Here are the benchmarks I have so far:
TDM's provided mencoder binary
$ time /Applications/TiVoDecode\ Manager.app/Contents/Resources/mencoder -af volume=13:1 -of lavf -lavfopts i_certify_that_my_video_stream_does_not_use_b_frames -demuxer lavf -lavfdopts probesize=128 -oac lavc -ovc lavc -lavcopts keyint=15:aglobal=1:vglobal=1:coder=1:vcodec=mpeg4:acodec=aac:vbitrate=1800:abitrate=128 -vf pp=lb,scale=640:480,harddup -o ~/Desktop/clip.tdm.mp4 ~/Desktop/clip.mpg
real 1m9.518s
user 1m7.768s
sys 0m0.847s
Mac Intel-optimized mencoder binary
$ time ./mencoder -af volume=13:1 -of lavf -lavfopts i_certify_that_my_video_stream_does_not_use_b_frames -demuxer lavf -lavfdopts probesize=128 -oac lavc -ovc lavc -lavcopts keyint=15:aglobal=1:vglobal=1:coder=1:vcodec=mpeg4:acodec=aac:vbitrate=1800:abitrate=128 -vf pp=lb,scale=640:480,harddup -o ~/Desktop/clip.custom.mp4 ~/Desktop/clip.mpg
real 0m29.061s
user 0m27.210s
sys 0m0.743s
and here are the file sizes
$ ls -ltr clip.*
-rw-r--r-- 1 xxx xxx 12654193 Mar 22 01:59 clip.mpg
-rw-r--r-- 1 xxx xxx 20839638 Mar 23 01:50 clip.tdm.mp4
-rw-r--r-- 1 xxx xxx 20859165 Mar 23 01:51 clip.custom.mp4
and just for fun, I lowered the bitrate down to 600kbs so that it actually does compression and here are the times and filesizes.
TDM:
real 1m7.573s
user 0m59.340s
sys 0m0.904s
Intel-optimized
real 0m31.287s
user 0m25.143s
sys 0m0.787s
$ ls -ltr clip*
-rw-r--r-- 1 xxx xxx 12654193 Mar 22 01:59 clip.mpg
-rw-r--r-- 1 xxx xxx 8135459 Mar 23 02:26 clip.custom.mp4
-rw-r--r-- 1 xxx xxx 8131077 Mar 23 02:27 clip.tdm.mp4
And well if you've managed to wade through all that I guess I'll leave you with some installation instructions for the mencoder binary.
1. Download
2. Backup old mencoder binary
mv /Applications/TiVoDecode\ Manager.app/Contents/Resources/mencoder /Applications/TiVoDecode\ Manager.app/Contents/Resources/mencoder.old
3. Copy in new mencoder binary
cp mencoder /Applications/TiVoDecode\ Manager.app/Contents/Resources/mencoder
4. Enjoy (Did I mention this probably only works for the Core2Duo??)
5. Digg this