[libdv-dev] Possible bug encoding interlaced material?

[Jonathan W. <jw...@ph...>]

Hi all

Over the past few months I've been trying to track down the source of
flickering during horizontal movement in DVDs I've been making.  The
details of all the tests I've done and the results are available for
viewing at

  http://www.atrad.com.au/~jwoithe/mpeg/

Initially I thought the problem was with mpeg2enc (from mjpegtools). 
However, of particular interest are the last round of tests at

  http://www.atrad.com.au/~jwoithe/mpeg/pantest/

These tests seem to suggest that the root cause of the problem actually lies
in libdv's encoder.  It appears that when presented interlaced input, libdv
doesn't do the right thing, and perhaps even assumes the input is
non-interlaced: each field of the encoded frame contains blocky shadows of
the contents of the frame's other field.

A very brief glance at the libdv (and the included encodedv) source didn't
turn up any obvious way to specify whether the input was interlaced or not.
I don't know if this is an issue, but it's not at all obvious to me how
libdv can know whether the frames being presented to it are interlaced 
or not.

Anyway, what do others think?  Is this an issue?  Is there a way to get
around it so interlaced material is encoded correctly to DV by libdv?  While
having encodedv work correctly would be good, a general libdv solution is
the most important consideration from my point of view since it would mean
that the output from programs which use libdv (such as cinelerra) would be
correct.

Best regards
  jonathan