23.976p -> 50hz conversion
#1
Hello,

Recently I started using XBMC and I must say that it is the best media center software I've ever used. There's one annoyance, though.

I live in a PAL country, so I guess I'm not really used to all the judder that is caused by the 3:2 pull down to get movies to display at 60hz, which is what XBMC seems to be doing on my LCD TV/monitor (which is 60Hz by default).

I'd much rather opt for a 4% speedup or better yet a 2:2:2:2:2:2:2:2:2:2:2:3 pulldown and display everything at 50Hz (or 100, but I guess that's up to my TV). Or do a relatively simple 2:2 or 3:3 pulldown if I can get my display to work at 48 or 72Hz.

My question is if it is possible to achieve any of the above possibilities using XBMC? Which of the three 'algorithms' have been implemented by XBMC? Tnx!
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#2
LB06 Wrote:Which of the three 'algorithms' have been implemented by XBMC? Tnx!
All of them, check http://wiki.xbmc.org/index.php?title=Vid...s#Playback
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#3
bobo1on1 Wrote:All of them, check http://wiki.xbmc.org/index.php?title=Vid...s#Playback
Thank you for your reply, but I don't think this is what I'm looking for. I intend to change the cadence of the video (actually, change it as little as possible) to avoid telecine judder.
The necessity to keep audio in sync may be a consequence of this action (in case of a PAL speedup, anyway), but the A/V sync itself is not part of my problem.
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#4
Adjust refreshrate setting is described there too Smile
Also sync playback to display with sync method set to resample allows for PAL speedup.
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#5
bobo1on1 Wrote:Adjust refreshrate setting is described there too Smile
Also sync playback to display with sync method set to resample allows for PAL speedup.
Ah yes I see. Let me see if I get what you're saying. If I set my LCD to output @~50Hz and I enable that setting I will achieve a 2:2 pulldown and a 4% PAL speedup? So if I have 4 frames ABC and D, it will be displayed as AABBCCDD but 4% faster @50Hz?

And if I set my LCD to output at 48 or 72Hz (rather 47.952 or 71.928 probably) will it do an even pulldown with frame repetition? I.e. AAABBBCCCDDD @72Hz?

And how can I get XBMC to do a 2:2:2:2:2:2:2:2:2:2:2:3 pulldown? I.e. AABBCCDDEE..JJKKLLL @ 50Hz?

Thanks!
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#6
XBMC doesn't do any pulldown, it just shows frames at a certain interval.
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#7
LB06 Wrote:And how can I get XBMC to do a 2:2:2:2:2:2:2:2:2:2:2:3 pulldown? I.e. AABBCCDDEE..JJKKLLL @ 50Hz?

why would you want to?:confused2:


you say you don't like 2:3 pulldown, yet you want the above (which is worse, imo, than 2:3)
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#8
Could I get a quick confirmation please. Are these the best settings to play 23.96 video on a 50hz tv.

Adjust display refresh rate to match video : Enabled

A/V sync method [Audio Clock, Video Clock(resample audio)] : Enabled
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#9
If your tv only does 50 hertz there's no need to have adjust refreshrate enabled.
Also the resample sync method doesn't work with passthrough.
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#10
Thanks for your answer bobo1on1.

My tv does have a 60hz mode but whatever I play it stays at 50hz. i.e 23.96 @ 50hz (xorg.conf problem?).

I don't use passthrough Big Grin

P.s my tv doesn't have a 24fps mode
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#11
neil.j1983 Wrote:why would you want to?:confused2:


you say you don't like 2:3 pulldown, yet you want the above (which is worse, imo, than 2:3)
I don't know. I've never seen Euro-pulldown I suppose. But it seemed like a good way to avoid 4% speedup while minimizing the judder (judder every 13th frame instead of every even (or uneven) frame). But you may be right. Maybe Euro-judder is more noticable than NTSC judder. But I'd like to see that for myself Smile

bobo1on1 Wrote:XBMC doesn't do any pulldown, it just shows frames at a certain interval.
If XBMC doesn't do pulldown, how is 23.976fps stuff displayed/outputted @60Hz? Or any other refreshrate than the actual framerate of the source for that matter?
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#12
We can't do pulldown since we output progressive frames. So what we do is just display a frame on the screen refresh that matches best in time.
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#13
So you do something like this? Suppose you have a 24fps movie and a 60Hz LCD:
Code:
Frame   01    02       03    04       05    06       07
Refresh 01-02-03-04-05-06-07-08-09-10-11-12-13-14-15-16
Representing 16/60 of a second and 7 frames displayed.

So basically A-B--C-D-- instead of AABBBCCDDD? I suppose the 'gaps' are filled in by the LCD (or rather the frame will remain on the screen during the gaps)? And how about a CRT screen (never tried it with XBMC), doesn't it cause flicker?

Also, I wasn't aware that you couldn't do pulldown on progressive frames? What about the 5:5 pulldown my TV is doing when receiving a 24Hz signal over hdmi to display it @120Hz (5:5 pulldown)?

Or am I misunderstanding something here? Anyway, I really appreciate any insight you could give me. Tnx! Smile
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