[dvd::rip] Grabbing preview image hangs

[Matthew Nagi <turbobuddhist@xxxxxxxxx>]

This happens any time dvd::rip tries to grab a preview image, either 
after ripping or when I manually tell it to.

My CPU usage goes up to 100% for about 10 to 15 minutes, then dvd::rip 
gives the error 'transcode can't find this frame.  Try forcing slow 
frame grabbing.'  I've tried to get the preview image grabbing to work 
using all combinations of the following:

dvd::rip v0.52.7 and v0.97.10
transcode v0.6.14 and v1.0.2
with slow frame grabbing checked as well as without it being checked

I'm running Gentoo.

Not sure what other package versions you might need.