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D3D12_VIDEO_ENCODER_PICTURE_CONTROL_CODEC_DATA_H264_REFERENCE_PICTURE_MARKING_OPERATION structure (d3d12video.h)

  • Article

Describes changes in the reference pictures as memory operations as a tuple of an operation identifier and associated parameters needed for the operation.

Syntax

typedef struct D3D12_VIDEO_ENCODER_PICTURE_CONTROL_CODEC_DATA_H264_REFERENCE_PICTURE_MARKING_OPERATION {
  UCHAR memory_management_control_operation;
  UINT  difference_of_pic_nums_minus1;
  UINT  long_term_pic_num;
  UINT  long_term_frame_idx;
  UINT  max_long_term_frame_idx_plus1;
} D3D12_VIDEO_ENCODER_PICTURE_CONTROL_CODEC_DATA_H264_REFERENCE_PICTURE_MARKING_OPERATION;

Members

memory_management_control_operation

The control operation to be applied to affect the reference picture marking state.

difference_of_pic_nums_minus1

Used with memory_management_control_operation equal to 3 or 1 to assign a long-term frame index to a short-term reference picture or to mark a short-term reference picture as "unused for reference".

long_term_pic_num

Used with memory_management_control_operation equal to 2 to mark a long-term reference picture as "unused for reference".

long_term_frame_idx

Used with memory_management_control_operation equal to 3 or 6 to assign a long-term frame index to a picture.

max_long_term_frame_idx_plus1

The value minus 1 specifies the maximum value of long-term frame index allowed for long-term reference pictures (until receipt of another value of max_long_term_frame_idx_plus1).

Remarks

For more information, refer to H264 specification for more details: section 8.2.5.4 "Adaptive memory control decoded reference picture marking process".

The variable MaxLongTermFrameIdx is derived as follows:

– If max_long_term_frame_idx_plus1 is equal to 0, MaxLongTermFrameIdx is set equal to "no long-term frame indices". – Otherwise (max_long_term_frame_idx_plus1 is greater than 0), MaxLongTermFrameIdx is set equal to max_long_term_frame_idx_plus1 − 1.

The operation of marking the current frame as a short-term reference is given by a flag present in the D3D12_VIDEO_ENCODER_PICTURE_CONTROL_CODEC_DATA_H264_FLAGS structure with its corresponding PictureOrderCountNumber and FrameDecodingOrderNumber values indicated in the associated picture control structure.

The variable max_num_ref_frames is indicated in this API by the maximum DPB capacity reported.

Note that for marking an IDR frame as long-term reference, the proposed explicit mechanism is to mark it as short term reference first, by setting D3D12_VIDEO_ENCODER_PICTURE_CONTROL_FLAG_USED_AS_REFERENCE_PICTURE when calling EncodeFrame for the IDR frame, and later promoting it to be a long-term reference frame using memory management operation '3' to mark a short-term reference picture as "used for long-term reference" and assign a long-term frame index to it.

Alternatively, if encoding an IDR frame and setting adaptive_ref_pic_marking_mode_flag = 1, the driver will assume that the client is attempting to set the H264 slice header long_term_reference_flag and will do so in the output bitstream for the EncodeFrame call.

Requirements

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