D3D12_VIDEO_ENCODER_PICTURE_CONTROL_DESC structure (d3d12video.h)

Describes a video encoder picture control.

Syntax

typedef struct D3D12_VIDEO_ENCODER_PICTURE_CONTROL_DESC {
  UINT                                           IntraRefreshFrameIndex;
  D3D12_VIDEO_ENCODER_PICTURE_CONTROL_FLAGS      Flags;
  D3D12_VIDEO_ENCODER_PICTURE_CONTROL_CODEC_DATA PictureControlCodecData;
  D3D12_VIDEO_ENCODE_REFERENCE_FRAMES            ReferenceFrames;
} D3D12_VIDEO_ENCODER_PICTURE_CONTROL_DESC;

Members

IntraRefreshFrameIndex

When requesting an intra-refresh wave for IntraRefreshFramesDuration frames by specifying the D3D12_VIDEO_ENCODER_SEQUENCE_CONTROL_FLAG_REQUEST_INTRA_REFRESH flag, this value indicates, for the current picture, the index of the frame in the intra-refresh wave. The value range is set by the host between 0 and IntraRefreshFramesDuration to hint the status of the intra-refresh session to the driver.

Flags

A bitwise OR combination of values from the D3D12_VIDEO_ENCODER_PICTURE_CONTROL_FLAGS enumeration specifying the picture control descriptor flags.

PictureControlCodecData

A D3D12_VIDEO_ENCODER_PICTURE_CONTROL_CODEC_DATA structure containing codec-specific picture control data. Depending of the selected rate control mode the QP values are interpreted differently.

ReferenceFrames

A D3D12_VIDEO_ENCODE_REFERENCE_FRAMES structure containing the reconstructed pictures from the past encoding operations outputs.

Remarks

The following remarks provide guidance for frame management.

The host calls EncodeFrame in encode order based in the picture type periodic sequence configured in the codec GOP structure after doing the B-frame reordering by POC if needed. Different codecs will use their own ways of indexing this structure and keeping their state metadata. Refer to the codec picture parameters also passed in the EncodeFrame operation that contain such details.

D3D12_VIDEO_ENCODER_SUPPORT_FLAG_RECONSTRUCTED_FRAMES_REQUIRE_TEXTURE_ARRAYS specifies the requirement of texture arrays for the ppTexture2Ds and pSubresources fields of the D3D12_VIDEO_ENCODE_REFERENCE_FRAMES structure.

The output of the encode operation for a given frame must also return the reconstructed picture if marked as used as reference for future usage in next frames, the client passes the reconstructed pictures in future EncodeFrame commands.

If coding temporal layers, a picture can only use as references pictures on lower TemporalLayerIndex than its own. The temporal layer indices are specified in the picture control structure and in the reference picture descriptors.

The HW limitations for the number of reference pictures are expressed in terms of the maximum number of elements present in L0 (MaxL0ReferencesForP/MaxL0ReferencesForB) and L1 (MaxL1ReferencesForB) lists and limiting by MaxDPBCapacity the maximum number of unique indices in (L0 union L1) that map into the value of pReferenceFramesReconPictureDescriptors provided in D3D12_VIDEO_ENCODER_PICTURE_CONTROL_CODEC_DATA.

There's no limitation to the number of DPB entries being passed in pReferenceFramesReconPictureDescriptors, but instead in the number of entries on that array being references by the L0 and L1 lists. This allows the user to track the state of a DPB in pReferenceFramesReconPictureDescriptors within the restrictions defined by the codec standard limitations and only use a subset restricted by the hardware limitations when calling EncodeFrame. For example, for HEVC encoding, the caller could keep track of the latest 15 encoded pictures in pReferenceFramesReconPictureDescriptors but only use a subset of the pictures that falls within the hardware restrictions, by assigning a limited number of unique indices in the L0 and L1 lists.

Note that a request for an IDR frame will act as a barrier between frame references and the DPB buffer and its state might need to be flushed accordingly by the host.

Requirements

Requirement	Value
Minimum supported client	Windows Build 22000
Minimum supported server	Windows Build 22000
Header	d3d12video.h