[MPlayer-dev-eng] BUG - incorrect fps detected on NTSC DVDs result in jumpy video
iive at yahoo.com
Thu Feb 21 17:49:22 CET 2002
Can you upload a sample file in 'incomming' (about 50mb)
There was explanation about bad mastering and converting that makes fields soup.
Anyway i don't have dvd and i cannot get/play dvd from your regeon.
--- Christian Lambert <clambert at sgi.com> wrote:
> |> I noticed that mplayer doesn't correctly detect NTSC DVDs video
> |> that are encoded in progressive mode (24fps) (which is the case
> |> for 90% of NTSC movies)
> |> It will play those DVDs at the normal 30 fps which result in a
> |> jumpy video especially during pan scenes or scenes with lots of
> |> motion because fields are duplicated.
> |Yes, I noticed the same with some SVCDs.
> |> The mpeg2 stream contains "repeat" flags on some fields to take
> |> the original 24fps source and play it at 30fps so mplayer should
> |> skip those repeat frames and play just the original 24
> |> progressive frames.
> |Well I think we need some logic to know which frames to skip, so we need to
> |know where the info which frames to repeat is stored in libmpeg2.
> |I guess Arpi knows better about that code, than me :)
> |Best Regards,
> | Atmos
> I know that xine and ogle already have this algorithm in it to play
> only the FILM portion of the DVD and not the extra fields that
> are just thrown in there to make it 30fps. Actually, playing it
> with 30fps is almost as bad as playing it in interlaced mode where
> you don't get the true 24 progressive images. I see that this bug
> is still not fixed in the latest CVS I just pulled.
> I'm not really a programmer but I know how to read source code, so I
> started looking at the code but I can't figure out where the bug
> could be coming from since there are calls to libdvdread involved here too.
> I think that the framerate code is in the header of the VOB and it
> has a special mark when the DVD is encoded progressive (24fps) versus
> interlaced (29fps). I think what's happening is that when you play
> a PAL movie, you don't really notice this because there is only two
> field duplicated to make it 25fps. However in the NTSC world, it's
> a greater problem because we have to duplicate lots of fields to convert
> from 24 to 30fps on the fly, which is where those "rff" flags comes into
> play to say which field to repeat in the mpeg2 video.
> Since 99% of the NTSC movies are encoded in progressive mode, I'm seeing
> this on all my DVDs. Altough maybe not everyone notices it, if you pay
> close attention you really see the duplicated frames in a slow camera pan scene.
> That's the only real bug that's preventing me right now from watching
> DVDs in mplayer with nice and smooth playback.
> If nobody has the time to look at this, could you at least let me know
> all the relevant source file that I should check regarding this bug.
> MPlayer-dev-eng mailing list
> MPlayer-dev-eng at mplayerhq.hu
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