video av sync problems
#1
Hi, I really like the xbmc because of its advanced gui and just the right media center feeling, but, I'm havin problems with the audio and video sync playback using 720p and 1080p material, mkv to be exact. Here is the deal, cpu usage is barely over 50% so that is not the problem, not to mention that mediaportal plays them fine.
Main problem, as I see it is that the 24p material needs 24hz refresh rate to play without jitter, and 25p material needs 50hz refresh rate to play fine. Since xbmc and no other for that matter switch the refresh rate automatically, we have jitter. Now, if my RR is 24hz and I try to play 25p material, xbmc with vertical sync on, tries to compensate, but jitters - a/v sync is getting bigger as the movie plays along. If my RR is 24hz and I play 24p material, it starts with 0.9s a/v sync delay which is corrected by skipping..
Now, if I disable vertical sync i get perfect a/v sync but the picture has tearing - stripes - half a picture - typical for no vertycal sync..
This is a huge problem. I tried using xbmc launcher and setting refresh rate manually to 24 or 50hz depending on the material I watch using Display Changer (great little utility) but sometimes xbmc minimises so this is an quick and ugly fix.
I see that no media center has a working solution for this, and this affects probably ALL people having their media centers hookep up to plasma or lcd tv. bluray comes mostly with 24p, sometimes 25p, pal dvdrip is 25fps, ntsc is 29.97fps...
Can't you make some sort of script that detects or reads the framerate from the file and asks you do you want to match your refresh rate to the movie frame rate using Display Changer?
And this av sync is pretty bad... I get none of this using external codecs in mediaportal.. I like xbmc better because it's more fancy Smile but mediaportal just works..
Or am I doing something wrong? anyway, keep up the great work you aredoing now..
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#2
Sounds like the gfx driver is syncing to the wrong display. Dig around in the driver control panel and see if it won't let you change it.

Note: FPS and Refresh Rate are not related or comparable!
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#3
I don't get the graphic driver part... Not syncing what exactly? I can change refresh rate as I want..

Sure they are related if you have a plasma screen connected. If you play 24fps bluray with 50hz refresh rate, you get frame drops. If you set the output to 24hz you get perfect playback. Same thing applies to 25fps video. You can get it smooth at 50hz output, not 24hz and not 60hz.

I get a/v sync problems in all scenarios, except when the 24fps is played on 24hz refresh rate, I can correct the delay, on every other refresh rate, a/v sync gets worse by the second..
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#4
I'm saying the card can only sync to vertical retrace on one display. So we'll be drawing as if we're on that display (framerate wise) regardless of which one you've dragged the window to.
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#5
I only have one display - 42" plasma fullhd tv.. And vertical syncing works, but a/v sync does not. When the vertical sync is off, a/v sync is fine but there is heavy tearing.
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#6
I have exactly the same problem, changing everything in drivers, but nothing help Undecided
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#7
yeah, the problem persists, I thought maybe it was caused by directvobsub so I disabled it (it has been known to cause a/v delay) but still no change.. reverted back to mediaportal and playing everything fine... shame
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#8
I have sync issues if the high quality software upscaling is enabled. Try disabling that if it is enabled and see if that helps.
HTPC: ZBOX-ID41 running OpenElec with Logitech Harmony remote.
NAS: Lian Li Cube, MSI P55-CD53, Intel I7-880, 16GB RAM, 23x 2TB WD drives @ RAID6, 500GB Samsung, Ubuntu Linux.
TV: Samsung UE75ES9005
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#9
I agree with you akiaki.
If xbmc is not able to automatically switch between different refresh rates, it's a huge problem for people that have both HD (24p) and PAL (25p) materials.
I hope this auto switch will be soon implemented. If not, I'll have to find another software for my HTPC Sad

I'm a former user of xbmc on xbox. This software is very good and I'll be very happy to be able to use it on my HTPC...

Fred.
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