you can use DirectGMA to transfer the data from you input/grabber card directly to the GPU memory without the need to copy it to system memory first. To take advantage of this peer to peer copy the grabber card needs to support DirectGMA as well. We worked with a couple of SDI vendors to implement DirectGMA support. You will need to check with them to find out which board fits your needs. You can get some more information on the SDI vendors that we support on: http://fireprographics.com/resources/55185A_DirectGMA_FirePro__A4_FNL.pdf
To make use of DirectGMA you do not need a NDA. You will find some information on the API and sample code on: http://developer.amd.com/tools-and-sdks/graphics-development/firepro-sdk/firepro-directgma-sdk/
The basic idea of DirectGMA is that we expose a portion of the GPU memory and make it accessible to other devices on the bus. In order to write into GPU memory those devices will need to get the address of a GPU memory buffer. The APIs that we provide will mainly be used to query those addresses and pass it to the device as well as some additional synchronization functionality.