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+Name
+
+    MESA_ycbcr_texture
+
+Name Strings
+
+    GL_MESA_ycbcr_texture
+
+Contact
+
+    Brian Paul, Tungsten Graphics, Inc. (brian 'at' tungstengraphics.com)
+    Keith Whitwell, Tungsten Graphics, Inc.  (keith 'at' tungstengraphics.com)
+
+Status
+
+    Shipping (Mesa 4.0.4 and later)
+
+Version
+
+    1.0
+
+Number
+
+    TBD
+
+Dependencies
+
+    OpenGL 1.0 or later is required
+    This extensions is written against the OpenGL 1.4 Specification.
+    NV_texture_rectangle effects the definition of this extension.
+
+Overview
+
+    This extension supports texture images in the YCbCr format.  There is
+    no support for converting YCbCr images to RGB or vice versa.  The
+    intention is for YCbCr image data to be directly sent to the renderer
+    without any pixel transfer operations.  Only 2D texture images are
+    supported (not glDrawPixels, glReadPixels, etc).
+
+    A YCbCr pixel (texel) is a 16-bit unsigned short with two components.
+    The first component is luminance (Y).  For pixels in even-numbered
+    image columns, the second component is Cb.  For pixels in odd-numbered
+    image columns, the second component is Cr.  If one were to convert the
+    data to RGB one would need to examine two pixels from columns N and N+1
+    (where N is even) to deduce the RGB color.
+
+IP Status
+
+    None
+
+Issues
+
+    None
+
+New Procedures and Functions
+
+    None
+
+New Tokens
+
+    Accepted by the <internalFormat> and <format> parameters of
+    TexImage2D and TexSubImage2D:
+
+        GL_YCBCR_MESA                   0x8757
+
+    Accepted by the <type> parameter of TexImage2D and TexSubImage2D:
+
+        GL_UNSIGNED_SHORT_8_8_MESA      0x85BA /* same as Apple's */
+        GL_UNSIGNED_SHORT_8_8_REV_MESA  0x85BB /* same as Apple's */
+
+Additions to Chapter 2 of the OpenGL 1.4 Specification (OpenGL Operation)
+
+    None
+
+Additions to Chapter 3 of the OpenGL 1.4 Specification (Rasterization)
+
+    In section 3.6.4, Rasterization of Pixel Rectangles, on page 102,
+    add the following to Table 3.8 (Packed pixel formats):
+    
+    type Parameter                GL Data   Number of        Matching
+     Token Name                    Type     Components     Pixel Formats
+    --------------                -------   ----------     -------------
+    UNSIGNED_SHORT_8_8_MESA       ushort         3         YCBCR_422_MESA
+    UNSIGNED_SHORT_8_8_REV_MESA   ushort         3         YCBCR_422_MESA
+
+
+    In section 3.6.4, Rasterization of Pixel Rectangles, on page 102,
+    add the following to Table 3.10 (UNSIGNED_SHORT formats):
+
+    UNSIGNED_SHORT_8_8_MESA:
+
+      15  14  13  12  11  10  9   8   7   6   5   4   3   2   1   0
+    +-------------------------------+-------------------------------+
+    |              1st              |              2nd              |
+    +-------------------------------+-------------------------------+
+                        
+    UNSIGNED_SHORT_8_8_REV_MESA:
+
+      15  14  13  12  11  10  9   8   7   6   5   4   3   2   1   0
+    +-------------------------------+-------------------------------+
+    |              2nd              |              1st              |
+    +-------------------------------+-------------------------------+
+
+
+    In section 3.6.4, Rasterization of Pixel Rectangles, on page 102,
+    add the following to Table 3.12 (Packed pixel fiedl assignments):
+
+                       First       Second     Third      Fourth
+    Format             Element     Element    Element    Element
+    ------             -------     -------    -------    -------
+    YCBCR_422_MESA     luminance   chroma
+
+
+    In section 3.8.1, Texture Image Specification, on page 125, add
+    another item to the list of TexImage2D and TexImage3D equivalence
+    exceptions:
+
+    * The value of internalformat and format may be YCBCR_MESA to
+      indicate that the image data is in YCbCr format.  type must
+      be either UNSIGNED_SHORT_8_8_MESA or UNSIGNED_SHORT_8_8_REV_MESA
+      as seen in tables 3.8 and 3.10.  Table 3.12 describes the mapping
+      between Y and Cb/Cr to the components.
+      If NV_texture_rectangle is supported target may also be
+      TEXTURE_RECTANGLE_NV or PROXY_TEXTURE_RECTANGLE_NV.
+      All pixel transfer operations are bypassed.  The texture is stored as
+      YCbCr, not RGB.  Queries of the texture's red, green and blue component
+      sizes will return zero.
+
+
+    In section 3.8.1, Texture Image Specification, on page 126, add
+    another item to the list of TexImage1D and TexImage2D equivalence
+    exceptions:
+
+    * The value of internalformat and format can not be YCBCR_MESA.
+
+
+    In section 3.8.2, Alternate Texture Image Specification Commands, on
+    page 129, insert this paragraph after the first full paragraph on the
+    page:
+
+         "If the internal storage format of the image being updated by
+    TexSubImage2D is YCBCR_MESA then format must be YCBCR_MESA.
+    The error INVALID_OPERATION will be generated otherwise."
+
+
+Additions to Chapter 4 of the OpenGL 1.4 Specification (Per-Fragment
+Operations and the Frame Buffer)
+
+    None
+
+Additions to Chapter 5 of the OpenGL 1.4 Specification (Special Functions)
+
+    None
+
+Additions to Chapter 6 of the OpenGL 1.4 Specification (State and
+State Requests)
+
+    None
+
+Additions to Appendix A of the OpenGL 1.4 Specification (Invariance)
+
+    None
+
+Additions to the AGL/GLX/WGL Specifications
+
+    None
+
+GLX Protocol
+
+    None
+
+Errors
+
+    INVALID_ENUM is generated by TexImage2D if <internalFormat> is
+    MESA_YCBCR but <format> is not MESA_YCBCR.
+
+    INVALID_ENUM is generated by TexImage2D if <format> is MESA_YCBCR but
+    <internalFormat> is not MESA_YCBCR.
+
+    INVALID_VALUE is generated by TexImage2D if <format> is MESA_YCBCR and
+    <internalFormat> is MESA_YCBCR and <border> is not zero.
+
+    INVALID_OPERATION is generated by TexSubImage2D if the internal image
+    format is YCBCR_MESA and format is not YCBCR_MESA.
+
+    INVALID_OPERATION is generated by CopyTexSubImage2D if the internal
+    image is YCBCR_MESA.
+    
+New State
+
+    Edit table 6.16 on page 231: change the type of TEXTURE_INTERNAL_FORMAT
+    from n x Z42 to n x Z43 to indicate that internal format may also be
+    YCBCR_MESA.
+
+Revision History
+
+    20 September 2002 - Initial draft