How can I start from a DVD (or .iso or VIDEO_TS directory), extract the main title, preserve the audio (AC3 5.1) and video quality/aspect ratio AND burn in a subtitle track to an mpeg2 file using mplayer/mencoder?

Currently I use mplayer to extract the main title from a dvd like this:

Code:
mplayer dvd://1 -dumpstream -dumpfile movie.mpg
Usually, this works fine for what I need (transfer to TiVo), UNLESS the DVD contains a foreign language with subtitles. So... how can I do the same thing except burn in a specific subtitle track?

I've tried variations of something like this:

Code:
mencoder dvd://1 -sid 2 -aid 128 -of mpeg -ovc lavc -oac lavc -lavcopts vcodec=mpeg2video:vbitrate=6842:aspect=16/9:acodec=ac3:abitrate=448 -channels 6 -o movie.mpg
And that mostly works, except the video quality is degraded... I'm guessing because the video bitrate isn't high enough. In the example above, I specified a video bitrate of 6842, but the resulting bitrate (according to ffmpeg) was only 2304.

How can increase the video bitrate? or is that really the reason the video quality isn't quite as good as the video extracted with -dumpstream?