2011-01-25, 12:19
nice post.. it's always good to know which HW platforms to avoid 
2011-01-25, 13:33
Thanks for this post, I'm not the only one going crazy about this judder/hiccups no one else seems to notice.
I have an Asrock 330, so my XBMC setup is running on an ION platform with VDPAU support. I came to the point where I found the "perfect" modline that supports 23.976 and everythings is runnings smoothly BUT 720p HDTV rips. SD is running fine, 1080p h264 BD rips are running fine, but for some unknown reason TV material gets those awful hiccups.
I seem to have the right modline since SD is playing without hiccups and VDPAU seems to be working fine since 1080p BD rips also play fine.
Anyone has experienced something similar?
I have an Asrock 330, so my XBMC setup is running on an ION platform with VDPAU support. I came to the point where I found the "perfect" modline that supports 23.976 and everythings is runnings smoothly BUT 720p HDTV rips. SD is running fine, 1080p h264 BD rips are running fine, but for some unknown reason TV material gets those awful hiccups.
I seem to have the right modline since SD is playing without hiccups and VDPAU seems to be working fine since 1080p BD rips also play fine.
Anyone has experienced something similar?
2011-01-25, 21:26
Ronner Wrote:I'm seriously starting to doubt whether or not this method is going to help me get rid of my "slomo"/skip/judder moments with whatever material I watch. Sometimes it runs fine for minutes and then suddenly it's showing it's ugly face and other times it's apparent pretty soon after I start a movie. It will "slomo" for a bit, and then continue to be smooth again, or it skips a frame or so.
I've tried quite a few ModeLine settings but to no avail. I'm having this on two systems, both top notch hardware to be able to play 1080p flawlessly with either vdpau or cpu only, but no matter what I do, I can not seem to get rid of the said effects and it's driving me completely nuts.
Why did I never have any problems with this on the windows platform, but on Linux this is a major pain in the ass? Is it solely due to Xorg? Or is this a combination of nvidia drivers with xorg?
Whatever it may be it's very very frustrating because I know perfect smooth playback is possible, but I simply can't seem to get it right on two very capable systems on two different TV's that have no problems doing 24p when I was using windows and xbmc.
Could this problem have anything to do with CPU Throttling? Which I sorta doubt cuz with VDPAU the cpu usage is no more than 1.5 to 3 %
It does sound like you're having a different issue. If you haven't tried disabling CPU Throttling yet I think it is probably worth a shot. I'd agree that your CPU is more than powerful enough in your situation I think it's the variation in speeds that cause these problems and not the lack of speed from being throttled back. If you want to run the CPU at a lower speed then force it to the speed you want and don't allow the system to change it automatically.
IIRC SD video should be running at 29.97p (59.97i? please correct me here someone) rather than 23.976? If you've got the adjust refresh rate to match video setting on this would cause you to be using a different xorg modeline for SD.
2011-01-25, 21:38
kolja Wrote:Very entertaining read, but you have one fact wrong:
Usually movies on BluRay are also in 23.976fps. True 24fps on BluRay is part of the standard, but I have never seen it in reality. Use a tool like mediainfo to check which framerate your movies have.
See: http://en.wikipedia.org/wiki/BluRay#Video
You're absolutely right. I actually work in the film/tv industry and had believed we authored everything meant for the big screen to 24fps. I'm a computer technology guy though and not in production. I'm going to pop over and pester one of the editors and see what they have to say about it. If we're down converting from 24fps to 23.976 for Blu Ray releases I wonder if and or how we're dealing with the slight frame rate mismatch and the occasional "extra" frame.
I'll let you know what I find out from that conversation and will eventually get a wiki article written up on this whole subject.
2011-01-25, 23:13
simonp Wrote:It does sound like you're having a different issue. If you haven't tried disabling CPU Throttling yet I think it is probably worth a shot. I'd agree that your CPU is more than powerful enough in your situation I think it's the variation in speeds that cause these problems and not the lack of speed from being throttled back. If you want to run the CPU at a lower speed then force it to the speed you want and don't allow the system to change it automatically.
IIRC SD video should be running at 29.97p (59.97i? please correct me here someone) rather than 23.976? If you've got the adjust refresh rate to match video setting on this would cause you to be using a different xorg modeline for SD.
I actually seem to have a lot better results following the blogpost here: http://openelec.tv/forum/12-guides-tips-...hz-support
From the list it produced I chose the ones with CEA-861B in it and remarkably have not had any "slo-mo"/judder/skips just yet and runs smooth. My samsung TV also indicates it's doing 1920x1080@24p so the switching does in fact take place. Also on other framerates I see my samsung switching to that mode accordingly. My philips downstairs does not give any feedback on what mode it's currently running but as the screen goes black for a second or so while switching rates and I have a pretty keen eye for viewing whether the tv is actually doing 24p or not I can tell that the philips is switching accordingly as well.
Did not have any of the mentioned problems so far on both sets so, so far so good
edit: As a sidenote, I did not do the "Sync playback to display"using "A/V sync method Video clock (Resample audio)" part of the guide.
2011-01-27, 21:08
those slight 'skips' means a frame is probably dropped, and should result in a dropped frame on the status screen, no?
For me, the default 24p mode with 23.976 material causes irregular frame drops, about 400 for a full 720p x264 movie which is EXTREMELY annoying, especially on a tv with frame interpolation. when i use a modeline (same specs except 2746 as htotal instead of 2750), i get much fewer drops but instead a few slight pause stutters also.
I've tried on both ION and ION2 machines with the same result.
This really, really, really, really needs to be fixed!
edit: i get drops regardless of which kind of speedup synchronization i use.
For me, the default 24p mode with 23.976 material causes irregular frame drops, about 400 for a full 720p x264 movie which is EXTREMELY annoying, especially on a tv with frame interpolation. when i use a modeline (same specs except 2746 as htotal instead of 2750), i get much fewer drops but instead a few slight pause stutters also.
I've tried on both ION and ION2 machines with the same result.
This really, really, really, really needs to be fixed!
edit: i get drops regardless of which kind of speedup synchronization i use.
2011-01-27, 21:36
I've noticed that dropped frames are different than "missed" frames for the synchronisation code. I don't get a lot of dropped frames, but I was getting the missed frames and a noticeable stutter before I made that 2746 change. Now the missed number still changes occasionally, but I don't seem to see it on screen. It's been pretty darn solid since making that change.
If you're getting drops that's usually because your machine can't decode fast enough. I'm pretty sure those numbers on change when the frames are dropped during decoding, and not during display. I could be wrong...
If you're getting drops that's usually because your machine can't decode fast enough. I'm pretty sure those numbers on change when the frames are dropped during decoding, and not during display. I could be wrong...
