# VkVideoEncodeRateControlModeFlagBitsKHR(3) Manual Page

## Name

VkVideoEncodeRateControlModeFlagBitsKHR - Video encode rate control modes

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## C Specification

The rate control modes are defined with the following enums:

    // Provided by VK_KHR_video_encode_queue
    typedef enum VkVideoEncodeRateControlModeFlagBitsKHR {
        VK_VIDEO_ENCODE_RATE_CONTROL_MODE_DEFAULT_KHR = 0,
        VK_VIDEO_ENCODE_RATE_CONTROL_MODE_DISABLED_BIT_KHR = 0x00000001,
        VK_VIDEO_ENCODE_RATE_CONTROL_MODE_CBR_BIT_KHR = 0x00000002,
        VK_VIDEO_ENCODE_RATE_CONTROL_MODE_VBR_BIT_KHR = 0x00000004,
    } VkVideoEncodeRateControlModeFlagBitsKHR;

## Description

- `VK_VIDEO_ENCODE_RATE_CONTROL_MODE_DEFAULT_KHR` specifies the use of implementation-specific rate control.

- `VK_VIDEO_ENCODE_RATE_CONTROL_MODE_DISABLED_BIT_KHR` specifies that rate control is disabled and the application will specify per-operation rate control parameters controlling the encoding quality. In this mode implementations will encode pictures independently of the output bitrate of prior video encode operations.

  - When using an H.264 encode profile, implementations will use the QP value specified in VkVideoEncodeH264NaluSliceInfoKHR::`constantQp` to control the quality of the encoded picture.

  - When using an H.265 encode profile, implementations will use the QP value specified in VkVideoEncodeH265NaluSliceSegmentInfoKHR::`constantQp` to control the quality of the encoded picture.

  - When using an AV1 encode profile, implementations will use the quantizer index value specified in VkVideoEncodeAV1PictureInfoKHR::`constantQIndex` to control the quality of the encoded picture.

- `VK_VIDEO_ENCODE_RATE_CONTROL_MODE_CBR_BIT_KHR` specifies the use of constant bitrate (CBR) rate control mode. In this mode the implementation will attempt to produce the encoded bitstream at a constant bitrate while conforming to the constraints of other rate control parameters.

- `VK_VIDEO_ENCODE_RATE_CONTROL_MODE_VBR_BIT_KHR` specifies the use of variable bitrate (VBR) rate control mode. In this mode the implementation will produce the encoded bitstream at a variable bitrate according to the constraints of other rate control parameters.

## See Also

VK_KHR_video_encode_queue, VkVideoEncodeQualityLevelPropertiesKHR, VkVideoEncodeRateControlInfoKHR, VkVideoEncodeRateControlModeFlagsKHR

## 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