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MPEG1_A

The MPEG1_A restricted profile contains a set of features required for support of MPEG-1 video. Support of this profile is required for video accelerator drivers that provide hardware video acceleration capabilities. This set of features is defined by the following set 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_MPEG1_A

Restrictions on DXVA_PictureParameters

Structure Member Value

BPP variable (defined by adding 1 to bBPPminus1)

Equals 8

bSecondField

Equals zero

MacroblockWidthMinus1

15

MacroblockHeightMinus1

15

bBlockWidthMinus1

7

bBlockHeightMinus1

7

bChromaFormat (4:2:0)

1

bPicStructure

3 (frame structured)

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

Zero

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

MotionType

2 (frame motion)

MBscanMethod

Zero (zigzag) if bConfigHostInverseScan equals zero

FieldResidual

Zero (frame residual)

H261LoopFilter

Zero (no H.261 loop filter)

Restrictions on Bitstream Buffers

The contents of any bitstream buffer must contain data in the MPEG-1 main profile video format.