1/*
2 * Copyright 2010, Google Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 *     * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *     * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 *     * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32/*
33 * This is an optimized version of the YUV to RGB conversion shader.  This
34 * shader assumes the height of U and V planes is odd, which means the height
35 * of the original image is 2 modulo 4.
36 */
37
38uniform sampler2D textureSampler;
39uniform sampler2D paritySampler;
40
41varying vec2 lineCounter;
42varying vec2 yPlane;
43varying vec2 uPlane;
44varying vec2 vPlane;
45
46#if defined (USE_UNIFORM_MATRIX)
47uniform mat4 conversion;
48#endif
49
50void main() {
51  /*
52   * If the height of the original image is even, offset_odd is not needed.
53   */
54  vec2 offset_even = vec2(texture2D(paritySampler, lineCounter).x * 0.5, 0.0);
55  vec2 offset_odd = vec2(0.5 - offset_even.x, 0.0);
56
57  float yChannel = texture2D(textureSampler, yPlane).x;
58  float uChannel = texture2D(textureSampler, uPlane + offset_even).x;
59  float vChannel = texture2D(textureSampler, vPlane + offset_odd).x;
60
61  /*
62   * This does the colorspace conversion from Y'UV to RGB as a matrix
63   * multiply.  It also does the offset of the U and V channels from
64   * [0,1] to [-.5,.5] as part of the transform.
65   */
66  vec4 channels = vec4(yChannel, uChannel, vChannel, 1.0);
67#if !defined(USE_UNIFORM_MATRIX)
68  mat4 conversion = mat4( 1.0,    1.0,    1.0,   0.0,
69                          0.0,   -0.344,  1.772, 0.0,
70                          1.402, -0.714,  0.0,   0.0,
71                         -0.701,  0.529, -0.886, 1.0);
72#endif
73
74  gl_FragColor = conversion * channels;
75}
76