‐
Preprocessing
is
critical
for
web
video,
but
generally
it
is
not
needed
when
you
convert
to
video
formats
like
MPEG
‐
2
for
DVD
or
SVCD.
Deinterlacing
video
‐
The
most
basic
and
critical
form
of
preprocessing
for
the
web
is
deinterlacing.
‐
Most
video
is
produced
and
edited
as
interlaced
(although,
an
increasing
amount
is
done
as
progressive
scan).
But
almost
all
web
video
is
encoded
as
progressive
scan.
‐
If
the
source
frame
of
video
is
left
with
interlaced
lines
intact,
the
output
shows
the
stacked
lines.
‐
So,
at
the
same
bit
rate,
deinterlaced
video
shows
fewer
artifacts
than
interlaced
video.
Understanding
telecine
and
inverse
telecine
‐
A
special
case
of
progressive
scan
is
film
source
and
film
‐
like
24P
production.
–
Traditional
motion
picture
film
runs
at
exactly
24
frames
per
second
(fps)
progressive
scan,
which
doesn’t
convert
to
the
59.94
fps
of
NTSC
or
the
50
fps
of
PAL.
‐
Converting
from
film
to
PAL
is
easy.
The
video
is
sped
up
4%
to
25
fps
and
converted
into
progressive
PAL.
‐
NTSC
is
a
little
more
complex
to
perform.
The
film
is
first
slowed
down
to
23.976
fps,
and
then
it
is
converted
to
the
59.94
fps
by
using
3:2
pulldown.
‐
The
first
frame
of
film
becomes
three
fields
of
video,
and
the
next
frame
becomes
two
fields
of
video,
and
the
next
becomes
three
fields,
and
so
on.
‐
This
process
results
in
two
out
of
five
frames
having
fields
that
come
from
different
source
frames.
‐
When
possible,
it
is
best
to
convert
to
24P
on
import
and
then
do
all
the
work
on
the
project
in
24P
mode.
Cropping
‐
The
safe
areas
exclude
the
edges
of
the
screen,
which
may
be
cut
off
or
distorted
on
some
televisions
(especially
older
ones).
‐
In
some
digital
video
editing
applications,
you
can
crop
an
image
using
a
filter.
In
others,
such
as
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