C Specification

The VkVideoEncodeH265RateControlInfoKHR structure is defined as:

// Provided by VK_KHR_video_encode_h265
typedef struct VkVideoEncodeH265RateControlInfoKHR {
    VkStructureType                         sType;
    const void*                             pNext;
    VkVideoEncodeH265RateControlFlagsKHR    flags;
    uint32_t                                gopFrameCount;
    uint32_t                                idrPeriod;
    uint32_t                                consecutiveBFrameCount;
    uint32_t                                subLayerCount;
} VkVideoEncodeH265RateControlInfoKHR;

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 VkVideoEncodeH265RateControlFlagBitsKHR specifying H.265 rate control flags.

  • gopFrameCount is the number of frames within a group of pictures (GOP) intended to be used by the application. If it is set to 0, the rate control algorithm may assume an implementation-dependent GOP length. If it is set to UINT32_MAX, the GOP length is treated as infinite.

  • idrPeriod is the interval, in terms of number of frames, between two IDR frames (see IDR period). If it is set to 0, the rate control algorithm may assume an implementation-dependent IDR period. If it is set to UINT32_MAX, the IDR period is treated as infinite.

  • consecutiveBFrameCount is the number of consecutive B frames between I and/or P frames within the GOP.

  • temporalLayerCount specifies the number of H.265 sub-layers that the application intends to use.

Description

When an instance of this structure is included in the pNext chain of the VkVideoCodingControlInfoKHR structure passed to the vkCmdControlVideoCodingKHR command, and VkVideoCodingControlInfoKHR::flags includes VK_VIDEO_CODING_CONTROL_ENCODE_RATE_CONTROL_BIT_KHR, the parameters in this structure are used as guidance for the implementation’s rate control algorithm (see Video Coding Control).

If flags includes VK_VIDEO_ENCODE_H265_RATE_CONTROL_ATTEMPT_HRD_COMPLIANCE_BIT_KHR, then the rate control state is reset to an initial state to meet HRD compliance requirements. Otherwise the new rate control state may be applied without a reset depending on the implementation and the specified rate control parameters.

Note

It would be possible to infer the picture type to be used when encoding a frame, on the basis of the values provided for consecutiveBFrameCount, idrPeriod, and gopFrameCount, but this inferred picture type will not be used by implementations to override the picture type provided to the video encode operation.
Valid Usage

  • VUID-VkVideoEncodeH265RateControlInfoKHR-flags-08291
    If VkVideoEncodeH265CapabilitiesKHR::flags, as returned by vkGetPhysicalDeviceVideoCapabilitiesKHR for the used video profile, does not include VK_VIDEO_ENCODE_H265_CAPABILITY_HRD_COMPLIANCE_BIT_KHR, then flags must not contain VK_VIDEO_ENCODE_H265_RATE_CONTROL_ATTEMPT_HRD_COMPLIANCE_BIT_KHR

  • VUID-VkVideoEncodeH265RateControlInfoKHR-flags-08292
    If flags contains VK_VIDEO_ENCODE_H265_RATE_CONTROL_REFERENCE_PATTERN_FLAT_BIT_KHR or VK_VIDEO_ENCODE_H265_RATE_CONTROL_REFERENCE_PATTERN_DYADIC_BIT_KHR, then it must also contain VK_VIDEO_ENCODE_H265_RATE_CONTROL_REGULAR_GOP_BIT_KHR

  • VUID-VkVideoEncodeH265RateControlInfoKHR-flags-08293
    If flags contains VK_VIDEO_ENCODE_H265_RATE_CONTROL_REFERENCE_PATTERN_FLAT_BIT_KHR, then it must not also contain VK_VIDEO_ENCODE_H265_RATE_CONTROL_REFERENCE_PATTERN_DYADIC_BIT_KHR

  • VUID-VkVideoEncodeH265RateControlInfoKHR-flags-08294
    If flags contains VK_VIDEO_ENCODE_H265_RATE_CONTROL_REGULAR_GOP_BIT_KHR, then gopFrameCount must be greater than 0

  • VUID-VkVideoEncodeH265RateControlInfoKHR-idrPeriod-08295
    If idrPeriod is not 0, then it must be greater than or equal to gopFrameCount

  • VUID-VkVideoEncodeH265RateControlInfoKHR-consecutiveBFrameCount-08296
    If consecutiveBFrameCount is not 0, then it must be less than gopFrameCount

Valid Usage (Implicit)

  • VUID-VkVideoEncodeH265RateControlInfoKHR-sType-sType
    sType must be VK_STRUCTURE_TYPE_VIDEO_ENCODE_H265_RATE_CONTROL_INFO_KHR

  • VUID-VkVideoEncodeH265RateControlInfoKHR-flags-parameter
    flags must be a valid combination of VkVideoEncodeH265RateControlFlagBitsKHR values

See Also

VK_KHR_video_encode_h265, VkStructureType, VkVideoEncodeH265RateControlFlagsKHR

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