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24p and audio sync issues
hrm disbling vsync and choosing software rendering as mentioned before here also help a little but I'm too paranoid atm - can't help alsways triple-checking if everything is in sync
edit: is it me or is there less lag in plex home theater although that's technically just an xbmc fork? Anyway - since it misses a lot of xbmc features and plug-ins I guess I'll forgo 24p output for the time being and let the pc convert everything to 60hz. Not the ideal solution but I guess I can live with it....

I'd miss xbmc too much otherwise Big Grin
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(2014-05-23, 16:00)belongamick Wrote: Just in case this fixes the issue for anyone else.

I had av sync issues with 24p content for the longest time - but for me it was resolved in 13.0. BUT ONLY if I use these settings:

enable adjust display refresh rate to match playback
and enable Sync Playback to Display
and use A/V Sync method Audio Clock

I am bistreaming audio to my Yamaha AMP using wasapi.

If I disable A/V Sync then the issue comes back.

Pressing o during playback shows a missed counter which increments by 1 or 2 per hour, or if I pause it runaway increments until I resume playback.

I'm using an AMD 5450 graphics card.

but i remember: if you sync to audio clock you loose digital audio (DTS) because the software reencode the audio stream. or is this fixed?
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(2014-05-11, 21:29)FernetMenta Wrote: could you try this build and post log: http://mirrors.xbmc.org/test-builds/win3...-win32.exe

I gave this a shot with the Disney Wow calibration disc (good resource for AV sync testing) and was not able to detect any difference from a vanilla Gotham build. My setup requires about 125ms delay when displaying at 24hz (xbmc adjusting display).

FernetMenta, did this build contain a possible fix, or just instrumentation for logging?

Happy to do some more testing. Having a calibration video makes it a lot easier than staring at people speaking.

-Dustin
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(2014-05-23, 16:00)belongamick Wrote: Just in case this fixes the issue for anyone else.

I had av sync issues with 24p content for the longest time - but for me it was resolved in 13.0. BUT ONLY if I use these settings:

enable adjust display refresh rate to match playback
and enable Sync Playback to Display
and use A/V Sync method Audio Clock

I am bistreaming audio to my Yamaha AMP using wasapi.

If I disable A/V Sync then the issue comes back.

Pressing o during playback shows a missed counter which increments by 1 or 2 per hour, or if I pause it runaway increments until I resume playback.

I'm using an AMD 5450 graphics card.

Odd. I have the same graphics card, and 13 introduced sync problems on 24 fps material for me. Detailed here at http://forum.xbmc.org/showthread.php?tid=195453. I found a partial solution, but haven't had a real chance to test it while watching something straight through. I'm sticking with Frodo for now unfortunately.
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(2014-05-25, 02:28)dustobub Wrote: I gave this a shot with the Disney Wow calibration disc (good resource for AV sync testing) and was not able to detect any difference from a vanilla Gotham build. My setup requires about 125ms delay when displaying at 24hz (xbmc adjusting display).

FernetMenta, did this build contain a possible fix, or just instrumentation for logging?

Happy to do some more testing. Having a calibration video makes it a lot easier than staring at people speaking.

-Dustin

There are several reasons for a/v desync related to audio latency. This value may be wrong for some reason:

1) AVR or TV have not reported the actual value back to the PC
2) The video/audio driver does not read the value passed in extended EDID
3) The value changed due to switch of refresh rate

Most systems struggle with 2) and can be cured with an entry in advanced settings. The mentioned build would fix 3). Would you have a debug log?
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Setting/increasing "pause during refresh rate change" to 0.7 seconds was a gamechanger for me.
I used to get different delays with different material (all 24hz). Mostly my global delay of 285ms was perfect, but sometimes I needed to add an additional delay of 285ms, leading me to think that the global delay was infact not active. By allowing time for the refresh rate change to take effect, this is now working for me. The magic pause number will vary for different setups and material, but I suggest you give it try. Good luck.
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That pause has made mine much better, but the videos will still go out of sync if I do a small jump or a pause. That's why I said it was partially fixed.
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I've always used a refresh rate change delay of 2.0 seconds because it seems to take a little less than that for my TV to change and start displaying the picture again. I could certainly try raising that just to see what happens, but I kind of doubt it's going to make any difference. Simple thing to try, though, that's for sure.
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Odd, since Gotham I've found A/V sync and 24p/29.9 content to be smooth and without dropped audio.
Please read the online manual (wiki) & FAQ (wiki) before posting.

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Yeah, changing the delay for the refresh rate change made no difference. Not surprised, as I couldn't really see why it would make any difference.
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Although I have no time atm for any testing or debug logs, I'd like to add my findings here for reference. I hope this is useful to anyone.

A/V desync appears to be different from file to file, with more similarities between files of the same container.

Independent of the file type, the A/V offset changes (it usually gets "better", ie. more similar between different files) when rewinding or fast forwarding by a few seconds after playback starts.

Examples:
  • MKV files usually need a different audio delay than MPEG-TS (live TV) or AVI of the same frame rate, while the difference between most MKV files of the same frame rate is usually negligible (after rewinding/fast-forwarding at least, see above)
  • On the other hand, 24p YouTube streams need about 200ms longer audio delay than non-YouTube 24p MP4 files.
As others have said already, this is XBMC specific. With other media players, the A/V delay changes by frame rate only (which I assume to be my TV's video processing delay). Only XBMC shows a random A/V delay for each file and file type, which even changes when rewinding or fast forwarding.

