It is intuitively much easier, and FUD-resistant, to “add only royalty-free bricks to a royalty-free foundation”, particularly in domains that have evolved over decades and already have developed multiple solutions and algorithms. Royalty-free oriented standards groups recognize this, as do product developers in patent-oriented domains.

Expired patents, public domain technologies, known prior art are some starting points.

Similarly forward error correction techniques long predated MPEG: see http://en.wikipedia.org/wiki/Forward_error_correction for a few citations.

MPEG Systems patent 5,457,701, http://www.mpegla.com/m2s/m2s-patentlist.cfm, recognizes this and states “Description of the Prior Art …. Essentially, a forward error correction code is appended to each packet”. Perhaps this may provide insight into why a much more modest technique of ‘a one bit field of each header is pre-defined as a “packet error indicator”‘ is described in the patent and claims and is included in the pool. One might characterize as a “damaged in transit” flag — simply notification of “an uncorrectable error occurred”, not error correction.