[MPlayer-users] scaling and deinterlacing, telecine

[Matyas Sustik]

Hi All,

After reading several tutorials on movie encoding and deinterlacing
I still have a few questions.

1. I read a comment saying that if you encode for TV then you may leave
the movie interlaced.  What does it exactly mean to encode for TV?  I have
a 1080p LCD HDTV which I am driving with a computer.  The refresh rate is
50Hz.  Does the above comment refer to my situation?  Should I prefer
interlaced or noninterlaced videos (I can decide whether I deinterlace when I
encode it so why would or wouldn't I do it?)

2. I crop the videos for encoding as recommended.  So let us say that I
end up with crop=1408:804:256:136.  Should I scale the video as part of the
encoding?  If I do not scale, then the scaling has to be done at playback
time.  Does it make better sense to scale to something of which multiple is
the screen resolution or I should not bother with that?  With a 1080p display
I could scale to: scale=-2:540 right?  Until now I did not bother scaling
for DVD-s but for OTA 1080i content I may opt for downscaling.  So as another
example: I need to crop to 1904:1072:10:0, so should I scale to 952:536 or
960:540 ?

3. A film (24fps orig) was shown OTA in 1080i.  I cannot recognize the
interlacing patterns for certain.  It looks like PPIIIIPPIIII which does not
resemble any documented pattern I found.  I was so curious as to what the
broadcaster did to this source that I asked it in email.  Here is what I got:

"Also, ALL programs on the HD channel are 1080i (interlaced).
Programs that are not true HD are upconverted to 1080i with a high
quality Snell and Wilcox upconverter."

So could someone here give any advice on how to reencode such a source?

Thanks,
Matyas
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Every hardware eventually breaks.  Every software eventually works.