I don't see any temporal a/v sync fluctuations, though.

As for environment and settings, here are mine:
  • My TV doesn't report A/V delay via EDID. Its frame rate specific delays are set to the best of my knowledge via advancedsettings.xml <latency>.
  • I'm using WASAPI "best match" for audio output.
  • I'm using true full screen with "sync playback to display" set to "video clock (resample audio)" as all other settings are causing stuttering for me.
  • "Change display rate to match video" is set to "always" with overrides specified via advancedsettings.xml <adjustrefreshrate>
I'm always using the latest nightlies from the master branch, I never tried the Gotham branch.
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Do you see any a/v error or video sync error indicated on the codec screen (o-key) ?
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This has been driving me nuts from day one of XBMC, starting with Frodo & continuing thru Gotham 13.0. After a lot of experimentation, I finally found a combo that seems to work for blu ray MKV 24p playback & I'd thought I'd pass it on.

Windows 7, Intel HD graphics 9.17.10.2932, HDMI out to Denon 3310 receiver, Sharp 1080p 70"

Display resolution is set to 1920x1080, 59.97 Hz

Make sure you are NOT using a Windows AERO theme desktop.

XBMC settings:

Vertical sync =off
Use windowed fullscreen instead of true fullscreen
audio set up:
audio output device = direct sound HDMI
wasapi HDMI passthru
video playback settings:
adjust display to match video refresh rate= on stop /start, delay = 3 seconds (this is because it takes my display a few seconds to display after a resolution/ refresh rate change)
sync playback to display=on
sync method= audio clock
render method= dxva, hardware accelerated

Smooth playback on 24p material, 0% errors after about 10 seconds or so of playback, on True HD or DTS master audio HD soundracks.

Vertical sync= on also produces smooth playback with good audio sync during movie & after chapter changes. In both instances, audio errors zero out in about 8-10 seconds & maintain a solid zero.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
True fullscreen, vertical sync =on, temporal audio sync issues in True HD, waaaayy off with DTS MA, both on start up & chapter changes.

True fullscreen, vertical sync = off, smooth playback but audio takes longer to lock in on start up & after chapter change, both audio formats. Doesn't seem as locked in to me.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
If an AERO desktop is used, that's when things go wacky.

Same windowed settings as above, playing a DTS MA movie like ALIENS, frame rate is reduced drastically. Same reults with True HD like Dark Knight.

Enabling vertical sync yields same results with True HD or DTS MA.

Using True fullscreen, vertical sync on, True HD & DTS MA both lose sync after chapter change, major errors

True fullscreen, vertical sync off= stuttering playback, audio errors jumping around with True HD. loss of audio sync after chapter changes using DTS MA.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

In summary, on my system, I get the best results playing in a fullscreen window as opposed to true fullscreen, and Windows AERO desktop should be avoided.
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(2014-05-28, 19:36)FernetMenta Wrote: Do you see any a/v error or video sync error indicated on the codec screen (o-key) ?

No, sync adjusts to 0% a few seconds into playback or after seeking, no missed vblanks, nothing else appears suspicious either. It looks like everything's OK, but the audio is off by a random amount as described above.
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(2014-06-01, 08:20)Karnis Wrote: This has been driving me nuts from day one of XBMC, starting with Frodo & continuing thru Gotham 13.0. After a lot of experimentation, I finally found a combo that seems to work for blu ray MKV 24p playback & I'd thought I'd pass it on.

Windows 7, Intel HD graphics 9.17.10.2932, HDMI out to Denon 3310 receiver, Sharp 1080p 70"

Display resolution is set to 1920x1080, 59.97 Hz

Make sure you are NOT using an Windows AERO theme desktop.

XBMC settings:

Vertical sync =off
Use windowed fullscreen instead of true fullscreen
audio set up:
audio output device = direct sound HDMI
wasapi HDMI passthru
video playback settings:
adjust display to match video refresh rate= on stop /start, delay = 3 seconds (this is because it takes my display a few seconds to display after a resolution/ refresh rate change)
sync playback to display=on
sync method= audio clock
render method= dxva, hardware accelerated

Smooth playback on 24p material, 0% errors after about 10 seconds or so of playback, on True HD or DTS master audio HD soundracks.

Vertical sync= on also produces smooth playback with good audio sync during movie & after chapter changes. In both instances, audio errors zero out in about 8-10 seconds & maintain a solid zero.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
True fullscreen, vertical sync =on, temporal audio sync issues in True HD, waaaayy off with DTS MA, both on start up & chapter changes.

True fullscreen, vertical sync = off, smooth playback but audio takes longer to lock in on start up & after chapter change, both audio formats. Doesn't seem as locked in to me.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
If an AERO desktop is used, that's when things go wacky.

Same windowed settings as above, playing a DTS MA movie like ALIENS, frame rate is reduced drastically. Same reults with True HD like Dark Knight.

Enabling vertical sync yields same results with True HD or DTS MA.

Using True fullscreen, vertical sync on, True HD & DTS MA both lose sync after chapter change, major errors

True fullscreen, vertical sync off= stuttering playback, audio errors jumping around with True HD. loss of audio sync after chapter changes using DTS MA.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

In summary, on my system, I get the best results playing in a fullscreen window as opposed to true fullscreen, and Windows AREO desktop should be avoided.

Sticky this post. These settings worked great with my HD 4000. No global lipsync delay needed. Final can enjoy 24p with XBMC.
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