Stuttering sound from *some* Blu-Rays on Linux

[ggking7]

I'm running Gentoo Linux and Talladega Nights plays back perfectly via mplayer, but House of Wax and Italy Revealed both have stuttering sound. I've tried playing from the disc and from the hard drive. What could be the problem?

Edit: All 3 of those Blu-Rays have different video codecs, but the audio looks like same via ffmpeg -i. Could I have a performance problem with an AMD X2 4000+, 2GB RAM, and a Geforce 6200?

[nm]

All 3 of those Blu-Rays have different video codecs, but the audio looks like same via ffmpeg -i. Could I have a performance problem with an AMD X2 4000+, 2GB RAM, and a Geforce 6200?
Performance problems are quite likely, especially if the video is H.264 and you haven't built MPlayer with the multithreaded libav* libraries from ffmpeg-mt (http://gitorious.org/projects/ffmpeg/repos/ffmpeg-mt). What kind of CPU load (per core) do you get while playing the movies?

[ggking7]

I just tried overclocking my 2.1ghz CPU to 2.5ghz and it's a big improvement although still problematic. I guess that means it's performance although 'top' shows my CPU is around 50% idle while playing a video. I don't understand that.

I'm running the latest mplayer and ffmpeg from svn or git. Does that mean I'm doing what you suggest there?

[nm]

I just tried overclocking my 2.1ghz CPU to 2.5ghz and it's a big improvement although still problematic. I guess that means it's performance although 'top' shows my CPU is around 50% idle while playing a video. I don't understand that.
50% idle on a dual core can mean that one CPU is fully loaded (and probably does in your case).

I'm running the latest mplayer and ffmpeg from svn or git. Does that mean I'm doing what you suggest there?
Nope, you would need to download ffmpeg-mt from its git repository and replace the libavcodec, libavutil and libavformat directories in MPlayer's source tree by those from ffmpeg-mt. Then rebuild MPlayer.

To actually use multithreading, run mplayer with -lavdopts threads=2
This may help with your current MPlayer build too, but it won't work for all H.264 videos.