FFV1 fix

[vadosnaprimer]

Change pixel format from BGRA to BGR0

For this kind of footage carrying alpha information makes no sense, and it additionally complicates things by hugely damaging compatibility of the resulting video. After this change alone the video becomes compatible with VfW/WinAPI and tools that rely on it (avisynth, virtualdub).

Fixes https://bugs.dolphin-emu.org/issues/11141 and https://bugs.dolphin-emu.org/issues/10193

Note that internally pixel format seems to be RGBA or BGR24, but then it's converted to whatever is set for ffmpeg, and I'm only changing the latter.

Decrease gop size (keyint)

This makes seeking a lot smoother (especially at high resolutions), while only adding less than 1% of filesize overhead with this codec.

[stenzek]

Could you please rebase this on the latest master? Looks like our FifoCI buildbots are failing to build because it's missing the ICE fix.

[stenzek]

LGTM. The alpha channel should be set to 1 anyway for all frames, so I can't see this hurting anything.

FifoCI says it's fine (FFV1 is used for frame dumping there IIRC).

[JosJuice]

You'll need to rebase the branch so that there isn't a merge commit in it.

[vadosnaprimer]

@JosJuice will it remain there if the PR is squashed? I don't know what went wrong on my end. Commits got duplicated for whatever reason as well, so I wonder if squashing helps, since the diff is just 2 numbers.

[BhaaLseN]

It will not remain in there if you do it properly. They likely got duplicated because you pulled from your own remote before pushing.

You can try one of the following:

1. Rebase on latest master and assume it will-just-work™ (replace origin with our remote name):

git fetch origin
git rebase origin/master ffv1_fix

2. Reset on latest master and redo your commits (unlikely to leave commits behind you don't want):

git fetch origin
git checkout ffv1_fix
git reset --soft origin/master
git commit (or git gui, or your preferred method of committing)

Once this is done and your history looks ok, you want git push -f (or git push -f yourRemote ffv1_fix)

[vadosnaprimer]

Is it okay now? One of the builds failed, but the reason doesn't seem to be relevant.

[JosJuice]

Yeah, it looks fine. The macOS buildbot is just broken in general right now.

@RisingFog, do you want to take a look at this PR?

[RisingFog]

Looks good to me.