NTSC <-> PAL framerate conversions
#1
hi all,

we probably all know that ntsc encoded movies are choppy when viewed on a pal box and vice versa
problem is that ntsc movies are encoded in framerates like 23.97fps or 29.978 fps while pal is 25.0 fps
this means that frames must be skipped/duplicated which results in choppy/jerky playback

however, what if we play a movie faster/slower to match the 25.0fps

take for example a 23.97fps movie. if we play this 25/23.97 times faster then normal, so at 1.0429x then its excactly 25.0 fps and should play perfectly smooth.
same for 29.97fps if we play that 25/29.97 at 0.83394x its 25.0 fps

sure the movie plays back a bit faster or slower, but would anybody notice this? i dont think so

anyway let me know your thoughts about this
if more ppl think this is a nice idea i can implement it in xbmc
frodo


frodo
XBMC Project Founder (Retired), now head programmer of MediaPortal
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#2
could this be made optional so we can play around with both modes to compare them?
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#3
(frodo @ dec. 29 2003,15:28 Wrote:however, what if we play a movie faster/slower to match the 25.0fps

take for example a 23.97fps movie. if we play this 25/23.97 times faster then normal, so at 1.0429x then its excactly 25.0 fps and should play perfectly smooth.
hehe. should work. the japanese have this system in some dvd players. but not to get around the ntsc/pal issue. just to save time. :d

so how can millions o japanese be wrong Smile go for it!
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#4
what about the audio stream?
isn't that going to get out of sync?
greets,

zilvershadow
designer of the kmlbrowser script.
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#5
i added the option to xbmc
you can disable/enable it under settings->screen with the
'adj. framerate' button

(remember you gotta restart the movie b4 when changing this setting)

i tried several 23.97fps movies on my pal box and with this option enabled they play much smoother then before.

the movie plays a bit faster then normal (1.042x),
but i dont notice it.

frodo
XBMC Project Founder (Retired), now head programmer of MediaPortal
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#6
dont forget to disable pal60;-)

frodo
XBMC Project Founder (Retired), now head programmer of MediaPortal
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#7
whats the harm in adding it if it can be disabled. personally, i would prefer to user this option, hey with the movie playing faster it give me more time for other stuff:-)
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#8
i would like to suggest this behavior:

when attempting to play 29,97 fps movie on an 25fps system player should say:

---------------------------
you are about to play an ntsc (xx.xfps) movie in pal (25fps) mode would you like to:

a - play as usual (leave me alone)
x - switch to ntsc mode
y - play this movie at ntsc speed in pal mode.
---------------------------

this would make "everybody" happy- of course - this dialog box should also handle user playing pal on ntsc system.
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#9
alcapone,

i think the current way is fine. having an extra popup is a pain. i would just like to click on a movie and have it play right away.

why would you decide that some should be left alone and some should not be? i think most people would be comfortable with the current way of setting the option.

just my 2 cents.

ts
42.7% of all statistics are made up on the spot

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Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
For troubleshooting and bug reporting please make sure you read this first.
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#10
Thumbs Up 
this indeed works mighty fine.
super smooth playback. Image
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#11
btw: what version are you testing ?
the most recent i found was "xbox_media_center_2003-12-11_build-ind" (cvs)
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#12
i'm always reffering to the latest source
which i compile myself.

frodo
XBMC Project Founder (Retired), now head programmer of MediaPortal
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#13
then i must wait will some nice person compile & publish it Smile

hint hint Smile
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#14
this is a very cool feature, and works brilliantly.
the pitch of the audio is also increased slightly when speeding up the video (which is also the case for most pal dvds , most people don't tend to notice though). so if there's a us tv series or something that you watch regularly on xbmc don't be surprised if you notice the character's voices are now a bit higher with this option enabled. Smile
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#15
scary, i asked this very question weeks ago on xbox-scene and got no replies. damn i wish i'd known to come here Smile

cheers to whoever did the fix.

alex
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