Reencode .VOB files from an old DVD to .mp4 files of reasonable size

vob-to-mp4.sh

# Based on the two-pass suggestions here: https://trac.ffmpeg.org/wiki/Encode/H.264
#
# Optional: for multiple VOB files you wish to concatenate, do so *before* reencoding:

ffmpeg -i "concat:VTS_01_1.VOB|VTS_01_2.VOB|VTS_01_3.VOB" -c copy CONCAT.VOB

# The target average bitrate (for -b:v switch) is calculated like so:
#   For a video that's 600 seconds long and a target filesize of 200MB
#   (200 MiB * 8192 [converts MiB to kBit]) / 600 seconds = ~2730 kBit/s total bitrate
#   2730 - 128 kBit/s (desired audio bitrate) = 2602 kBit/s video bitrate
#
# Options are as follows:
#   -preset slow # not actually slow with a half-way decent CPU; trades speed for smaller output size
#   -b:v 2500k # see calculation above
#   -profile:v high -level 4.2 # don't care about old playback device compatibility
#   -tune film # use "grain" if grain preservation is important, "animation" if animated
#   -filter:v yadif # deinterlace filter (probably needed for old DVD sources)
#   -c:a aac -b:a 128k # 128k AAC audio (fine for lossy transfers of old DVDs)
#   -f mp4 /dev/null # use mp4 as output format but don't write a file for the first pass

ffmpeg -y -i VTS_01_2.VOB -c:v libx264 \
  -preset slow \
  -b:v 2100k \
  -profile:v high -level 4.2 \
  -tune film \
  -filter:v yadif \
  -pass 1 \
  -c:a aac -b:a 128k \
  -f mp4 /dev/null && \
ffmpeg -i VTS_01_2.VOB -c:v libx264 \
  -preset slow \
  -b:v 2100k \
  -profile:v high -level 4.2 \
  -tune film \
  -filter:v yadif \
  -pass 2 \
  -c:a aac -b:a 128k \
  VTS_01_2.mp4