[MPlayer-users] will mplayer do a 3:2 pulldown on 24 fps video when ofps=29.97?

D Richard Felker III dalias at aerifal.cx
Fri Feb 21 00:04:17 CET 2003

On Thu, Feb 20, 2003 at 05:40:38PM -0500, mplayer at interlinx.bc.ca wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]

> On Thu, Feb 20, 2003 at 02:03:19PM -0800, Brian Craft wrote:
> > 
> > Check CVS. I believe I saw some code for that.
> Cool.  It was in the last 2 or three VFs added.  Is it a true 3:2
> pulldown, or just a duplication of 1 in 4 frames?  If you don't know,
> no matter, I will go look at the source.

True 3:2 pulldown. Duplication would be totally pointless since you'd
get that effect automatically with mplayer using no special options.

> > I don't think detection is a problem.
> No, indeed it's not.  It's just a comparison between the fps of the
> video material and what the user has requested the ofps be.  That is
> why I suggested a nice mnemonic to make it explicit that 3:2 pulldown
> should be used for 24 frames/s material rather than some mathematical
> based frame repeat rate (i.e. repeat 1 out of 4 frames).

Telecine (3:2 pulldown) is total nonsense unless the display device is
interlaced! And even then it's ugly, IMO.

> On Thu, Feb 20, 2003 at 05:21:30PM -0500, D Richard Felker III wrote:
> > 
> > It will not be automatic, since 99% of users do not want this
> > ugliness.
> No?  It's what they are used to when converting 24 frames/s -> 59.94
> fields/s.

Most people aren't doing that. They're displaying 24 fps progressive
movies on progressive monitors. If mplayer automatically did some
telecine/interlacing crap to movies, it would be VERY annoying!

> > MPlayer does
> > not officially support increasing the fps, but if you're using a -vo
> > driver with vsync support (mga_vid) or DVB output,
> I am.  dfbmga.  I don't think any patches have been sent to to support
> this, because to do it effectively you have to display and wait for
> vsync in a separate thread (or starve the demuxer/decoder thread) and
> we all know what A'rpi thinks of threads.  In fact I have been meaning
> to bring up this issue here for a while.  Maybe my next message...
> :-)

It has nothing to do with threads. Switching page at vblank is the
responsibility of the video driver; however, most of them suck too
much to do this. :( mga_vid will do it, and there's an api in the
linux fbdev layer for "wait to apply these changes until vblank", but
none of the fb drivers implement it. :(

> > Eventually, mplayer probably will have a -ofps option like you
> > describe. This will make it work with all -vo's, but you'll still need
> > -vop telecine if you want telecine output.
> The only problem I have with having to specify -vop telecine is that
> I have to select when to use it depending on whether the video
> material is 24 frames/s or not.  This sucks when you are using MPlayer
> in a PVR like project where material can be both 24 frames/s and 59.94
> fields/s.  If -vop telecine was smart enough to step out of the way
> when it's not needed (source material is already 59.94 fields/s) that
> would be fine though.

Video filters can't tell what the framerate is, and anyway, it's
possible someone might want to use 3:2 pulldown for any 20% framerate
increase, not just 23.976->29.97.

For a PVR, you really should run mplayer -info or whatever in advance
to get the stream parameters, then use these to configure the second
run. There are plenty of other things like size/scaling you need to
handle already I'm sure...


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