No guarantee that this still works; last modified date says 2009. I used it to resize video to less than 400x704 for display on my nokia n810. You can probably play with the parameters too.

n8x0_recode.bash

#!/bin/bash

#Requires:
#  mplayer, mencoder. mkvmerge
#  libx264, liblame

HaveOpt() {
  local needle=$1
  shift
  while [[ $1 == -* ]]; do
    case "$1" in
      --) return 1;; # by convention, -- is end of options
      $needle) return 0;;
    esac
    shift
  done
  return 1
}

# This function isn't used. Honestly, I don't remember why it didn't work and why
# I didn't use `mktemp "/tmp/$(basename $0).XXXXXX.out"`, which is roughly the same thing
RandFile() {
FILE="/tmp/$(basename $0).$RANDOM.out"
while [ -e $FILE ]
do
  FILE="/tmp/$(basename $0).$RANDOM.out"
done
}

#RandFile
FILE=`mktemp`

echo Using file $FILE

# Bad sed removed due to \"; shinanigans:
#    sed -e 's/"/\\"/g' -e 's/=\(.*\)$/="\1"/'
# New sed uglier (love those backslashes), but proper.
mplayer -quiet -vo null -ao null -frames 0 -identify "$1" 2>/dev/null | grep "^ID_" | sed -e "s/'/'\\\\''/g" -e 's/=\(.*\)$/='\''\1'\''/' > $FILE
source $FILE
rm $FILE

echo "Video Width: " $ID_VIDEO_WIDTH
echo "Video Height:" $ID_VIDEO_HEIGHT

# for n8x0, 420x200 is the optimal size.
# 704x400 is the optimal size for the android device I target most recently.
TARGET_WIDTH_PIXELS=704
TARGET_HEIGHT_PIXELS=400

# This variable is only so I don't recompute the greater scaling axis for display:
AUTOSCALE_AXIS=$(bc <<< "scale=3; $ID_VIDEO_WIDTH/$TARGET_WIDTH_PIXELS - $ID_VIDEO_HEIGHT/$TARGET_HEIGHT_PIXELS")
#echo "Scaling axis (negative means Y_{new}/Y_{old} > X_{new}/X_{old}): " $AUTOSCALE_AXIS
if [[ "$AUTOSCALE_AXIS" = -* ]]; then
  #echo "Scaling to height"
  SCALE_WIDTH=-2
  SCALE_HEIGHT=$TARGET_HEIGHT_PIXELS
else
  #echo "Scaling to width"
  SCALE_WIDTH=$TARGET_WIDTH_PIXELS
  SCALE_HEIGHT=-2
fi

#RandFile

#VOUT=$FILE
VOUT=`mktemp`
echo VOUT=$VOUT

rm -f divx2pass.log

#mencoder "$1" -o $VOUT -nosound -ovc lavc -lavcopts vcodec=mpeg4:autoaspect:vbitrate=500:vpass=1 -vf scale=$SCALE_WIDTH:$SCALE_HEIGHT -ffourcc DIVX -idx
#mencoder "$1" -o $VOUT -oac copy -ovc lavc -lavcopts vcodec=mpeg4:autoaspect:vbitrate=500:vpass=2 -vf scale=$SCALE_WIDTH:$SCALE_HEIGHT -ffourcc DIVX -idx

X264_BOTHPASS_OPTS="crf=21:bframes=8:b_pyramid:8x8dct:threads=auto"
X264_FIRSTPASS="turbo=0:pass=1"
X264_SECONDPASS="pass=2"

AUDIO_FIRSTPASS=( -nosound )
AUDIO_SECONDPASS=( -oac mp3lame -lameopts br=128 )

VIDEOSCALE_OPTS=( -vf scale=$SCALE_WIDTH:$SCALE_HEIGHT )

mencoder -ni "$1" -o $VOUT "${AUDIO_FIRSTPASS[@]}" -ovc x264 -x264encopts $X264_FIRSTPASS:$X264_BOTHPASS_OPTS "${VIDEOSCALE_OPTS[@]}"
mencoder -ni "$1" -o $VOUT "${AUDIO_SECONDPASS[@]}" -ovc x264 -x264encopts $X264_SECONDPASS:$X264_BOTHPASS_OPTS "${VIDEOSCALE_OPTS[@]}"

#mencoder "$1" -o $VOUT -oac mp3lame -lameopts br=128 -ovc x264 -x264encopts qp=19:bframes=8:b_pyramid:8x8dct -vf scale=$SCALE_WIDTH:$SCALE_HEIGHT

XCODED_VID_PREFIX="nit-"

if [[ "$1" = *.mkv ]]; then
  mkvmerge -o "$XCODED_VID_PREFIX""`basename "$1" .mkv`".mkv $VOUT -A -D -B "$1"
  rm $VOUT
elif [[ "$1" = *.ogm ]]; then
  mkvmerge -o "$XCODED_VID_PREFIX""`basename "$1" .ogm`".mkv $VOUT -A -D -B "$1"
  rm $VOUT
else
  mv $VOUT "$XCODED_VID_PREFIX""`basename "$1" .avi`".avi
fi

Updated a little. Surprisingly, this still works, at least in one of my VMs. Metadata is still discarded, but the point is to save flash space. I did eventually remember why RandFile shouldn't be used; VOUT isn't properly quoted anywhere.