Example/demo of VK_KHR_sampler_ycbcr_conversion

I’m trying to use the VK_KHR_sampler_ycbcr_conversion extension (a Vulkan 1.1 feature) to convert Ycbcr video to RGB. The extension specification is a bit light on details. Does NVIDIA or anyone else have an example of using this feature?

I’m presently using VK_FORMAT_G8_B8R8_2PLANE_420_UNORM and have created the (immutable) ycbcr->rgb conversion sampler and image view but instead of seeing a full color image, I see a “green scale” image (presumably the luminance channel).