VkVideoEncodeRgbRangeCompressionFlagBitsVALVE(3)

C Specification

The video encode R′G′B′ range compression to be applied to color component values of the encode input picture before video coding is defined by the rgbRange member of the VkVideoEncodeSessionRgbConversionCreateInfoVALVE structure.

The VkVideoEncodeRgbRangeCompressionFlagBitsVALVE enum describes whether color components are encoded using the full range of numerical values or whether values are reserved for headroom and foot room:

// Provided by VK_VALVE_video_encode_rgb_conversion
typedef enum VkVideoEncodeRgbRangeCompressionFlagBitsVALVE {
    VK_VIDEO_ENCODE_RGB_RANGE_COMPRESSION_FULL_RANGE_BIT_VALVE = 0x00000001,
    VK_VIDEO_ENCODE_RGB_RANGE_COMPRESSION_NARROW_RANGE_BIT_VALVE = 0x00000002,
} VkVideoEncodeRgbRangeCompressionFlagBitsVALVE;

Description

VK_VIDEO_ENCODE_RGB_RANGE_COMPRESSION_FULL_RANGE_BIT_VALVE specifies the following transformations are applied:

Y^{'} C_{B} C_{R} = C_{r g ba}^{'} [G] = C_{r g ba}^{'} [B] - \frac{2 ^{(n - 1)}}{( 2 ^{n} ) - 1} = C_{r g ba}^{'} [R] - \frac{2 ^{(n - 1)}}{( 2 ^{n} ) - 1}

Note

These formulae correspond to the “full range” encoding in the “Quantization schemes” chapter of the Khronos Data Format Specification.

Should any future amendments be made to the ITU specifications from which these equations are derived, the formulae used by Vulkan may also be updated to maintain parity.

VK_VIDEO_ENCODE_RGB_RANGE_COMPRESSION_NARROW_RANGE_BIT_VALVE specifies the following transformations are applied:

Y^{'} C_{B} C_{R} = \frac{C _{r g ba}^{'} [ G ] \times ( 2 ^{n} - 1 ) - 16 \times 2 ^{n - 8}}{219 \times 2 ^{n - 8}} = \frac{C _{r g ba}^{'} [ B ] \times ( 2 ^{n} - 1 ) - 128 \times 2 ^{n - 8}}{224 \times 2 ^{n - 8}} = \frac{C _{r g ba}^{'} [ R ] \times ( 2 ^{n} - 1 ) - 128 \times 2 ^{n - 8}}{224 \times 2 ^{n - 8}}

Note	These formulae correspond to the “narrow range” encoding in the “Quantization schemes” chapter of the Khronos Data Format Specification. Unlike sampler Y′C_BC_R range expansion, no precision guarantees are made for video encode R′G′B′ range compression.

n is the bit-depth of the components in the bound video session’s pictureFormat.

Note	Video encode R′G′B′ range compression transformations have the inverse definition of the sampler Y′C_BC_R range expansion transformations.

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

SPDX-License-Identifier: CC-BY-4.0

VkVideoEncodeRgbRangeCompressionFlagBitsVALVE(3) Manual Page

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