Interlace encoding-filed or frame based?

[gamaD]

I read the thread about interlace, cartoon, etc. I couldn't make out if xvids interlaced encoding works field-based or frame-based?

[minolta]

you feed the encoder interlaced-frames. does this answer your question? also:
-field-order (tff/bff) not important for encoding (only decoding)
-frame is encoded with "field dct" macroblocks
-encoder can switch to different macroblocks if more efficient

the way one encodes interlace with mpeg4 is not much different then mpeg2...

-Minolta