[Mplayer-users] Fwd: subtitles

[Arpi]

Hi,

> >I have bad subs too, with out of sync. And I think I know the problem.
> >DVD has mpeg2, usually progressive streams. its fps variables between
> >24-30 fps, depending on scene complexity etc.
> DVD has _variable framerate_? I can't believe that, televisions would 
> break in half... Where is that information from?
mpeg2 specs, decoder source etc.

i mean not exactly vbr like in mp3s. it's field repeating.
TV displays fields at 50hz (half of an 25fps interlaced frame), but in
mpeg2 you can repeat any field up to 3 times (if they are very similar)
to free some bits for other fields. and it's heavily used in some disks.

just check the frame counter in the status line and count it for example
60 secs. it won't be 60*fps in most cases!

about 10% of my VOBs uses exact constant fps, others are progressive.

another use of this when 24fps cinema film is digitalized to 30fps NTSC, then
they are repeating every 4th field, so they get 4:5 upsampling of framerate.
(it's also somehow vbr framerate, because 3 fields are at 30fps and the
4th is double long so 15fps). this results interlaced picture whan playback
on monitor (because it does not de-interlace at 30fps)
In mpeg1, divx etc you will have that double long field encoded TWICE!
mpeg2 allows to encode it once and there is a flag to mark it's double long.

> >Another question is that sub is synced to audio or video? I think that
> >frame-based subs are for video and time-based for audio. right?
> >
> >Something like +/- can be added easily, just increment/decrement the
> >sub_delay variable by for example 0.1
> >But I don't know which keys are the best for it. Any ideas?
> 
> How about < and > ? To "shift" titles back/forwards
ok, why not :)


A'rpi / Astral & ESP-team

--
mailto:arpi at thot.banki.hu
http://esp-team.scene.hu

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