field order mysteriously changing (was: Re: [MEncoder-users] Trouble transcoding 1080i "video" to NTSC DVD -- SOLVED! )

[Dieter]

> > I'm having trouble transcoding 1080i HD "video" (interlaced) content
> > from my Tivo HR10-250 to "standard" NTSC DVD.  The video source is a
> > live hockey game.  [...snip...]

> The two remaining problems I had were: (1) Field order
> mysteriously changing in original HD source;

> For
> each of these smaller files, I manually determined the field order by
> examining the clip in DGIndex, and, if necessary, added the 'phase=t'
> filter to change to "top-field first".

Do you think the broadcaster was randomly changing the field order?
Or Tivo?  Perhaps different cameras had different field order?
Or something else ???

Does Tivo play it okay?  If so, is Tivo detecting the field order changes
and fixing it automagically?  If so, could tools like mencoder, ffmpeg,
etc. be taught to fix field order automagically?