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**Zyrex** · 2008-11-28, 03:17

I play 1080p mkv files on my HTPC (sound is digital spdif out).

When I use 60Hz the image is jittery. By setting it to 24Hz the problem is solved but then i almost always get an audio delay. I have to manually set an audio offset by 0.200s. Why? is there an better automatic solution?

(and when i try to play some normal tv ripz it is jittery @ 24Hz but good when i put it back to 60Hz, is there no way to detect this automaticly?)

mindweaver · (This post was last modified: 2008-12-01, 08:14 by mindweaver.)

I second this. 60 and 50hz running HD and SD, then the audio delay is perfect..

But when running HD material (720 alt 1080p mkv) in 24hz, I have to set -250ms audiodelay. It seems like a fixed delay for all mkv HDfiles. So I guess this is a bug that can be fixed.

mindweaver · (This post was last modified: 2008-12-04, 19:28 by mindweaver.)

It seems that you fixed it. very nice Smile

now everying I play at 24hz is synched.

My problem now is that I have found out that my TV accepts 23.98hz which is spot on the fps of HD videos. And what do you know.. now everything I play at 23.98hz is out of sync 250ms. I have to set it to -0.250 to get in sync.

EDIT: seems that this only affects 720p releases. My 1080p mkv releases seems to sync fine. Only tested on a few though.

elupus · 2008-12-05, 05:02

The problem is that when you get spot on hz, the player can not catch up at all to get to the right frame. This means it need to drop a frame todo so, currently the limit of a/v desync before we allow frames to be dropped is quite large.

The reason for this is to allow for periods of slower decoding.. But when you have your video output at same speed as the video. this doesn't work anymore.

Just a situation that didn't exist on the old xbox, thus not something we had thought of. However, since i've started playing at 24hz myself, I'll probably get annoyed with it soon enough and start looking at it Smile

mindweaver · 2008-12-05, 07:00

Ok

Thanks for the explanation Smile

**ashlar** · 2008-12-05, 10:36

elupus Wrote:However, since i've started playing at 24hz myself, I'll probably get annoyed with it soon enough and start looking at it

This is really good news. Reclock-like smoothness is now 'round the corner! Big Grin

**Zyrex** · 2008-12-05, 10:59

whats all that reclock thing ashlar? Can i make things better with reclock? And how?

**ashlar** · 2008-12-05, 11:08

Zyrex Wrote:whats all that reclock thing ashlar? Can i make things better with reclock? And how?

Definitely better, but only with DirectShow players. You can have a look here http://forum.slysoft.com/showthread.php?t=19931 bearing in mind that PAL slowdown is only one of the features of Reclock, the other being the handling of vsync correction and different clocks in your computer that need to be harmonized. If you download it there's a readme file with some information and background.

It's no help for XBMC, though.

mindweaver · 2008-12-14, 05:43

It seems not (running builds after 16501.. maybe some before) that when I start a 24p video file in 24hz or 23.98hz the audio is synched! BUT if I pause it or press step forward it goes out of sync and I have to set it back -0.200 - -0.250.

Just wanted to add some info on this Smile

dpassent · 2008-12-16, 00:08

on 16501 I noticed this today also. MKV played back at 24Hz. Weird stuff is that I didn't pause the video. Playback started in-sync and then (maybe when I was grabbing another beer) in 1/3 of the movie it desyced, had to manually adjust to -300ms and this was spot on till the end.

just my .02USD

DP

mindweaver · (This post was last modified: 2008-12-18, 12:58 by mindweaver.)

I just saw this change:

Quote:Changeset 16602:

changed: only use the explicit framedropping code when FF/RW:ing. since the demuxer framerate is not guaranteed to be correct, as in the case of 24fps material stored with pulldown flag to achieve 30fps. this functionality dropped frames when it was not needed.

Note.. This change makes any video that has a fps higher than your current display HZ play out of sync. Before it might have played abit better.

This seems to work OK when running 24fps (23.98) video on a 24hz screen. But it does not fix running 24fps video (23.98) on a 23.98hz screen.

EDIT: scratch that.. seems that setting -0.250 is still a better sync match.

mindweaver · 2009-01-18, 12:16

Long time since we posted here. I just want to know if there is any development made to try and correct this issue?

I still have to set my audio sync back -0.250 everytime I play a videofile with the same fps ans my TVs hz.

**pike** · 2009-01-18, 12:33

I have this issue on my set regardless of refresh, and it is not XBMC's fault, it's the tv set's fault, and here's why:

Modern LCD tv's do A LOT of videoprocessing before showing the result to you, this processing takes some time. This means INEVITABLY that video will come slightly later than audio does. This is why some tv's have "game mode" and similar, this is a mode with quicker processing time to reduce LAG.

The only way to fix this issue (for XBMC) is to also delay AUDIO the same amount (this won't work for gamers).

Now Im not sure this is what is happening for you, but I suspect it might be

mindweaver · 2009-01-18, 13:03

pike Wrote:I have this issue on my set regardless of refresh, and it is not XBMC's fault, it's the tv set's fault, and here's why:

Modern LCD tv's do A LOT of videoprocessing before showing the result to you, this processing takes some time. This means INEVITABLY that video will come slightly later than audio does. This is why some tv's have "game mode" and similar, this is a mode with quicker processing time to reduce LAG.

The only way to fix this issue (for XBMC) is to also delay AUDIO the same amount (this won't work for gamers).

Now Im not sure this is what is happening for you, but I suspect it might be

Hey, nope. My issue is not the same. When I set my TV to 60hz everything is in sync. It is only when I set the TV to 23.98hz or 24hz and run HD/SD material, that is 23.98/24p, I have to adjust sync -0.250.

This was written before

Quote:The problem is that when you get spot on hz, the player can not catch up at all to get to the right frame. This means it need to drop a frame todo so, currently the limit of a/v desync before we allow frames to be dropped is quite large.

The reason for this is to allow for periods of slower decoding.. But when you have your video output at same speed as the video. this doesn't work anymore.

Just a situation that didn't exist on the old xbox, thus not something we had thought of. However, since i've started playing at 24hz myself, I'll probably get annoyed with it soon enough and start looking at it

I was just wondering if you have looked into it yet. It should be a more common problem when the userbase with modern 24hz TVs grows Smile

User 34959 · 2009-01-18, 13:40

dpassent Wrote:on 16501 I noticed this today also. MKV played back at 24Hz. Weird stuff is that I didn't pause the video. Playback started in-sync and then (maybe when I was grabbing another beer) in 1/3 of the movie it desyced, had to manually adjust to -300ms and this was spot on till the end.

just my .02USD

DP

I noticed this too. It might be that pausing/rewinding video causes it to go out of sync.