h264 is the most available but probably not the most used. Every streaming service today either seeds AV1, VP9, or HEVC content first since it saves bandwidth[0] and every client from the past 5 years supports one of these newer formats (phones, GPUs, smart TVs, streaming boxes, etc).
H.264 is effectively the MP3 of video today: It provides neither the best quality, nor is it patent free (yet), but if an SoC supports any hardware accleration at all, H.264 is usually on the list.
Applications/services that can afford the overhead of multiple format encoding will do so, but it's not always an option.
Most devices can indeed most likely handle software decode of more common resolutions, codecs and bitrates. But I'd really hope they'd pick the one that won't suck up all the battery, so H264. This line of thought is supported by the fact that YouTube still provides an H264 option with most if not all videos.
With higher bitrate things, HEVC seems to grow in popularity but even software decode support is not everywhere. Netflix for example requires the installation of HEVC support on Windows to play 4K content.
Actually hardware-accelerated video decode is even spottier and more unreliable across most platforms. The JS API for codec support (canPlayType) literally returns "maybe" and "probably". It's quite bad.
So far the best compatibility I've seen has been Edge with flags on Windows (MPEG-2, H264, HEVC, AV1, VP8, VP9 with most also supporting accelerated encode). It still fails with some content (Dolby Vision P5 colors are incorrect, HEVC Rext doesn't play - more info about HEVC is available here https://github.com/StaZhu/enable-chromium-hevc-hardware-deco...). Chrome on macOS is a close second in terms of codec support.
The worst in terms of HW acceleration being all the browsers on desktop Linux-s, few and fragile combinations that offer limited and janky support. But it's slowly improving. This combined with the not-the-latest hardware many use, means things like VP9 or AV1 tend to stutter.
I'd love to see some more generic stats, but considering the APIs aren't sufficient to determine actual support, these might be difficult to gather.
But all things considered, I heavily doubt dropping H264 HW decode support was a good idea considering how often its still used.
The largest VOD services stopped using H.264 in any meaningful way or only as a last resort, bandwidth is just too expensive to justify using it. Even phones in third world countries include VP9 and HEVC hw decode, it's rare to run into someone who can only play H.264 unless you are walking in sub-Saharan Africa.
If you look at the scene (aka piracy) every rip from every service is in AVC for FHD or HEVC for UHD. I know you mentioned last resort but the only legit streaming service I have at the moment is Apple TV+ and on fire tv’s at least they are sending h264
I’m also in iptvland and every rip from every live service is in h264 as well, with rare UHD feeds using h265 with HLG for HDR
(For clarification, rip means the exact bits sent from the service with no reencoding, just stripping drm)
True, but hardware support does wonders for power consumption. I'm blown away that I can watch 3 hours of h264 content on my flights and only 5% of my iPad battery is used. i.e. more factors to consider than simply whether it can/can't with brute force.
No lyin'. I have an iPad Pro 12.9", 5th generation. I download content on Netflix, Prime, and to VLC prior to flights. During flights I have the iPad in airplane mode and use my AirPod Pros for audio. On my flights from California to Texas, ~3 hrs, I use somewhere between 5-8% battery life. Brightness is probably on the low side because the cabin is dim.
Airplane mode (turning off most of the wireless) seems to be a big factor as well.
