Initial Commit

rcbasic_runtime/theoraplay_cvtrgb.h

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+/**
+ * TheoraPlay; multithreaded Ogg Theora/Ogg Vorbis decoding.
+ *
+ * Please see the file LICENSE.txt in the source's root directory.
+ *
+ *  This file written by Ryan C. Gordon.
+ */
+
+#if !THEORAPLAY_INTERNAL
+#error Do not include this in your app. It is used internally by TheoraPlay.
+#endif
+
+static unsigned char *THEORAPLAY_CVT_FNNAME_420(const th_info *tinfo,
+                                                const th_ycbcr_buffer ycbcr)
+{
+    const int w = tinfo->pic_width;
+    const int h = tinfo->pic_height;
+    unsigned char *pixels = (unsigned char *) malloc(w * h * 4);
+    if (pixels)
+    {
+        unsigned char *dst = pixels;
+        const int ystride = ycbcr[0].stride;
+        const int cbstride = ycbcr[1].stride;
+        const int crstride = ycbcr[2].stride;
+        const int yoff = (tinfo->pic_x & ~1) + ystride * (tinfo->pic_y & ~1);
+        const int cboff = (tinfo->pic_x / 2) + (cbstride) * (tinfo->pic_y / 2);
+        const unsigned char *py = ycbcr[0].data + yoff;
+        const unsigned char *pcb = ycbcr[1].data + cboff;
+        const unsigned char *pcr = ycbcr[2].data + cboff;
+        int posx, posy;
+
+        for (posy = 0; posy < h; posy++)
+        {
+            for (posx = 0; posx < w; posx++)
+            {
+                // http://www.theora.org/doc/Theora.pdf, 1.1 spec,
+                //  chapter 4.2 (Y'CbCr -> Y'PbPr -> R'G'B')
+                // These constants apparently work for NTSC _and_ PAL/SECAM.
+                const float yoffset = 16.0f;
+                const float yexcursion = 219.0f;
+                const float cboffset = 128.0f;
+                const float cbexcursion = 224.0f;
+                const float croffset = 128.0f;
+                const float crexcursion = 224.0f;
+                const float kr = 0.299f;
+                const float kb = 0.114f;
+
+                const float y = (((float) py[posx]) - yoffset) / yexcursion;
+                const float pb = (((float) pcb[posx / 2]) - cboffset) / cbexcursion;
+                const float pr = (((float) pcr[posx / 2]) - croffset) / crexcursion;
+                const float r = (y + (2.0f * (1.0f - kr) * pr)) * 255.0f;
+                const float g = (y - ((2.0f * (((1.0f - kb) * kb) / ((1.0f - kb) - kr))) * pb) - ((2.0f * (((1.0f - kr) * kr) / ((1.0f - kb) - kr))) * pr)) * 255.0f;
+                const float b = (y + (2.0f * (1.0f - kb) * pb)) * 255.0f;
+
+                *(dst++) = (unsigned char) ((r < 0.0f) ? 0.0f : (r > 255.0f) ? 255.0f : r);
+                *(dst++) = (unsigned char) ((g < 0.0f) ? 0.0f : (g > 255.0f) ? 255.0f : g);
+                *(dst++) = (unsigned char) ((b < 0.0f) ? 0.0f : (b > 255.0f) ? 255.0f : b);
+                #if THEORAPLAY_CVT_RGB_ALPHA
+                *(dst++) = 0xFF;
+                #endif
+            } // for
+
+            // adjust to the start of the next line.
+            py += ystride;
+            pcb += cbstride * (posy % 2);
+            pcr += crstride * (posy % 2);
+        } // for
+    } // if
+
+    return pixels;
+} // THEORAPLAY_CVT_FNNAME_420
+
+// end of theoraplay_cvtrgb.h ...
+