yuv-to-rgb.c

yuv-to-rgb.c

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+/*
+ * Copyright 2018 Google LLC. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+/*
+ *  Brute force conversion from YUV->RGB for testing only. Replace with WebGL
+ *  shader conversion ASAP.
+ *  NOTE: This code explicitly knows that the input is 16-bit 4:2:0 YCbCr
+ *  and assumes there's space for 8-bit/channel RGB to write into.
+ *  NO ERROR CHECKING!
+ */
+#include <stdlib.h>
+#include <stdio.h>
+
+#define ZOF_TAB     65536
+#define ZOF_RGB     3
+
+static int      T1[ZOF_TAB], T2[ZOF_TAB], T3[ZOF_TAB], T4[ZOF_TAB];
+static int      initialized;
+
+static void
+build_tables() {
+    int     i;
+
+    for (i = 0;i < ZOF_TAB; i++) {
+        T1[i] = (int)(1.370705 * (float)(i - 128));
+        T2[i] = (int)(-0.698001 * (float)(i - 128));
+        T3[i] = (int)(-0.337633 * (float)(i - 128));
+        T4[i] = (int)(1.732446 * (float)(i - 128));
+    }
+}
+
+#define clamp(val)  ((val) < 0 ? 0 : (255 < (val) ? 255 : (val)))
+static int foo;
+static int frame;
+
+void
+AVX_YUV_to_RGB(unsigned char *dst, unsigned short *src, int width, int height) {
+    int             r, g, b;
+    unsigned short  *y, *u, *v, *uline, *vline;
+    int             w, h;
+
+    if (initialized == 0) {
+        initialized = !0;
+        build_tables();
+    }
+    // Setup pointers to the Y, U, V planes
+    y = src;
+    u = src + (width * height);
+    v = u + (width * height) / 4;   // Each chroma does 4 pixels in 4:2:0
+    // Loop the image, taking into account sub-sample for the chroma channels
+    for (h = 0; h < height; h++) {
+        uline = u;
+        vline = v;
+        for (w = 0; w < width; w++, y++) {
+            r = *y + T1[*vline];
+            g = *y + T2[*vline] + T3[*uline];
+            b = *y + T4[*uline];
+            dst[0] = clamp(r);     // 16-bit to 8-bit, chuck precision
+            dst[1] = clamp(g);
+            dst[2] = clamp(b);
+            dst += ZOF_RGB;
+            if (w & 0x01) {
+                uline++;
+                vline++;
+            }
+        }
+        if (h & 0x01) {
+            u += width / 2;
+            v += width / 2;
+        }
+    }
+}