24p and audio sync issues - Printable Version
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- bobo1on1 - 2010-10-07 22:47
No, because the clock gets vblank signals at 23.976 hertz, but interprets them as 24 hertz, which means the clock runs 0.1% too slow.
- neurosis13 - 2010-10-08 03:10
so what's need to be done to get the audio in sync then ?
- TheSwissKnife - 2010-10-09 04:11
bobo1on1 Wrote:Yes, because it was 0.1% too slow to start with, why is this so difficult for people to understand?
Because it is not very intuitive. I am sure there is a good reason but without knowing that reason, it is hard to understand why not just build the clock to the closest standard rate eg 24.00000 or 23.976024 in the first place, then adjust sync/clock based on that. I guess the reason might be that it is too difficult to this accurately enough quickly enough at movie start.
In the end though it only matters when people are trying to understand in order to fix the sync the issues.
- kulprit - 2010-10-09 05:24
Yeah it might be coming out that we can't understand it because really we just aren't technical enough. But even though this might all be working, we still have a sync issue of -200ms in a wide group of people all of a sudden.
Sounds like unrelated issues, the first is not even an issue because it is more than likely (99.99%) correct.
- Ronald Pagan - 2010-10-31 17:32
I can confirm that I have this issue as well on Dharma beta 4. (It isn`t a new issue however, I`ve been experiencing it since Babylon)
edit: whoops I have this issue on xbmc live not windows, although it seems like the exact same so it must not be OS specific
- Nektarios - 2010-11-01 03:00
I also have this problem. Will there be a solution?
- a11599 - 2010-11-12 23:07
I also experience this on my Panasonic plasma which has no such video enhancement features. So I have put together a patch, which automatically adds a -250 ms delay (works great for me) to the one which is set for the movie for low fps video modes when sync refreshrate is enabled.
Here it is:
To stress again, this is not a nice solution, just a dirty workaround to fix the behavior on my system, but might also be useful to others. Not tested on anything other than windows, but I think it should work on other platforms also.
ps.: If -250 ms does not suit your setup, you can change -0.25f to the value you prefer in the line which says:
g_settings.m_currentVideoSettings.m_GlobalAudioDelay = -0.25f;
- gav1577 - 2010-11-13 01:33
Same here i get the sync problem with my sony lcd at 24p. Im glad i found this thread because for a long time i thought my tv was broken. Strange how only 24p causes this problem, anyone tried with mpc or other player? i don't think its xbmc specific problem
- steelman1991 - 2010-11-13 10:53
In my experience, it is. Tried with mpc-hc and media portal and neither exhibit the problem, though both have other playback issues.
- gav1577 - 2010-11-13 15:33
steelman1991 Wrote:In my experience, it is. Tried with mpc-hc and media portal and neither exhibit the problem, though both have other playback issues.
Ok i stand corrected i can confirm using mpchc i have no sync problems
I tried the audio delay of 250 in xbmc and it does seem to fix the problem.
- neil.j1983 - 2010-11-13 18:55
gav1577 Wrote:Ok i stand corrected i can confirm using mpchc i have no sync problems
but then it puts 25fps videos out of sync. living in pal land, there's no ideal fix. i have mapped a button to audio sync adjust as my work around.
I imagine the devs will leave it till the new audio branch is done?
- Voyager - 2010-11-14 09:36
a11599 Wrote:To stress again, this is not a nice solution, just a dirty workaround to fix the behavior on my system, but might also be useful to others. Not tested on anything other than windows, but I think it should work on other platforms also.I tried this and it works very nicely for me. I don't have to configure the audio delay anymore for my HD 24p movies manually.
I think this workaround could be improved by taking parameters from advancedsettings.xml, e.g. the magnitude of the delay in ms (0 means that it's turned off) and the threshold (which you coded at 26). This way such solution could actually make it into SVN...
the fix - mikenova - 2010-11-14 09:55
Here comes a newbie question..
Where do i put the fix?
- Voyager - 2010-11-15 11:52
you can only apply such fixes (patches) if you have an SVN client and your own build environment.
- gav1577 - 2010-11-15 17:03
After doing some testing with a 250ms audio delay i found i would get random stutters and alot of dropped frames. Especially after skipping through a movie
about a second after i skip forward the video would stutter and drop about 3-5 frames sometimes more. If i reset the delay back to 0 no more dropped frames and smooth video again. Although setting the delay fixes the problem with sync
the random stutters/dropped frames are annoying so went back to using 50hz
refresh and and video (resync audio) i can live with the 4% speed up don't really notice it tbh