Is it possible to store about 20 000 characters in QR code? (Or even more? http://blog.qr4.nl/page/QR-Code-Data-Capacity.aspx)
I would like to store only ascii simbols (chars and numbers with extra dash and so on).
As far as I know it's possible to compress not complext text with ratio 80-98% which sound promissing: http://www.maximumcompression.com/index.html
Do you have some more experience? Thanks for sharing!
QR codes have a special encoding mode for alphanumeric data (upper-case only, plus digits and a few symbols). It uses less than 8 bits per character and can store 4,296 characters at most in this mode.
This ought to be close to optimal. For simpler data (like, all alpha), a compression algorithm like gzip might be able to achieve fewer bits per byte. Of course, no standard reader would interpret the gzipped payload as such. Only a special reader would be able to.
Can you get 5x more data into a QR code this way? No, almost surely not, unless it's a trivial case like 20,000 "a"s.
Even if you could, it would create a large complex QR code. Anything holding over a few hundred bytes gets hard to scan in practice. Version 40, the largest, is useless in the real world. Even version 20 is.