Jittery Video?

dteirney, can you check if my findings below are the same for you?

Hitcher Wrote:Ah, we're getting somewhere.

I turned off 'High Quality Upscaling' to lessen the load on my HTPC and both 23.98fps and 25fps videos were showing 60fps. Again I tried the override but no change.

After much testing (and a lot of WTH moments) I've finally figured out what it's doing on my system.


It only uses the start up refresh rate of XBMC as the fps of any video - even changing the GUI refresh rate during testing will have no effect unless XBMC is then shutdown and restarted.

I'm definitely having the refresh rate change because I ran into the issue in http://forum.xbmc.org/showthread.php?p=2...post290935.

My startup frequency is set to 60Hz, and playback for most content is switching to 50Hz (most of our stuff is PAL).

I only had one resolution that had a series of frequencies "known" to XBMC.

I've got High Quality Upscaling turned off as well.

I'm starting xbmc with the -fs flag (for full screen). Not sure if that makes any difference. The resolution set in XBMC isn't the "xyz (Full Screen)" resolution.

not wanting to go grave digging but i still have this bug.
a video with 30fps (on a 60hz tv) plays buttery smooth in vlc but lags and jitters something dreafull in xbmc
was there ever any solution found?

pseudoheld Wrote:not wanting to go grave digging but i still have this bug.
a video with 30fps (on a 60hz tv) plays buttery smooth in vlc but lags and jitters something dreafull in xbmc
was there ever any solution found?

The only solution I found was to use an external media player. I run on windows and I've found that configuration XBMC to use Media Player Classic Home Cinema ("MPC-HC") will work ifyou configure MPC-HC to use the power-dvd video codec, which takes full advantage of the Nvidia ION's ability to do hardware decoding and de-interlacing.

A key root cause of these problems is that NTSC / ATSC can use multiple interlacing techniques (simple even/odd interlacing; telecined; random "non-standard" variations on the usual Telecine pattern.

I am headed back to mythtv from my frontend. The XBMC frontend is a much more aesthetically pleasing interface, but the folks in mythtv land sorted all these issues out years ago. After a year on XBMC as my frontend, I find that the improved aesthetics are not worth the pain caused by a lack of proper support for deinterlacing & closed caption decoding.

Marc


Marc

thats a shame that this bug still hasn't been fixed completely then.
interestingly i only have this bug on fps. mostly its videos with 30fps almost all others play with no problems at all...
i find this pretty strange, seen as my tv runs on 60hz (like most LCD TVs) and 60 is a plural of 30 so you would think it should be easy to produce smooth playback

any other ideas?

pseudoheld Wrote:interestingly i only have this bug on fps. mostly its videos with 30fps almost all others play with no problems at all...
i find this pretty strange, seen as my tv runs on 60hz (like most LCD TVs) and 60 is a plural of 30 so you would think it should be easy to produce smooth playback

Generally speaking, there are 3 types of video out there: Progressive scan, interlaced and telecined. XBMC's player will do well with progress scan and interlaced material but gets into trouble with telecined material.

Telecined material will be 30fps by the time you see it. "Telecine" is typically applied to content originally recorded with film. Film is typically (always?) 24 fps, progressive. NTSC video is 30fps, interlaced. Telecine is a method of converting 24fps progressive material to 30fps interlaced and have it play smoothly on a interlaced-display TV set. This whole process was created in the days of pre-HD TV sets, but still impacts a lot of what is transmitted over the air and available on DVD.

Typical material that is not telecined: Shows recorded in front of a live audience; news shows; weather shows; talk shows; TV comedies filmed in front of a live audience; game shows; etc. More generally, anything that was filmed using video equipment instead of film.

Typical material that is telecined: Movies & TV shows not filmed in front of a live audience. (ie, JAG, Desperate Housewives; Brothers & Sisters, etc). More generally, anything that was recorded with film and then converted to video.

As time marches on the industry is moving away from film & all TV's are capable of displaying progressive scan material. Perhaps at some point all telecined material will be a thing of the past, but it will be many years (decades?) before this happens.

Two useful references that explain more about the process:

http://www.mplayerhq.hu/DOCS/HTML/en/men...ecine.html

http://en.wikipedia.org/wiki/Telecine

I can't say for certain this is the problem you are having, but I can say with certainty that the problem I have outlined has been present in XBMC's native player for many years and as far as I can tell has not been addressed as for version 10.1. XBMC needs a native player that can detect what type of video it is dealing with "on the fly" and adjust accordingly. MYTHTV's player does this.

thanks mate that was a very informative post! +rep for you.
i had another closer look at the files im having problems with in vlc and the codec info says it has 30.00056 (or sth like that) frames. so maybe its just a badly encoded file. but its still aparent that vlc handles this much better than xbmc.