Dv to mpeg2 - technical question

When converting from DV format to MPEG 2, is it
possible to utilize the undecoded frames within
the DV-format AVI file, and take them as the
I-frames in the mpeg2 file, and then create the
P and B frames from the DV frames without
first decoding the DV format?

This may seem complicated, but, the idea I am
wondering about is being able to avoid decoding
each DV frame if that format is already compatable
with the I-frame format of a standart MPEG2 file.

The alternative is to first decode each DV frame
from the avi file, then recode them to I-frames,
and then derive the P and B frames from the
I-frames. If the I-frames and the original DV
frames are not sufficiently similar in thier
coding technique (huffman), then that explains
the lengthy DV to MPEG2 process.

If anyone know the detials, please elaborate.