On Thu, Mar 29, 2007 at 09:56:17AM +0900, Phillip Gawlowski wrote:
> Trans wrote:
> >Sorry about the delayed response. I just have too much one my mind...
> >
> >On Mar 23, 8:18 am, Mauricio Fernandez <m... / acm.org> wrote:
> >
> >>Ah I see, you were surprised at deflate being so bad... I was surprised at
> >>your surprise :)
> >
> >Truly surprised. Makes me wonder why other formats like 7z aren't more
> >widely used. Is decompression speed really that much more important
> >than size?
> 
> Taking at todays cheap processing time and even cheaper mass storage, 
> I'd say, all else being equal, size isn't that important to the end user.
> 
> in other environments (transferring large files across a thin pipe), 
> size is more important than speed.

Actually, I suspect that there are a couple reasons for the greater
popularity of some compression schemes, despite their poorer compression
performance:

1. When you wish to use compression "on the fly", as it were, speed is
*very* important.  You want opening, closing, and otherwise using files
that are kept in a compressed format, to be about as quick and
responsive as using uncompressed files.  This is probably not anywhere
near as big a reason as the other one, though. . . .

2. Certain compression programs are very well known, and "everyone" has
them (for some definition of "everyone", depending on OS platform, et
cetera).  Thus, "everyone" uses them.  Short of producing a hugely
popular program that handles both old and new compression algorithms (or
both old and new file formats, in other examples of this phenomenon in
action), adoption of something new is going to be very slow and prone to
failure despite any technical advantages to the new algorithm/format.
This is illustrated by the demonstration of the commercial end-user
market failure of the Betamax -- VHS won that little skirmish simply
because it was more widely available, quickly became a household word,
and prevented migration to Betamax simply by way of market inertia.

-- 
CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ]
"A script is what you give the actors.  A program
is what you give the audience." - Larry Wall