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'''OpenGL extension APPLE.ycbcr_422
This module customises the behaviour of the
OpenGL.raw.GL.APPLE.ycbcr_422 to provide a more
Python-friendly API
Overview (from the spec)
This extension provides a method for GL to read, store and optionally
process textures that are defined in Y'CbCr 422 video formats. This
extension supports the two common Y'CbCr 422 video formats (known by
QuickTime FourCC as '2vuy' and 'yuvs'). These formats represent one of the
most common 16 bit Y'CbCr formats in both standard and reverse byte
ordering. From a client stand point these can be assumed to be decoded
immediately (even though the implementation is free to optimize the data
storage and keep it in the native format) and otherwise function as any
other texture format. The texture command <internalformat> parameter
normally be should be specified as RGB, since Y'CbCr is just a form of RGB
data. This extension can be supported with either hardware or software
decoding and it is up to the specific implementation to determine which is
used.
A new <format> is added, YCBCR_422_APPLE. Additionally, to handle the
difference in pixel size and byte ordering for 422 video, the pixel storage
operations treat YCBCR_422_APPLE as a 2 component format using
the UNSIGNED_SHORT_8_8_APPLE or UNSIGNED_SHORT_8_8_REV_APPLE <type>.
The '2vuy' or k2vuyPixelFormat pixel format is an 8-bit 4:2:2 Component
Y'CbCr format. Each 16 bit pixel is represented by an unsigned eight bit
luminance component and two unsigned eight bit chroma components. Each pair
of pixels shares a common set of chroma values. The components are ordered
in memory; Cb, Y0, Cr, Y1. The luminance components have a range of [16,
235], while the chroma value has a range of [16, 240]. This is consistent
with the CCIR601 spec. This format is fairly prevalent on both Mac and Win32
platforms. The equivalent Microsoft fourCC is OUYVYO. This format is
supported with the UNSIGNED_SHORT_8_8_REV_APPLE type for pixel storage
operations.
The 'yuvs' or kYUVSPixelFormat is an 8-bit 4:2:2 Component Y'CbCr format.
Identical to the k2vuyPixelFormat except each 16 bit word has been byte
swapped. This results in a component ordering of; Y0, Cb, Y1, Cr. This is
most prevalent yuv 4:2:2 format on both Mac and Win32 platforms. The
equivalent Microsoft fourCC is 'YUY2'. This format is supported with the
UNSIGNED_SHORT_8_8_APPLE type for pixel storage operations.
The official definition of this extension is available here:
http://www.opengl.org/registry/specs/APPLE/ycbcr_422.txt
'''
from OpenGL import platform, constants, constant, arrays
from OpenGL import extensions, wrapper
from OpenGL.GL import glget
import ctypes
from OpenGL.raw.GL.APPLE.ycbcr_422 import *
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