Initial import of streamer source code

1 files changed, 42 insertions, 0 deletions

diff --git a/chroma.glsl b/chroma.glsl
new file mode 100644
index 0000000..9004793
--- /dev/null
+++ b/chroma.glsl
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2023 Mikhail Burakov. This file is part of streamer.
+ *
+ * streamer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * streamer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with streamer.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+uniform sampler2D img_input;
+uniform mediump vec2 chroma_offsets;
+
+varying mediump vec2 texcoord;
+
+mediump vec2 rgb2chroma(in mediump vec4 rgb) {
+  // mburakov: This hardcodes BT.709 full-range.
+  mediump float y = rgb.r * 0.2126 + rgb.g * 0.7152 + rgb.b * 0.0722;
+  mediump float u = (rgb.b - y) / (2.0 * (1.0 - 0.0722));
+  mediump float v = (rgb.r - y) / (2.0 * (1.0 - 0.2126));
+  return vec2(u + 0.5, v + 0.5);
+}
+
+void main() {
+  mediump vec2 sample_points[4];
+  sample_points[0] = texcoord;
+  sample_points[1] = texcoord + vec2(chroma_offsets.x, 0.0);
+  sample_points[2] = texcoord + vec2(0.0, chroma_offsets.y);
+  sample_points[3] = texcoord + chroma_offsets;
+  mediump vec4 rgb = texture2D(img_input, sample_points[0]) +
+                     texture2D(img_input, sample_points[1]) +
+                     texture2D(img_input, sample_points[2]) +
+                     texture2D(img_input, sample_points[3]);
+  gl_FragColor = vec4(rgb2chroma(rgb / 4.0), 0.0, 1.0);
+}