H261_A

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).

Structure Member Constant

wRestrictedMode

DXVA_RESTRICTED_MODE_H261_A

Restrictions on DXVA_PictureParameters

The following restrictions on the DXVA_PictureParameters structure apply when the bDXVA_Func variable defined by the dwFunction member of DXVA_ConfigPictureDecode is equal to 1.

Structure Member Value

bBPPMinus1

7

bSecondField

Zero

bMacroblockWidthMinus1

15

bMacroblockHeightMinus1

15

bBlockWidthMinus1

7

bBlockHeightMinus1

7

bChromaFormat

1 (4:2:0)

bPicStructure

3 (frame structured)

bMVprecisionAndChromaRelation

2 (H.261 integer-sample motion)

bPicExtrapolation

Zero

bPicDeblocked

Zero

bPic4MVallowed

Zero

bPicOBMC

Zero

bMV_RPS

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

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.

Structure Member Value

MotionType

2 (frame motion) if the MotionForward variable defined in the wMBtype member of these structures equals 1.

MBscanMethod

Zero (zigzag) if the bConfigHostInverseScan member of

DXVA_ConfigPictureDecode equals zero.

FieldResidual

Zero (frame residual)

MotionBackward

Zero (no backward prediction)

Restrictions on Bitstream Buffers

The contents of any bitstream buffer must contain data in the H.261 video format.

This restriction applies when the bDXVA_Func variable defined by the dwFunction member of DXVA_ConfigPictureDecode is equal to 1.

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