ffdshow, XviD, (interlaced) field order

[Hylas]

Hello, I have a few questions concerning the field order (top field first, bottom field first) in interlaced encoding.

1. Is there a bug in older ffdshow-builds (including the latest official version from 2004-10-12), that forces the decoder to use tff regardless of the information stored in the Mpeg4-video-stream (e.g. with MPEG4Modifier) and the swap field setting in the deinterlacing option?
This seems to be fixed in celticdruid's compile from 2005-04-06.

2. Can the field order attribute be set in XviD respectively ffdvfw/ffdshow-vfw/ffdshowenc or is it hardcoded as bff?
For XviD the answer was no (http://forum.doom9.org/showthread.php?s=&threadid=67782#post419836), but that appears to have changed (http://forum.doom9.org/showthread.php?s=&threadid=85287#post569208) in the meantime.
What about ffdshowenc?

3. Is it possible to change the field order in a faster way than with MPEG4Modifier, i.e. without rewriting the whole file?

[Hylas]

Answering some questions myself:

XviD can indeed set the field order in newer builds. From the changelog:
2004-07-11 10:34:56 GMT patch-42

Summary:
Added top field control to vfw.
Revision:
xvidcore--head--0.0--patch-42

From koepi:
* added top field first flag to vfw.

modified files:
vfw/src/codec.c vfw/src/config.c vfw/src/config.h
vfw/src/resource.h vfw/src/resource.rc


Regarding ffdshow, it seems that something has been changed in January (http://cvs.sourceforge.net/viewcvs.py/ffdshow/ffdshow/src/imgFilters/TimgFilterDScalerDeinterlace.cpp?r1=1.41&r2=1.42), and that could have fixed the swap fields behaviour. Could a developer or someone with more insight than me confirm this? :)