MPEG2_A

The MPEG2_A restricted profile contains a set of features required for support of MPEG-2 video Main Profile. Support of this profile is required for video accelerator drivers that provide hardware video acceleration capabilities.

The MPEG2_A profile is defined by the following sets of restrictions:

Restrictions on DXVA_ConnectMode

The following restriction on the DXVA_ConnectMode structure applies when the bDXVA_Func variable defined in the dwFunction member of the DXVA_ConfigPictureDecode structure is equal to 1.

Structure Member	Value
wRestrictedMode	DXVA_RESTRICTED_MODE_MPEG2_A

Restrictions on DXVA_PictureParameters

Structure Member	Value
wRestrictedMode	0x0A
BPP variable (defined by adding 1 to bBPPminus1)	8
MacroblockWidthMinus1	15
MacroblockHeightMinus1	15
bBlockWidthMinus1	7
bBlockHeightMinus1	7
bChromaFormat (4:2:0)	1
bRcontrol	Zero
bBidirectionalAveragingMode	Zero (MPEG-2 bidirectional averaging)
bMVprecisionAndChromaRelation	Zero (MPEG-2 half-sample motion)
bPicExtrapolation	Zero
bPicDeblocked	Zero
bPic4MVallowed	Zero
bPicOBMC	Zero
bMV_RPS	Zero
SpecificIDCT	Zero
bPicScanFixed	1

Restrictions on DXVA_MBctrl_I_HostResidDiff_1, DXVA_MBctrl_I_OffHostIDCT_1, DXVA_MBctrl_P_HostResidDiff_1, and DXVA_MBctrl_P_OffHostIDCT_1

wMBtype Bits	Value
MBscanMethod	May be a value of zero (zigzag) or a value of 1 (alternate vertical) if the ConfigHostInverseScan member of DXVA_ConfigPictureDecode is equal to zero.
H261LoopFilter	Zero

Restrictions on Bitstream Buffers

The contents of any bitstream buffer must contain data in the MPEG-2 main profile video format.

The bNewQmatrix member of DXVA_QmatrixData equals zero, for i = 2 and 3 when inverse-quantization matrices are used.