VkVideoDecodeH264PictureInfoKHR(3)

# VkVideoDecodeH264PictureInfoKHR(3) Manual Page

## Name

VkVideoDecodeH264PictureInfoKHR - Structure specifies H.264 decode picture parameters when decoding a picture

## C Specification

The `VkVideoDecodeH264PictureInfoKHR` structure is defined as:

    // Provided by VK_KHR_video_decode_h264
    typedef struct VkVideoDecodeH264PictureInfoKHR {
        VkStructureType                         sType;
        const void*                             pNext;
        const StdVideoDecodeH264PictureInfo*    pStdPictureInfo;
        uint32_t                                sliceCount;
        const uint32_t*                         pSliceOffsets;
    } VkVideoDecodeH264PictureInfoKHR;

## Members

- `sType` is a VkStructureType value identifying this structure.

- `pNext` is `NULL` or a pointer to a structure extending this structure.

- `pStdPictureInfo` is a pointer to a `StdVideoDecodeH264PictureInfo` structure specifying H.264 picture information.

- `sliceCount` is the number of elements in `pSliceOffsets`.

- `pSliceOffsets` is a pointer to an array of `sliceCount` offsets specifying the start offset of the slices of the picture within the video bitstream buffer range specified in VkVideoDecodeInfoKHR.

## Description

This structure is specified in the `pNext` chain of the VkVideoDecodeInfoKHR structure passed to vkCmdDecodeVideoKHR to specify the codec-specific picture information for an H.264 decode operation.

Decode Output Picture Information

  When this structure is specified in the `pNext` chain of the VkVideoDecodeInfoKHR structure passed to vkCmdDecodeVideoKHR, the information related to the decode output picture is defined as follows:

  - If `pStdPictureInfo->flags.field_pic_flag` is not set, then the picture represents a frame.

  - If `pStdPictureInfo->flags.field_pic_flag` is set, then the picture represents a field. Specifically:

    - If `pStdPictureInfo->flags.bottom_field_flag` is not set, then the picture represents the top field of the frame.

    - If `pStdPictureInfo->flags.bottom_field_flag` is set, then the picture represents the bottom field of the frame.

  - The image subregion used is determined according to the H.264 Decode Picture Data Access section.

  - The decode output picture is associated with the H.264 picture information provided in `pStdPictureInfo`.

Std Picture Information

  The members of the `StdVideoDecodeH264PictureInfo` structure pointed to by `pStdPictureInfo` are interpreted as follows:

  - `reserved1` and `reserved2` are used only for padding purposes and are otherwise ignored;

  - `flags.is_intra` as defined in section 3.73 of the ITU-T H.264 Specification;

  - `flags.is_reference` as defined in section 3.136 of the ITU-T H.264 Specification;

  - `flags.complementary_field_pair` as defined in section 3.35 of the ITU-T H.264 Specification;

  - `seq_parameter_set_id` and `pic_parameter_set_id` are used to identify the active parameter sets, as described below;

  - all other members are interpreted as defined in section 7.4.3 of the ITU-T H.264 Specification.

Reference picture setup is controlled by the value of `StdVideoDecodeH264PictureInfo`::`flags.is_reference`. If it is set and a reconstructed picture is specified, then the latter is used as the target of picture reconstruction to activate the DPB slot specified in `pDecodeInfo->pSetupReferenceSlot->slotIndex`. If `StdVideoDecodeH264PictureInfo`::`flags.is_reference` is not set, but a reconstructed picture is specified, then the corresponding picture reference associated with the DPB slot is invalidated, as described in the DPB Slot States section.

Active Parameter Sets

  The members of the `StdVideoDecodeH264PictureInfo` structure pointed to by `pStdPictureInfo` are used to select the active parameter sets to use from the specified inline parameter sets or from the bound video session parameters object, as follows:

  - The active SPS is the SPS identified by the key specified in `StdVideoDecodeH264PictureInfo`::`seq_parameter_set_id`.

  - The active PPS is the PPS identified by the key specified by the pair constructed from `StdVideoDecodeH264PictureInfo`::`seq_parameter_set_id` and `StdVideoDecodeH264PictureInfo`::`pic_parameter_set_id`.

If the bound video session was created with VK_VIDEO_SESSION_CREATE_INLINE_SESSION_PARAMETERS_BIT_KHR and any of the active parameter sets are specified inline, then the corresponding inline parameter set is used. Otherwise, the parameter set in question is sourced from the bound video session parameters object.

Valid Usage (Implicit)

- VUID-VkVideoDecodeH264PictureInfoKHR-sType-sType
  `sType` must be VK_STRUCTURE_TYPE_VIDEO_DECODE_H264_PICTURE_INFO_KHR

- VUID-VkVideoDecodeH264PictureInfoKHR-pStdPictureInfo-parameter
  `pStdPictureInfo` must be a valid pointer to a valid `StdVideoDecodeH264PictureInfo` value

- VUID-VkVideoDecodeH264PictureInfoKHR-pSliceOffsets-parameter
  `pSliceOffsets` must be a valid pointer to an array of `sliceCount` `uint32_t` values

- VUID-VkVideoDecodeH264PictureInfoKHR-sliceCount-arraylength
  `sliceCount` must be greater than `0`

Structure Chaining

Extends the structure

  - VkVideoDecodeInfoKHR

## See Also

VK_KHR_video_decode_h264, VkStructureType

## Document Notes

For more information, see the Vulkan Specification.

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

## Copyright

Copyright 2014-2026 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0