Good to know. Didn't know H.261 had it. I know MPEG4 (H.264) has it. MPEG4 was like coming out in 1990s/2000s? It's pretty old. But the idea is the same for all newer codecs. They just have different ways to chop up a frame into blocks and do shifting at the block level.

its been there since VCD (MPEG), DVD (MPEG2) & HDDVD/BR MPEG4-10 or H.264. its a very old idea. In fact it has been used in implementing a temporal filter to create a cleaner content for a bit too. I know because I worked on it all.

Good know. Very interesting.

Modern codecs not only chop the frame into variable size blocks, they also do fractional shifts, in many directions, and predict the shift from past and future and parts of current frame.

I've heard some research into using triangle as macroblock for future codecs. That would really change things up.

Triangle partition mode was in VVC VTM 6, cant remember if it made it into the final spec due to complexity increase.