AcidRip hasn't been updated in a long time.  In fact, I'm not even sure anyone is maintaining it anymore.  But I still use it quite a bit.  Today I noticed, after an yum update for f10, that the previews just wouldn't work anymore.  So I looked at the debug window and found this was the line it was trying to run:

mplayer -vo gl2 -ao sdl  dvd://1 -dvd-device /dev/sr0 -alang English -chapter 3-3 -frames 10 -sstep 5 -nocache -vf crop=0:0:0:0,scale=261:-2 -wid 67109117

Running mplayer with the -vo and -ao options is something I configured in the Settings tab of acidrip.  These are required to get proper video and audio output with mplayer on my system.  I'm no mplayer expert but a little trial and error uncovered that the problem with this command comes from the -frames and -sstep options.  If I remove them then the video and audio previews play just fine with mplayer.  So I dug into the AcidRip code and found that in acidrip.pm, lines 323-326 look like this:

my $frames = $::settings->{‘ppc_bug'} ? 100 : 10;
my $sstep = “-sstep ” . int $length / ( 3 * $frames ) + 1;
$sstep = “-ss ” . int $length / 3 if $::settings->{‘ppc_bug'};
$menc{‘frames'} = “-frames $frames $sstep”;

Commenting out that last line and replacing it with the following line fixes the preview problems I've having with AcidRip.

$menc{‘frames'} = “”;

These options supposedly only cause the preview to play a little faster and skip a little into the specified track.  But they both have to come out to get the previews to work properly on my system.

Your mileage may vary.

Another thing I discovered after the yum update is that mencoder was no longer compiled with lame support for audio.  I'm not sure why that change has occurred (maybe it was just a bad rebuild of mencoder?) but the solution from AcidRip's point of view is to simply change the audio to twolame.  Rips appear to work fine with that.