[niftich]

~1993 is around when CompuServe and Unisys began negotiating about the implications of patented LZW in GIF files, but the issue didn't become public until 1994, but the community rebounded spectacularly by developing PNG in 1995.

So perhaps the cutoff year of 1993 is right before the threat of non-pooled patents was well-publicized.

There was a lot of video codec innovation back then too, but everything aside from the MPEG or ITU-T codecs was proprietary, and everyone took out patents. To Monty's point, the sheer number of endpoints capable of consuming digital video whose consumption somehow results in income for the publishers was just not quite there, making an alternate push for deriving revenue from DSP IP than patent licensing fees much less likely.