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Note that fountain codes are very, very patent-protected by Luby et al. Five years ago I came across literature on rateless codes, which are digital fountain codes that allow practically infinite encoding, or a practically infinite stream of data from which the original could be reconstructed. One really promising type of rateless code was online codes, which required O(1) time to generate a single block and O(n) time to decode a message of length n, which was much better than the LT rateless codes that came before it. (The paper can be found at http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.12....)

I wrote up a Java implementation in my free time, and it worked well and was quite fast. I pinged the authors of the paper, asking if I could open-source it, because I came across a web site with their names on it that seemed like they were going to commercialize the idea. They replied that they had abandoned the idea of online codes because, even though their approach was faster than all other coding schemes, it still violated patents held by Luby and his company Digital Fountain, which has since been acquired by Qualcomm. That was a bummer, because I thought the online codes paper was very elegant, and the implementation was quite simple.



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