So when you decode using hardware acceleration the library you're using usually handles writing the output to the backing store which lets you get performant ha

So when you decode using hardware acceleration the library you're using usually handles writing the output to the backing store which lets you get performant hardware accelerate video inside a compositor. The problem when you're trying to use it as a texture inside Vulkan is that, best case scenario, the library then has to copy the data out to system memory, then provides a pointer to that buffer to your Vk app, then you have to copy it back into texture memory. Worst case scenario the library falls back to CPU decoding because of the final destination of the frame being system memory. Vulkan video is going to allow that video decoding to render straight to a Vulkan texture in texture memory bypassing the copy out and copy back in. It'll be far more performant than having to copy it twice across the PCIe bus taking up valuable system memory bandwidth to the CPU doing literally nothing.