View Full Version : ePub compression


gonzule
10-25-2008, 11:33 AM
Hi,

I know that the ePub format is just a bunch of zipped files that belong to the book. I just wanted to know how compressed this files are in .zip . Can I compress them a lot to save space ir they'll be unreadable by the device ?(for me its a sony reader 505)

thank you

DaleDe
10-25-2008, 11:44 AM
Hi,

I know that the ePub format is just a bunch of zipped files that belong to the book. I just wanted to know how compressed this files are in .zip . Can I compress them a lot to save space ir they'll be unreadable by the device ?(for me its a sony reader 505)

thank you

With the exception of the mime-type all of the files are compressed using zip standard compression generally. Of course images are often already compressed so the difference isn't high but the text is compressed a lot. You can try a higher compression number if you wish and the zip you use supports it but don't expect to save a lot.

Dale

gonzule
10-25-2008, 12:50 PM
yeah, i know you dont save A LOT, but i was trying do put wikipedia on the sony reader, so if i save 10 KB for each file having a count of 1,000,000 files, it really makes a difference.

thanks for the info

wallcraft
10-25-2008, 04:35 PM
See Explode and Implode an ePub? (http://www.mobileread.com/forums/showthread.php?t=29057), where it was rightly pointed out that it isn't clear why an ePub reader would care much about the ZIP details. But in fact they do - see DE upgrade ePub problems, #21 (http://www.mobileread.com/forums/showpost.php?p=262099&postcount=21). There may be room for extra computer processing to get better compression, but the compression format must be the ZIP standard and the file mimetype must be first and must not be compressed.