On Friday 01 August 2003 04:34 am, Gordan wrote: > > This means, that if we assume this compression ratio, on a hypothetical > > size index, Bzip will result in enough improvement to move to the next > > power of 2 size 3/8ths of the time. Bottom line: On Freesites that are > > using HTML containers that have between 4KB and 4MB of uncompressed > > content, Bzips will only use 80% of bandwidth than zips. Please bare in > > mind that Zips are already reducing this bandwidth to about 23% of what > > it once was, and that space wise, this is a small part of Freenet's > > content. > > Moving down to the next power of two yields 50% reduction in space. There > is no inbetween. So, if bzip2 is 20% smaller than zip on average, given the > powers of 2 distribution of file sizes, how often will that yield that 50% > improvement?
Bzip results in going down a notch 3/8ths of the time. > > Is is taking this number down to 19% worth all the extra effort it would > > take? > > It depends on how often that would result in reducing the space usage by a > notch. And I am not all that concerned that the effort required to use one > compression library instead of another is that great. No, you missunderstand. The average bandwidth used (assuming random sized uncompressed files) after counting with Bzip is 19% of what it would be uncompressed. This is taking into account the probability that we are going down a notch. > > When you consider just how much better things are with compression, > > I think the most important thing that can be done is to insure that > > everything that is not already compressed, that is inserted, gets > > compressed. > > I completely agree there. I don't think there is any question about whether > some compression will be implemented. It is purely a question of which > algorithm/library will be used. To clarify things, I arrived at my numbers by taking a hypothetical size index between 1 and 2 units. For the values between 1 and 1 + 1/8 zips would compress the file into a file of size .25 and above that could go to size .5. For Bzips, anything below 1.5 would go to .25 and everything above would go to .5. So, assuming random samples: Bzip results in one notch improvement 3/8Th's of the time. Zips will use ~23% the bandwidth of uncompressed files, and bzips use 18.75% as much. (or 80% as much as the zips.) _______________________________________________ devl mailing list [EMAIL PROTECTED] http://hawk.freenetproject.org:8080/cgi-bin/mailman/listinfo/devl
