The H261_A restricted profile contains the set of features required for minimal support of ITU-T Rec. H.261 without acceleration support for H.261 Annex D graphics. Support of this profile is currently encouraged, but not required. This set of features is defined by the following restrictions.
Restrictions on DXVA_ConnectMode
The following restriction on the DXVA_ConnectMode structure applies when the bDXVA_Func variable defined by the dwFunction member of the DXVA_ConfigPictureDecode structure is equal to 1 (picture decoding).
Restrictions on DXVA_PictureParameters
3 (frame structured)
2 (H.261 integer-sample motion)
Restrictions on DXVA_MBctrl_I_HostResidDiff_1, DXVA_MBctrl_I_OffHostIDCT_1, DXVA_MBctrl_P_HostResidDiff_1, and DXVA_MBctrl_P_OffHostIDCT_1
The following restrictions on the DXVA_MBctrl_I_HostResidDiff_1, DXVA_MBctrl_I_OffHostIDCT_1, DXVA_MBctrl_P_HostResidDiff_1, and DXVA_MBctrl_P_OffHostIDCT_1 structures apply when the bDXVA_Func variable defined by the dwFunction member of DXVA_ConfigPictureDecode is equal to 1.
2 (frame motion) if the MotionForward variable defined in the wMBtype member of these structures equals 1.
Zero (zigzag) if the bConfigHostInverseScan member of
DXVA_ConfigPictureDecode equals zero.
Zero (frame residual)
Zero (no backward prediction)
Restrictions on Bitstream Buffers
The contents of any bitstream buffer must contain data in the H.261 video format.