MPEG-4 was based heavily on H.263 for progressive-scan coding, and on MPEG-2 for support of interlace and color sampling formats other than 4:2:0. The features that support H.263 and MPEG-2 can be used to support MPEG-4.
MPEG-4 can support a sample accuracy of more than 8 bits. DirectX VA includes a mechanism to support more than 8 bits per pixel using the bBPPminus1 member of the DXVA_PictureParameters structure.
Note The features most unique to MPEG-4, such as shape coding, object orientation, face modeling, mesh objects, and sprites, are not supported in DirectX VA.