Factors affecting compression savings with hdiutil

FROM : Jeremy Dronfield
DATE : Sun Dec 05 23:07:39 2004

Are there any factors (beside disk content) affecting the amount of
compression gained with hdiutil convert? I have a dmg which, when
converted yesterday, produced a 97 per cent reduction but today gets
only 92.3 percent. The contents have changed in size, but only by 8 K.
The content isn't different in nature, only slightly different in size.
The size of the compressed dmg has jumped from 456 K to 812 K.

All I'm doing is hdiutil convert -format UDCO mydmg.dmg -o
mycompresseddmg.dmg
(I've also tried the syntax given in the manpage, which is hdiutil
convert mydmg.dmg -format UDCO -o mycompresseddmg.dmg, but it doesn't
make any difference.)

If there are other factors affecting the amount of compression, could
someone give me some tips on getting the best out of conversion? I
can't find any clues in the manpage.

Regards,
Jeremy