[FFmpeg-user] Looking for suggestions for backing up my DVDs

[Francesco Turco]

I'd like to rip my DVDs and copy them to my hard disks for backup
purposes. I'm currently doing this with a combination of mplayer and
ffmpeg. Let me explain what I managed to accomplish so far.

First step, from DVD to VOB.

$ mplayer -dvd-device /dev/sr0 -dumpstream -dumpfile Alien.vob dvd://1

Second step, from VOB to WebM/VP9/Opus:

$ ffmpeg -i Alien.vob -map 0:0 -map 0:2 -map 0:3 -c:v libvpx-vp9 -c:a
libopus -f webm -b:v 1000k -b:a 64k -ac 2 -metadata:s:a:0 language=ita
-metadata:s:a:1 language=eng -metadata title=Alien Alien.webm

Where:
- 0:0 is the video track
- 0:2 is the Italian AC-3 5.1 audio track
- 0:3 is the English AC-3 5.1 audio track

Original VOB file is 5165 MiB in size. Output WebM file is 475 MiB in
size. Less than 10 % of that.

Is this configuration good enough or there's room for improvements?

Even if I specified 1000k as the video bitrate the resulting webm file
has an overall bitrate of 593k. How can that be possible? Which bitrate
should I use for DVD-quality material?

Should I use two-pass encoding instead for better quality? Would that
take much longer?

I'm downmixing audio tracks to stereo because I don't have 5.1 speakers
and don't plan to buy them anytime soon. Is 64k enough for a stereo Opus
audio track?

Thanks.