C Specification

When calling vkGetPhysicalDeviceVideoCapabilitiesKHR to query the capabilities for an H.264 encode profile, the VkVideoCapabilitiesKHR::pNext chain must include a VkVideoEncodeH264CapabilitiesKHR structure that will be filled with the profile-specific capabilities.

The VkVideoEncodeH264CapabilitiesKHR structure is defined as:

// Provided by VK_KHR_video_encode_h264
typedef struct VkVideoEncodeH264CapabilitiesKHR {
    VkStructureType                        sType;
    void*                                  pNext;
    VkVideoEncodeH264CapabilityFlagsKHR    flags;
    StdVideoH264LevelIdc                   maxLevelIdc;
    uint32_t                               maxSliceCount;
    uint32_t                               maxPPictureL0ReferenceCount;
    uint32_t                               maxBPictureL0ReferenceCount;
    uint32_t                               maxL1ReferenceCount;
    uint32_t                               maxTemporalLayerCount;
    VkBool32                               expectDyadicTemporalLayerPattern;
    int32_t                                minQp;
    int32_t                                maxQp;
    VkBool32                               prefersGopRemainingFrames;
    VkBool32                               requiresGopRemainingFrames;
    VkVideoEncodeH264StdFlagsKHR           stdSyntaxFlags;
} VkVideoEncodeH264CapabilitiesKHR;

Members

  • sType is a VkStructureType value identifying this structure.

  • pNext is NULL or a pointer to a structure extending this structure.

  • flags is a bitmask of VkVideoEncodeH264CapabilityFlagBitsKHR indicating supported H.264 encoding capabilities.

  • maxLevelIdc is a StdVideoH264LevelIdc value indicating the maximum H.264 level supported by the profile, where enum constant STD_VIDEO_H264_LEVEL_IDC_<major>_<minor> identifies H.264 level <major>.<minor> as defined in section A.3 of the ITU-T H.264 Specification.

  • maxSliceCount indicates the maximum number of slices that can be encoded for a single picture. Further restrictions may apply to the number of slices that can be encoded for a single picture depending on other capabilities and codec-specific rules.

  • maxPPictureL0ReferenceCount indicates the maximum number of reference pictures the implementation supports in the reference list L0 for P pictures.

    Note

    As implementations may override the reference lists, maxPPictureL0ReferenceCount does not limit the number of elements that the application can specify in the L0 reference list for P pictures. However, if maxPPictureL0ReferenceCount is zero, then the use of P pictures is not allowed.

  • maxBPictureL0ReferenceCount indicates the maximum number of reference pictures the implementation supports in the reference list L0 for B pictures.

  • maxL1ReferenceCount indicates the maximum number of reference pictures the implementation supports in the reference list L1 if encoding of B pictures is supported.

    Note

    As implementations may override the reference lists, maxBPictureL0ReferenceCount and maxL1ReferenceCount does not limit the number of elements that the application can specify in the L0 and L1 reference lists for B pictures. However, if maxBPictureL0ReferenceCount and maxL1ReferenceCount are both zero, then the use of B pictures is not allowed.

  • maxTemporalLayerCount indicates the maximum number of H.264 temporal layers supported by the implementation.

  • expectDyadicTemporalLayerPattern indicates that the implementation’s rate control algorithms expect the application to use a dyadic temporal layer pattern when encoding multiple temporal layers.

  • minQp indicates the minimum QP value supported.

  • maxQp indicates the maximum QP value supported.

  • prefersGopRemainingFrames indicates that the implementation’s rate control algorithm prefers the application to specify the number of frames of each type remaining in the current group of pictures when beginning a video coding scope.

  • requiresGopRemainingFrames indicates that the implementation’s rate control algorithm requires the application to specify the number of frames of each type remaining in the current group of pictures when beginning a video coding scope.

  • stdSyntaxFlags is a bitmask of VkVideoEncodeH264StdFlagBitsKHR indicating capabilities related to H.264 syntax elements.

Description

Valid Usage (Implicit)

  • VUID-VkVideoEncodeH264CapabilitiesKHR-sType-sType
    sType must be VK_STRUCTURE_TYPE_VIDEO_ENCODE_H264_CAPABILITIES_KHR

See Also

VK_KHR_video_encode_h264, VkBool32, VkStructureType, VkVideoEncodeH264CapabilityFlagsKHR, VkVideoEncodeH264StdFlagsKHR

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 2014-2024 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0