[UNTESTED] Highly experimental H264 support for G45/CTG

[irql-notlessorequal]

I'm leaving this out for several releases since this is a mess.

My gripes with it is that:

1. This isn't real hardware acceleration, I mean sure, it runs on the GPU alright but this is just doing the number crunching on it, no actual dedicated silicon.
2. It's very bug prone and likely to just hang your GPU.
3. GPU configurations vary the maximum resolution, meaning that the luckiest users will be able to handle 1080p30/720p60.
4. No VPP support, meaning that Chromium WILL NOT work with this generation of hardware.

I'm leaving this PR here for the poor souls that want to test this.

As of writing, this is using the unmodified shaders for CTG, they might work or they might not.

Please leave feedback here, or yell at me to make a dedicated issue tracker for this specific issue.

Compiling this requires setting -Denable_h264_ctg=true in Meson or --enable-h264-ctg in Make.

[w8jcik]

Could you suggest which software might make use of this acceleration? Is it VLC, MPlayer, ffmpeg?

I can see pretty clear in the README.md that this solution offers Functioning Chromium support (except for G45 of course). Is Firefox more problematic or less problematic, or simply different? Does it have a chance to work?

[irql-notlessorequal]

Could you suggest which software might make use of this acceleration? Is it VLC, MPlayer, ffmpeg?

I can see pretty clear in the README.md that this solution offers Functioning Chromium support (except for G45 of course). Is Firefox more problematic or less problematic, or simply different? Does it have a chance to work?

Assuming it works (probably need to rebase the changes and add some missing patches), most software should be able to take advantage of it, Chromium is the odd one out because it is using VPP [1] (post-processing using GPU shaders) to convert the raw NV12 image you get from decoding into BGRA unlike everyone else.

[1] This isn't supported on G45 because the GPU is way more limited in capabilities (to be fair it is a very old integrated graphics solution) and Intel didn't provide any shaders to do conversion with.