Source this

rc-avi2ipad.sh

FFMPEG=/opt/ffmpeg/bin/ffmpeg

function avi2ipad() {
  for file in $*; do
    title=$(basename ${file} .avi)
    outfile=${title}.mp4
    timestamp=$(date "+%Y-%m-%d %H:%M:%S")

    if [[ -f ${file} ]]; then
      echo "[${timestamp}] Converting ${file} to ${outfile}"

      time ${FFMPEG} -y -i ${file} -f mp4 -metadata title=${title} \
          -timestamp ${timestamp} -vcodec libxvid -s 480x270 -b 1024k \
          -bufsize 2M -maxrate 1.5M -g 250 -flags +aic+cbp+mv0+mv4 \
          -trellis 1 -mbd 2 -cmp 2 -subcmp 2 -threads 0 -acodec aac \
          -ac 2 -ab 128k ${outfile}
    fi
  done
}

H264 + AAC (just as slow...)

      time ${FFMPEG} -y -i ${file} -f mp4 -metadata title=${title} \
          -timestamp ${timestamp} -vcodec libx264 -level 30 -b 1024k \
          -bt 1024k -bufsize 10M -maxrate 10M -g 250 -coder 0 \
          -flags +loop -cmp +chroma \
          -partitions +parti4x4+partp8x8+partb8x8 -flags2 +mixed_refs \
          -me_method umh -subq 6 -trellis 1 -refs 3 -me_range 16 \
          -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -qmin 10 \
          -qmax 51 -qdiff 4 -threads 0 -acodec aac -ac 2 -ab 128k \
          ${outfile}