Use vobcopy instead of mplayer to dump a DVD. MPlayer has to demux the audio and dump the output, while vobcopy just copies the data stream directly.
Proper syntax to get a DVD:
vobcopy -l -i /dev/dvd -t movie_name
Trace: • mkvmerge • ponymath • mencoder • trayopen • matroska • cdrecord • dvd_copy • blu-ray • ps_vita • vobcopy