So how does this work out fee/patentwise in the OSS world? I know ffmpeg/libav can play HEVC/x265 streams (or at least mpv can). Can it not encode to HEVC? Or do the fees start to apply when you start distributing content? Or is it like mp3 where fees are only attached to hardware encoders/decoders (which gets all iffy because where do you draw the line between hardware sold for encoding/decoding that has software codecs on it vs general purpose OSes with the same codecs?)
And doesn't Firefox have some special deal with Cisco to use their x264 decoder on the web?
ffmpeg just ignores patent licensing - you're responsible for paying the appropriate licensing fees if you use it. The same applies to x264 and x265. Generally the pools won't go after ffmpeg itself but rather companies shipping it once they get big enough / have money. For example: https://github.com/mbebenita/Broadway/issues/124
HEVC is currently literally impossible to license. One of the pools hasn't decided on pricing yet. You basically have to set aside some cash and hope it's enough to back-pay once they announce the pricing. But even with the existing ones, you have to pay for encoders, decoders, and videos encoded in it. https://en.wikipedia.org/wiki/High_Efficiency_Video_Coding#P...
There's no special deal per se, Cisco released OpenH264 for everyone, and it can be used royalty-free as long as you only use the binaries (instead of the source): https://en.wikipedia.org/wiki/OpenH264
And doesn't Firefox have some special deal with Cisco to use their x264 decoder on the web?