally in smooth big landscape scenes, or in some actor close-ups... but it happened eventually, not in the rest of the video, and definitely not in fast/action scenes. It didn't happened all the time, just like that youtube example. So, are you not sure this is judder?
Judder definitely doesn't come and go, although it is more noticeable with fast motion. The Youtube clip looks more serious than judder; it looks like frames were not displayed or something; probably a bad interaction between the content and the TV's video processing algorithms. The poster of the Youtube clip probably just used the wrong word to describe his/her issue.

Quote:
Originally Posted by fernandezm View Post
Another question I have about my case is, could mplayer do something about it?
MPlayer can't do anything about judder; it's a fact of life. It's simply not possible to display each frame for an equal amount of time when the content is 24Hz and the display 60Hz. That said, I have no idea how relevant that is to your issue, since we don't know if you have/don't-have judder vs. something else.

Quote:
Originally Posted by fernandezm View Post
Yes, they have it, but X should have the modeline available. If one sees in Nvidia-settings the option to change the refresh rate you can watch movies in your couch in just four or five clicks... ;-)
I imagine your TV's EDID is incorrectly configured, or simply doesn't have space to describe all the modes that the TV accepts. Without EDID information or xorg.conf entries, it's impossible for the driver to know what modes the TV supports.
Stephen Warren is offline   Reply With Quote
Old 06-05-10, 02:16 PM   #7
farbird
Registered User
 
Join Date: Feb 2010
Posts: 15
Default Re: Nvidia ION + VDPAU = Stuttering HD video

there is a script that will make sure your display output 1080p rather than using the 60hz.

http://forum.xbmc.org/showthread.php?t=70068
farbird is offline   Reply With Quote
Old 11-19-10, 09:30 AM   #8
mlord
Linux kernel hacker
 
Join Date: Feb 2009
Location: Ottawa, Canada
Posts: 173
Default Re: Nvidia ION + VDPAU = Stuttering HD video

My new Zotac HD-ID11 "Ion2" system was also stuttering with some 1080i content in MythTV (Advanced/2x) when I first set it up. The problem was cured by telling MythTV to use two (2) threads for decoding/playback rather than the default of one (1) thread.

Perhaps something similar might work here?
Your original Ion system probably isn't quite as quick for VDPAU as the next-gen Ion2 is, so you may have to drop back a notch on the quality settings. Depending upon what qvdpautest says for it.

Cheers
mlord is offline   Reply With Quote

Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 04:41 PM.


Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 1998 - 2014, nV News.