[vlc-devel] Video filter useful for transcoding PAL DV

Paul Corke paul.corke at datatote.co.uk
Tue Apr 17 19:02:24 CEST 2007


This filter is useful when transcoding from a PAL DV source to an
interlaced format and subsequently displaying it with a deinterlacer
such
as "bob" or "linear".  PAL DV has the field order backwards which causes
the deinterlacer to display the second frame before the first which
leads
to a juddering of the picture.  This filter moves the entire image up by
one row which corrects the field order.

There is an optional smoothing that can be used to reduce the flicker
that
occurs with bob deinterlacing however this results in some motion blur
on
the resulting image.

Sample use:

dvgrab - | vlc -
--sout'#transcode{vcodec=mp2v,vb=6000,acodec=mp2a,ab=192,\
vfilter=swapfields{deflicker=1}}:standard{access=file,mux=ps,dst=video.p
s}'

The swapfields.c goes in modules/video_filter/ and the framework code
in it is based on invert.c and sharpen.c.  Note that to get the
"vfilter"
parameter to have any effect, you need to apply the patch I sent in
earlier as well.  I have altered configure.ac so that this module is
enabled if you have dv support (--enable-dv).

Paul.
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