Buffer Description List
DirectX VA operates primarily by passing buffers of data from the host decoder to the hardware accelerator. When a set of buffers is passed from the host to the accelerator, a buffer description list is sent to describe the buffers. A buffer description list is an array of DXVA_BufferDescription structures. The buffer description list contains one DXVA_BufferDescription structure for each buffer in the set of buffers being sent. The buffer description list starts with one or more DXVA_BufferDescription structures for the first type of buffer being sent. This is followed by one or more DXVA_BufferDescription structures for the next type of buffer being sent, and so on.
The value of the dwTypeIndex member of the DXVA_BufferDescription structure specifies what type of buffer is passed from the host to the accelerator.