That's very old news, Since 2013 hardware H265 decoding has been a thing (Samsung Galaxy S4 debuted with it), maybe not in the Pi's price range but it's now four years later and counting. And Hardkernel isn't the only company with a low cost Hardware H265 decoder, Amlogic S805 does it too for about $50AUD, slightly cheaper than the Pi3 here in Australia.
No hardware support on the Pi in the old VC4 for h.265 because it was designed before h.265.
A really good programmer might be able to do h.265 in software on 64bit Aarch64 with NEON help?
I think Pi was done in 40nm and h.265 hardware needs 28nm?
Yes, the Pi3, but this thread is about the Pi4 is it not? If the Pi4 is still on 40nm technology we might as well be saying good bye to the Pi. Everyone is bringing out low cost credit card sized boards these days, the NanoPi's by Friendly Arm are less than the cost of the Pi with almost identical specs except at a much smaller size.
H264 and H265 are actually very similar, so H264 quality can be just as good as H265, but just requires more bits to do it. H265 can do similar quality to H264 but as sometimes lesss than half the bitrate, as you state. Much of the difference is down to allowing arbitrary macroblock sizes.
However, H265 is different enough to require a completely new HD design. And designing an HEVC/H265 codec in HW is not easy, and therefor not cheap. It requires exceptionally fast and clever HW and also RAM, which means better memory controllers etc, especially if you want to encode. Decoding is easier, but still requires the HW change.
This is not available on the VC4. Which is why the Pi doesn't have it. To move to H265 would require a new chip. And new chips are VERY expensive to make.
You can use the ARM cores for H265 decoding - you can I believe get some pretty impressive performance using all four cores and NEON. 720p30 is easily achievable. However,you will likely need a heatsink.
Yes all true, I can't argue with any of what you said. I understand H265 HW support needs some fast and clever HW, the existing Pi3 will never be able to do reliable H265 decoding at 30fps 1080p+ and neither will the design improvements in the future based on the existing architecture. Maybe if H265 have some breakthrough on the decoding side of things that allows decoding with less grunt, but that's wishful thinking at this stage...
I know it's hard from Pi's perspective, so many people wanting the world from a inexpensive SBC. I'm just hoping (key word 'hopeing') things like H265 support won't be overlooked in the Pi4 because it'll be a real deal breaker for me and quite a few people I reckon. Everything else in the Pi3 is spot on, grunt is good, memory is adequate, connectivity is okay (100Mbps Network and USB2 can limit what you do with the Pi though, again wanting the world from a SBC...).
I know the Pi originally set out to be a low cost learning tool but it's being used for so much more. I see things like Pi based PLC's, media centers, weather stations, data loggers, etc and it's fantastic. The absolute best thing about the Pi is the support from the community, everything just works the way it should unlike some of the other players (like Hardkernel) that release things half finished. That's why I want H265 support so badly in the Pi4 because I know it will work, and work well, if Pi decide to implement it that is
I also know we won't get any answers about the next Pi release, I've seen many of these threads and they all end the same...