Name EXT_surface_CTA861_3_metadata Name Strings EGL_EXT_surface_CTA861_3_metadata Contact Courtney Goeltzenleuchter (courtneygo 'at' google.com) Contributors James Jones Weiwan Liu IP Status No known IP claims. Status Complete Version Version 5 - Nov 29, 2016 Number EGL Extension #117 Dependencies This extension requires EGL 1.5 and EGL_EXT_surface_SMPTE2086_metadata. This extension is written against the wording of the EGL 1.5 specification (August 27, 2014). Overview This extension adds additional EGL surface attributes for the metadata defined by the CTA (Consumer Technology Association) 861.3 standard. This metadata, in addition to the SMPTE 2086 metadata, is used to define the color volume of the mastering display as well as the content (CTA-861.3), The mastering display is the display where creative work is done and creative intent is established. To preserve such creative intent as much as possible and achieve consistent color reproduction on different viewing displays, it is useful for the display pipeline to know the color volume of the original mastering display where content is created or tuned. This avoids performing unnecessary mapping of colors that are not displayable on the original mastering display. This extension adds the ability to pass the CTA-861.3 metadata via EGL, from which the color volume can be derived. While the general purpose of the metadata is to assist in the transformation between different color volumes of different displays and help achieve better color reproduction, it is not in the scope of this extension to define how exactly the metadata should be used in such a process. It is up to the implementation to determine how to make use of the metadata. New Procedures and Functions None. New Tokens Accepted as attribute by eglSurfaceAttrib and eglQuerySurface: EGL_CTA861_3_MAX_CONTENT_LIGHT_LEVEL_EXT 0x3360 EGL_CTA861_3_MAX_FRAME_AVERAGE_LEVEL_EXT 0x3361 Additions to Chapter "3.5.6 Surface Attributes" of the EGL 1.5 Specification Add the following paragraph before the "Errors" section on page 43, If attribute is EGL_CTA861_3_MAX_CONTENT_LIGHT_LEVEL_EXT or EGL_CTA861_3_- MAX_FRAME_AVERAGE_LEVEL_EXT, then value indicates the corresponding maximum content light level and maximum frame average level. The unit of value is 1 nit (candela per square meter). The floating-point luminance values should be multiplied by EGL_METADATA_SCALING, a constant scaling factor of 50000, before being passed into eglSurfaceAttrib as integers. Exactly how the color volume information is used to assist the color reproduction process is implementation dependant. The initial values of EGL_CTA861_3_MAX_CONTENT_LIGHT_LEVEL_EXT and EGL_CTA861_3_MAX_FRAME_AVERAGE_LEVEL_EXT are EGL_DONT_CARE, which causes the hints to be ignored. If value is not in the implementation's supported range for attribute, a EGL_INVALID_VALUE error is generated, and some or all of the metadata fields are ignored. Change the original footnote 12 at the end of section "3.5.6 Surface Attributes" on page 45 to, [13] EGL_DISPLAY_SCALING (10000) and EGL_METADATA_SCALING_EXT (50000) are used where EGL needs to take or return floating-point attribute values, which would normally be smaller than 1, as integers while still retaining sufficient precision to be meaningful. Addition to Table 3.5 "Queryable surface attributes and types", Attribute Type ------------------------------------------------ EGL_CTA861_3_MAX_CONTENT_LIGHT_LEVEL_EXT integer EGL_CTA861_3_MAX_FRAME_AVERAGE_LEVEL_EXT integer Description -------------------------------------------------------------------------------------- Maximum content light level in nit multiplied by EGL_METADATA_SCALING_EXT Maximum frame average light level in nit multiplied by EGL_METADATA_SCALING_EXT Add the following paragraph at the end of section "3.5.6 Surface Attributes" on page 45, Querying EGL_CTA861_3_MAX_CONTENT_LIGHT_LEVEL_EXT EGL_CTA861_3_MAX_- FRAME_AVERAGE_LEVEL_EXT returns respectively the maximum content light level and maximum frame average level respectively. The values returned are in units of 1 nit (candela per square meter), multiplied by the constant value EGL_METADATA_SCALING_EXT (50000). The value of EGL_CTA861_3_MAX_- CONTENT_LIGHT_LEVEL_EXT and EGL_CTA861_3_MAX_FRAME_AVERAGE_LEVEL_EXT can be set via eglSurfaceAttrib as described above. Errors Described in the body text above. Issues Revision History Version 1, 2017/02/28 - Initial draft