The Vulkan APi calls out to the same hardware. The benefit of using it via Vulkan is that you (in theory) don’t need to have multiple APIs for different GPU vendors.
It's also meant to make it (somewhat) easier to apply various GPGPU filters and scalers before encode or after decode, like HDR tonemapping. The OS usually has some method to do this while keeping the data in the GPU VRAM by passing a handle from one API subsystem to another but if it never leaves Vulkan you don't have to worry about getting that right.
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The Vulkan APi calls out to the same hardware. The benefit of using it via Vulkan is that you (in theory) don’t need to have multiple APIs for different GPU vendors.
It's also meant to make it (somewhat) easier to apply various GPGPU filters and scalers before encode or after decode, like HDR tonemapping. The OS usually has some method to do this while keeping the data in the GPU VRAM by passing a handle from one API subsystem to another but if it never leaves Vulkan you don't have to worry about getting that right.