If you want your final output to be letterboxed, I’ve found that you can copy your sequence and paste it into a standard def timeline. Then let it render out, export QT movie, then drag it into compressor. The rendering time should be a little bit longer than the length of the sequence, but for me it has the best results. Doing it this way is also faster because Compressor encodes SD a lot faster than HDV. In fact, I’ve found that HDV renders generally take longer than DVCProHD. Hope this helps. Good luck.