VkVideoEncodeH264RateControlInfoKHR

The VkVideoEncodeH264RateControlInfoKHR structure is defined as:

typedef struct VkVideoEncodeH264RateControlInfoKHR {
    VkStructureType sType;
    const void* pNext;
    VkVideoEncodeH264RateControlFlagsKHR flags;
    uint32_t gopFrameCount;
    uint32_t idrPeriod;
    uint32_t consecutiveBFrameCount;
    uint32_t temporalLayerCount;
} VkVideoEncodeH264RateControlInfoKHR;

• 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 VkVideoEncodeH264RateControlFlagBitsKHR specifying H.264 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 0, the rate control algorithm may assume an implementation-dependent GOP length. If it is 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 0, the rate control algorithm may assume an implementation-dependent IDR period. If it is 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.264 temporal layers that the application intends to use.

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_H264_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.