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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.