DirectX11 should not be made the default

[softworkz]

No doubt, using DX11 offers a number of important advantages:

• It doesn't require a monitor to be connected => Headless operation
• It doesn't require a Windows User Session => Can be used from a Windows Service

But that doesn't mean that DX11 is always the better choice:

• Some Windows versions do not support DX11
• Certain MSDK versions advertise DX11 support, but don't implement it properly (= fails)
• Specifically with your implementation: Only the latest MSDK versions support DX11 array textures. Earlier versions don't support that and when you choose DX11 by default, it will always fail in those cases

Most Importantly:

• ffmpeg should not introduce a fundamental change like this all of a sudden and without any hard technical requirement

IMO, the default behavior should remain unchanged

[softworkz]

For all 4th and 5th Gen CPUs, the SDK version (when using the latest driver) is 1.20

SDK 1.20 supports DX11 - but just somewhat. So when you would make DX11 the default in ffmpeg, ffmpeg would fail for all those CPUs (at least when it comes to use filtering).

The same is true for all Gen 3 CPUs (see #1)

=> When ffmpeg would change the default to DX11, it would fail (by default) for all users having Gen 3, Gen 4 and Gen 5 CPUs.